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TABLE OF CONTENTS ......................... ERROR! BOOKMARK NOT DEFINED.1

FOREWORD......................................................................................................... 6
  The rice plant ............................................................................................................... 7
  The seed and grain ...................................................................................................... 8
  Parts of a seed ............................................................................................................. 9

REPRODUCTIVE PARTS OF THE RICE PLANT .............................................. 10
  The spikelet ............................................................................................................... 10
  Stages of seed formation ........................................................................................... 11
  Inbred rice seed ......................................................................................................... 12
  Hybrid rice seed ......................................................................................................... 13
  Male sterile line .......................................................................................................... 14
  Maintainer line............................................................................................................ 14
  Restorer line .............................................................................................................. 16
  Desirable characteristics of the CMS line ................................................................... 16
  Desirable characteristics of maintainer and restorer lines .......................................... 17
  Choice of parents for hybrid seed production ............................................................. 18

SEEDING OF PARENTAL LINES IN THE SEEDBED ....................................... 19
  Why seed in the seedbed? ......................................................................................... 19
  Seedbed preparation.................................................................................................. 19
  Pregerminating seeds ................................................................................................ 20
  Managing the seedbed............................................................................................... 21

SYNCHRONIZATION OF FLOWERING ............................................................ 21
  Differential seeding .................................................................................................... 21
  How to determine seeding time of A and R lines ........................................................ 22

DIFFERENTIAL SEEDING TIMES ..................................................................... 23
  Seed parent has 10-day shorter growth duration than pollen parent .......................... 23
  Seed parent has 10-day longer growth duration than pollen parent............................ 23
  Seed parent has same growth duration as pollen parent ............................................ 24
  Differential seeding times for CMS multiplication ........................................................ 26

SELECTION OF CMS MULTIPLICATION AND HYBRID SEED PRODUCTION
FIELDS ............................................................................................................... 26
  Requirements............................................................................................................. 26



                                                                                                                                2
  Distance isolation ....................................................................................................... 27
  Time isolation ............................................................................................................. 27
  Barrier isolation .......................................................................................................... 28

TRANSPLANTING ............................................................................................. 28
  Why transplant? ......................................................................................................... 28
  How to transplant ....................................................................................................... 28
  How many seedlings per hill? ..................................................................................... 29
  Layout for transplanting .............................................................................................. 29
  Seedling age at transplanting ..................................................................................... 29

TRANSPLANTING IN A SPECIFIC ROW RATIO .............................................. 30
     What is a row ratio? .................................................................................................................30
     Factors influencing row ratio ...................................................................................................30
     Flowering behavior of the A and R lines .................................................................................31
  Transplanting Sequence for CMS Multiplication ......................................................... 31
     Transplanting A and B line ......................................................................................................31

TRANSPLANTING SEQUENCE FOR HYBRID SEED PRODUCTION ............. 33
        Seed parent has 10-day shorter growth duration than pollen parent - Transplanting the A and R line33
        Seed parent has 10-day longer growth duration than pollen parent - Transplanting the A and R line 34
        Seed parent has same growth duration as pollen parent - Transplanting the A and R line ................ 35
     Change the seedling proportion of R line ................................................................................36
     Seed the R line twice ...............................................................................................................38
     Modify row ratios .....................................................................................................................39
     Modify row and plant spacings ................................................................................................39

MANAGEMENT OF SEED PRODUCTION PLOTS ........................................... 40
  Retransplant missing hills .......................................................................................... 40
  Control weeds ............................................................................................................ 40
  Control diseases and insect-pests.............................................................................. 41
  Fertilizer management ............................................................................................... 42

ADJUSTING FLOWERING DATE...................................................................... 43
  Synchronization of flowering date of parental lines ..................................................... 43
  Panicle initiation and flowering date ........................................................................... 43
  How to observe panicle initiation ................................................................................ 43
  Development stages of panicle formation to flowering ................................................ 44
  Estimating flowering date by panicle primordium stage .............................................. 45
  How to adjust flowering date of parental lines showing 5-6 days difference ............... 46



                                                                                                                                            3
  How to adjust flowering date of parental lines showing a difference of more than a
  week .......................................................................................................................... 46

FLAG LEAF CUTTING ....................................................................................... 47
  Crop stage for flag leaf clipping .................................................................................. 47
  Flag leaf clipping method ........................................................................................... 47

GIBBERELLIC ACID APPLICATION ................................................................. 48
  Why spray gibberellic acid?........................................................................................ 48
  Timing of application-crop growth stage ..................................................................... 48
  Timing of application-weather conditions.................................................................... 49
  How to make GA3 solution general procedure ........................................................... 50
  How to make GA3 solution amount required for different size plots ............................ 50
  How to make GA3 solution doing your own computations .......................................... 52

SUPPLEMENTARY POLLINATION ................................................................... 52
  Methods of supplementary pollination ........................................................................ 52
  Timing of supplementary pollination ........................................................................... 53

ROGUING ........................................................................................................... 53
  What is roguing and why is it necessary? ................................................................... 53
  Crop stage for roguing ............................................................................................... 53
  Off types to be removed ............................................................................................. 54
  At flowering and before harvest .................................................................................. 54

HARVESTING .................................................................................................... 55
  Special considerations for harvesting hybrid rice ........................................................ 55
  When to harvest ......................................................................................................... 55
  Harvesting the B or R line .......................................................................................... 55
  Harvesting the A line .................................................................................................. 56

THRESHING ....................................................................................................... 57
  Preparation for threshing ............................................................................................ 57
  Threshing the seed and pollen parent ........................................................................ 58

SEED DRYING ................................................................................................... 58
  Why seed drying? ...................................................................................................... 58
  Seed drying methods-sun drying ................................................................................ 59
  Seed drying methods-forced air drying ....................................................................... 59



                                                                                                                                  4
PROCESSING HYBRID RICE SEED FOR MARKET ........................................ 59
  Cleaning and grading ................................................................................................. 59
  Seed germination testing ........................................................................................... 60
  Packing and labeling the seed ................................................................................... 61

CITATION ........................................................................................................... 62

INDEX ................................................................................................................. 63




                                                                                                                         5
Foreword
Hybrid rice technology exploits the phenomenon of hybrid vigor and involves raising a commercial
crop F1 seeds. This technology helped China to increase its rice production from 140 million tons
in 1978 to 188 million tons in 1990.

Research at IRRI and in other countries indicates that hybrid rice technology offers opportunities
for increasing rice varietal yields by 15-20% beyond those achievable with improved, semidwarf,
inbred varieties.

Adoption and success of hybrid rice technology will depend largely on practical seed production
technology; economical seed yields from hybrid rice plots; and efficient national seed production,
processing, certification, and distribution programs in public and private sector.

Hybrid rice seed production technology involves specialized skills and requires a thorough
understanding of various practices to minimize costs and maximize returns. This manual
describes and illustrates the many steps involved in hybrid rice seed production for both
beginning and experienced seed growers. It is based on experiments at IRRI and hybrid rice seed
production experience in China. The authors have presented a complex topic in systematic, easy-
to-understand terms that should appeal to trainers and growers alike. This manual was edited by
W.H. Smith with the assistance of T. Rola.

Intially, the manual was designed for easy translation and inexpensive copublication in
nonindustrialized countries. IRRI will give complimentary sets of the illustrations to cooperators
who wish to translate the text and print local-language editions of the manual.




                                                                                                     6
The rice plant
     A tiller is a shoot that includes the roots, stem, and leaves. It may or may not have a
      panicle.
     The panicle bears the spikelets.
     The spikelets are the parts of the rice plant that form seed.




                                                                                                7
The seed and grain
    A mature rice grain that germinates under favorable environmental conditions and grows
     into a normal plant is called a seed.
    A mature rice grain that may or may not germinate and is used for consumption is not a
     seed.
    Only seed can be sold to farmers to grow a rice crop.




                                                                                          8
Parts of a seed
     The embryo or germ gives rise to a seedling, which is composed of the shoot and the
      roots. The endosperm is a food reserve for the germinating embryo during its early
      growth. The endosperm is made up mostly of starch. It also contains sugars, proteins,
      and fats.
     The hull is the hard cover of the seed.
     Most improved rice cultivars either do not have awns, or the awn is very small.




                                                                                              9
Reproductive Parts of the Rice Plant
The spikelet
     The stamens are the male reproductive organs. Each stamen is made up of an anther,
      which contains pollen grains, and the filament.
     The pistil is the female reproductive organ. It is made up of the ovary, a short style, and
      two feathery stigmas.




                                                                                                    10
     Pollination is the first step in reproduction. Pollen grains are shed from the anthers and
      fall onto the feathery stigmas.
     Fertilization is the second step in seed formation. The pollen that reaches the stigma
      germinates and forms a pollen tube that carries the male nuclei inside the ovary for fusion
      with the egg nuclei.
     The complete process from pollination to fertilization takes from 18 to 24 hours.




Stages of seed formation
     The fertilized egg cell begins development within 12 hours after fertilization.
     The endosperm of the developing seed begins turning milky white 8 days after
      fertilization. The embryo develops after 10 days.
     The endosperm turns into the soft dough stage at 14 days after fertilization, and the hard
      dough stage 7 days later.
     Within 25-30 days after fertilization, the ovule has matured and fully ripened into a seed.




                                                                                               11
Inbred rice seed
     Ordinary or inbred rice seed is produced when the egg inside the ovary is fertilized by
      pollen grains shed from:
      o anthers borne in the same spikelet.
      o anthers from other spikelets of the same plant.
      o anthers from the spikelet of another plant of the same variety.
     When farmers plant an entire field to a single variety, they are producing inbred seed.




                                                                                                12
Hybrid rice seed
     Hybrid rice seed is produced when the egg is fertilized by pollen from the anthers of a
      rice plant from a different variety or line.
     Hybrid rice seed is the first filial (F1) generation of a cross of two rice varieties that are
      genetically different.




                                                                                                       13
Male sterile line
     A rice line that cannot produce viable pollen due to the interaction between cytoplasmic
      and nuclear genes is described as being cytoplasmic male sterile (CMS).
     It is used as a female parent for hybrid rice seed production.
     The male sterile line is commonly called a CMS line, the seed parent, the female parent,
      or the A line.
     Panicles may not exsert fully. Their basal portion remains inside the flag leaf sheath.
     Anthers are pale or white and shrivelled.
     The flowering period usually lasts for 7 days.




Maintainer line
     A maintainer line is similar to a CMS line except that it has viable pollen grains and
      normal seed setting.
     The maintainer line is used as a pollinator for maintaining a CMS line.
     The maintainer is also called the B line.
     The B line cannot restore fertility to the F1 generation when it is crossed with a CMS line.
     Panicles exsert fully out of the flag leaves.
     Anthers are yellow, plump, and shed pollen.
     The B line flowers 2-3 days earlier than the CMS line.



                                                                                                14
   Flowering lasts for about 5 days.




                                        15
Restorer line
     Any rice cultivar that restores fertility in the F1 when it is crossed to a CMS line is called a
      restorer.
     The restorer is also called the pollen parent, the male parent, or the R line.
     The R line is used as the pollinator for the CMS parent for hybrid seed production.
     Growth duration may or may not be similar to that of CMS lines.
     Panicles exsert fully out of the flag leaves.
     Anthers are yellow, plump, and shed pollen.
     Flowering lasts for about 5 days.




Desirable characteristics of the CMS line
     High seed yields depend on desirable panicle, floret, and stigma characteristics of the
      CMS line.
     The panicle should be exserted from the flag leaf as far as possible.
     There should be at least 100 spikelets per panicle.
     The floret should open wide and remain open for at least 45 minutes or longer.
     Blooming florets should have exserted stigmas.
     Stigmas should be receptive to pollination for 5 to 7 days.




                                                                                                   16
Desirable characteristics of maintainer and
restorer lines
     Panicles should be:
      o long and contain 125 or more spikelets.
      o completely exserted from the flag leaf.
     Filaments should be long for complete anther exertion from the floret.
     Anthers should be large and plump with many pollen grains.
     The anther should shed most of its pollen only after it has exerted from the floret.




                                                                                             17
Choice of parents for hybrid seed production
     Seed growers normally produce seeds of F1 hybrids released for commercial cultivation
      in their country.
     The parental lines should be adapted to the grower's area, even if the hybrid seed may
      be produced for another geographical area.
     Government agencies or commercial seed companies are the grower's best source of
      parental seed of hybrids that are popular with farmers.




                                                                                           18
Seeding of Parental Lines in the Seedbed
Why seed in the seedbed?
     Seeding in the seedbed ensures proper germination of the parental seed material.
     The seedbed provides healthy and vigorous seedlings for transplanting.




Seedbed preparation
     Puddle the seedbed field twice at an interval of 7 days to destroy any germinated rice
      seeds or weed seeds.
     Construct 5-10-cm raised seedbeds of approximately 1 m width of any convenient length.
     Construct drainage channels between seedbeds to drain excess water.
     Apply 5-6 grams of NPK (14:14:14) fertilizer or ammonium phosphate (16:20) fertilizer for
      each square meter of seedbed area and mix it with the soil.
     Nitrogen increases seedling growth and induces tillering.




                                                                                            19
Pregerminating seeds
    Soak the seeds in water for 24 hours.
    Stir the seeds upon soaking and discard those that float on the surface.
    Incubate the seeds for 24 hours in a warm and shady place.
    Seeds can be incubated in moist jute sacks.
    Allow room in the sacks for expansion of the seeds during incubation.
    Incubation keeps the seeds warm, increases growth of the embryo, and results in uniform
     germination.
    Sow pregerminated seeds uniformly on the seedbed at the rate of 1 kg seed per 20 m2 of
     seedbed.
    To produce enough seedlings to grow 1 hectare of hybrid rice, you need 15 kg of A line
     seed and 5 kg of R line seed.




                                                                                         20
Managing the seedbed
       Irrigate the seedbed to a depth of 2-3 cm.
       Drain off the water occasionally to attain vigorous seedlings.
       Gradually increase water depth to 5 cm to control weeds.
       Pull remaining weeds by hand; weeds compete with seedlings for light, water, and
        nutrients.




Synchronization of Flowering
Differential seeding
Success in CMS line multiplication or growing hybrid seed depends on synchronizing the
flowering of the seed parent and the pollen parent. By synchronizing flowering, we mean that the
seed and the pollinator parents flower at the same time in the field, even though they may have
different growth durations. Synchronizing flowering is important because we want pollen from the
B or R line to be available to the A line throughout its flowering period.

Synchronization of flowering can be done in two ways:

    1. We can adjust the seeding dates of the parents in the seedbed so they flower at the
       same time in the field. That is called differential seeding. Seeding time always depends
       on the growth duration of the parents, whether you are multiplying a CMS line or
       producing hybrid seed.

    2. We can adjust the flowering date in the field by crop management practices later in the
       growing season. These are explained in the section on entitled Adjusting flowering date.




                                                                                                  21
How to determine seeding time of A and R lines
       In hybrid seed production, we normally seed the R line three times. The seeding dates
        are separated by 3-day intervals.
       The A line is always seeded just once.
       The seeding of the A line and the second seeding of the R line are separated by the
        number of days difference in their growth duration.

If the A line growth duration is shorter, the second R line seeding is done before the A line.
Example 1:
R line growth duration = 100 days                 A line growth duration = 90 days
The A line has a 10-day shorter growth duration; therefore the second seeding of the R line will
be 10 days before the A line.
If the A line growth duration is longer, the second R line seeding is done after the A line.

Example 2:
R line growth duration = 90 days                    A line growth duration = 100 days
The A line has a 10-day longer growth duration; therefore the second seeding of the R line will be
10 days after the A line.
      If both parental lines have the same growth duration, the A line seeding and the second
         R line seeding would be done on the same day.
      We do the first seeding of the R line 6 days earlier than the second seeding. We do the
         third seeding of the R line 6 days later than the second seeding.




                                                                                                22
Differential Seeding Times
Seed parent has 10-day shorter growth duration
than pollen parent
Number of seedings:
A line--one R line--three

      Begin the seeding sequence by seeding the R line on the first day.
      Do the second seeding of the R line 6 days after the first seeding.
      Do the third seeding of the R line 6 days after the second seeding.
      Seed the A line 4 days after the third seeding of the R line.
      The three seedings of the R line will supply pollen for a prolonged duration during the
       flowering period of the A line.




Seed parent has 10-day longer growth duration
than pollen parent
Number of seedings:
A line--one R line--three

      Begin the seeding sequence by seeding the A line on the first day.
      Do the first seeding of the R line 4 days after the seeding of the A line.
      Do the second seeding of the R line 6 days after the first seeding.


                                                                                                 23
      Do the third seeding of the R line 6 days after the second seeding.
      The three seedings of the R line will supply pollen for a prolonged duration during the
       flowering period of the A line.




Seed parent has same growth duration as pollen
parent
Number of seedings:
A line--one R line-- three

      Begin the seeding sequence by seeding the R line on the first day.
      Do the second seeding of the R line 6 days after the first seeding of the R line.
      Seed the A line on the same day as the second seeding of the R line.
      Do the third seeding of the R line 6 days after the second seeding.
      The three seedings of the R line will supply pollen for a prolonged duration during the
       flowering period of the A line.




                                                                                                 24
25
Differential seeding times for CMS multiplication
Number of seedings:
A line--one B line-- two

       Do differential seeding of A and B lines to synchronize flowering.
       Begin the seeding sequence by seeding the A line on the first day.
       Do the first seeding of the B line 3 days after seeding of the A line.
       Do the second seeding of the B line 3 days after the first seeding of the B line.
       The two seedings of the B line will supply pollen for a prolonged duration during the
        flowering period of the A line.




Selection of CMS Multiplication and Hybrid Seed
Production Fields
Requirements
To grow any rice crop, the requirements for sunlight, soil fertility, and water remain the same. All
rice crops require:
         o fertile soil.
         o adequate irrigation water and drainage.
         o sufficient sunlight for high seed yield.
         o management of insects and soil-borne diseases.
      Fields for CMS line multiplication or hybrid seed production have one more important
         requirement. Seed production plots must be well separated, or isolated, from other
         ricefields to ensure genetic purity of the seed.
      What we mean by protecting genetic purity is that the seed parent (or A line) is only
         pollinated by the male parent chosen as the B line or the R line.
      Pollen from different rice cultivars near seed production plots can contaminate the seed
         parent and lower the quality of the hybrid seed.



                                                                                                   26
     Seed production crops can be isolated from other rice crops by:
      o distance from other ricefields.
      o differences in time of flowering.
      o natural or artificial barriers.

Distance isolation
     Rice pollen grains are small, light, and can be carried distances of up to 100 meters in
      air, within their life span of 3-5 minutes.
     No other rice crop should be grown within 100 m of hybrid seed production plots.
     The isolation distance can be decreased to 50 m, if at least 10 border rows of the pollen
      parent surround the seed production plot.




Time isolation
     Adjust planting time to separate flowering time of the seed parent from other rice cultivars
      within 100 m by at least 3 weeks. That will protect the seed parent from contamination.
     If the seed parent and a nearby cultivar have the same heading date, then the 100-m
      separation distance must be maintained.




                                                                                               27
Barrier isolation
     Any natural, artificial, or crop barrier over 2.5 m high can prevent contamination of the
      seed parent by pollen grains from rice cultivars within 100 m.
     The crop barrier around the seed production plots should be 3-4 m wide, depending upon
      the type of crop.
     Sesbania rostrata or a healthy, tall crop of maize, sorghum, or pearl millet makes a
      satisfactory barrier.




Transplanting
Why transplant?
     Transplanting gives proper plant spacing, resulting in uniform growth.
     Transplanting gives the optimum crop stand for getting maximum seed yield.
     Transplanting makes field operations such as weeding, spraying, fertilizing, and roguing
      easier.
     Hybrid rice is planted in rows in only one direction; plants within rows do not line up
      across rows.




How to transplant
     Seedlings should be transplanted straight upright for early establishment.
     Seedlings should be transplanted 2-3 cm deep in the soil for early plant recovery and
      better tillering.




                                                                                              28
How many seedlings per hill?
       There is no difference in seed yield between one and two seedlings per hill, unless the
        seedling planted alone dies.
       Transplant one or two seedlings per hill of the A line.
       Transplant two seedlings per hill of B or R lines. The seed is plentiful and if one seedling
        dies, the remaining seedling can produce sufficient tillers.




Layout for transplanting
The rows in the seed production plot should be perpendicular to the prevailing wind direction
expected at flowering time of the parents.

Seedling age at transplanting
       Transplanting 21-day-old seedlings ensures timely heading and flowering of parental
        lines.
       Transplanting older seedlings delays flowering by about half the number of days by which
        the seedlings are older than 21 days.
       Transplanting younger seedlings advances flowering by approximately half the number of
        days by which the seedlings are younger than 21 days.



                                                                                                  29
       If transplanting of seedlings of the A line is delayed, then delay transplanting the B or R
        line seedlings by the same number of days to synchronize flowering.



Transplanting in a Specific Row Ratio
What is a row ratio?
       Row proportion or row ratio refers to the number of rows of the male parent (B or R line)
        to that of the female parent (A line) in a seed production plot.
       For example, if we plant 2 row the B or R line for every 8 rows of A line, we say we have
        a row ratio of 2:8
       The row ratio of the pollen parent to seed parent will vary from region to region,
        depending on weather, management, and parental lines. R and A lines can be planted in
        several row ratios 2:8, 2:12, 3:10, etc
       In this manual, we take an R:A line ratio of 2:8 as normal and use it in most examples.




Factors influencing row ratio
The ratio of pollen parent (R line) to seed parent (A line) is determined by the characteristics of
the parental lines.

Characteristics of the R line
There can be more than 8 A line rows in relation to the 2 rows of the pollen parent if R line plants:

       are taller than the seed parent.
       have good growth and vigor.
       have large panicles.
       shed a large amount of residual pollen (the pollen left in the anther at the time of spikelet
        opening).

Characteristics of the A line
There can be more than 8 A line rows in relation to the 2 rows of pollen parent if the A line:


                                                                                                      30
      is shorter than the pollen parent.
      has a long duration of floret opening and stigma receptivity.
      has a wide angle of floret opening.
      has a high percentage of stigma exertion.

Flowering behavior of the A and R lines
      The A and R lines should flower at the same time.
      The A and R lines should be in full bloom at the same time of day during the flowering
       period.
      Pollination increases if both the A and R lines have the maximum number of blooming
       spikelets per unit area per day. That assures that the maximum amount of pollen is
       available when the maximum number of stigma are receptive to pollination.




Transplanting Sequence for CMS Multiplication

Transplanting A and B line
Transplanting the A line
Number of transplantings: A line--one   B line--two
Seedling age: 21 days
Row ratio: 2:6

      On the first day of the transplanting sequence, transplant the A line seedlings in blocks of
       6 rows.
      Space rows 15 cm apart with 15 cm between seedlings within rows.
      Leave a 75-cm wide block between blocks of A line seedlings for transplanting seedlings
       of the B line.




                                                                                                 31
Transplanting the B line
    Transplant seedlings from first B line seeding in paired rows on the 4th day of the
       transplanting sequence.
    Space rows 15 cm apart with 30 cm between seedlings within rows.
    Leave a 30-cm wide alleyway between the B line rows and the nearest A line rows.
    Transplant seedlings of the second B line seeding according to the transplanting
       sequence chart.
    Fill in the vacant spaces in the rows so that plant spacing is 15 cm within rows after the
       second B line seedlings have been transplanted.




                                                                                                  32
Transplanting Sequence for Hybrid Seed
Production
Seed parent has 10-day shorter growth duration
than pollen parent - Transplanting the A and R
line
Number of transplantings: A line-one R line-one
Seedling age: 21 days for A line   15, 21and 27 days for R line
Row ratio: 2:8

Transplanting the R line
    R line seedlings are transplanted when the seedlings from the second R line seeding are
       21 days old. That means that the seedlings from the first seeding will be 27 days old. The
       seedlings from the third seeding will be 15 days old.
    Transplant R line seedlings according to the pattern shown in the drawing.
    Transplant seedlings from first R line seeding in paired rows.
    Space rows 15 cm apart with 45 cm between seedlings within rows.
    Leave a 165-cm wide block between paired rows of R line seedlings for transplanting 8-
       row blocks of A line seedlings.
    Transplant seedlings of the second and third R line seedings on the same day.
    Fill in the vacant spaces in the paired rows so that plant spacing is 15 cm within rows
       after the seedlings of the third R line seeding have been transplanted.

Transplanting the A line
    The A line seedlings are transplanted to synchronize flowering with the second R line
       seeding.
    Transplant the A line seedlings in blocks of 8 rows on the eleventh day of the
       transplanting sequence.
    Space rows 15 cm apart with 15 cm between seedlings within rows.
       o Leave a 30-cm wide alleyway between the A line rows and the nearest R line rows.




                                                                                               33
Seed parent has 10-day longer growth duration
than pollen parent - Transplanting the A and R
line
Number of transplantings: A line-- one R line--one
Seedling age: 21 days for A line 15, 21and 27 days for R line
Row ratio: 2:8

Transplanting the A line
    On the first day of the transplanting sequence, transplant the A line seedlings in blocks of
       8 rows.
    Space rows 15 cm apart with 15 cm between seedlings within rows.
    Leave a 75-cm wide block between blocks of A line seedlings for transplanting the
       seedlings of the R line.

Transplanting the R line
    The R line seedlings are transplanted to synchronize the flowering of the second R line
       seeding with the A line.
    R line seedlings are transplanted when the seedlings from the second R line seeding are
       21 days old. That means that the seedlings from the first seeding will be 26 days old. The
       seedlings from the third seeding will be 16 days old.
    Transplant seedlings of the R line in paired rows on the eleventh day of the transplanting
       sequence.
    Transplant R line seedlings according to the pattern shown in the drawing.
    Space rows 15 cm apart with 45 cm between seedlings within rows.
    Leave a 30-cm wide alleyway between the R line rows and the nearest A line rows


                                                                                               34
       Transplant seedlings of the second and third R line seedings on the same day.
       Fill in the vacant spaces in the paired rows so that plant spacing is 15 cm within rows
        after seedling of the third R line seeding have been transplanted.




Seed parent has same growth duration as pollen
parent - Transplanting the A and R line
Number of transplanting: A line-- one R line-- three
Seedling age: 21 days for A line 15, 21and 27 days for R line
Row ratio: 2:8

Transplanting the R line
    R line seedlings are transplanted when the seedlings from the second R line seeding are
       21 days old. That means that the seedlings from the first seeding will be 27 days old. The
       seedlings from the third seeding will be 15 days old.
    Transplant R line seedlings according to the pattern shown in the drawing.
    Transplant seedlings from first R line seeding in paired rows.
    Space rows 15 cm apart with 45 cm between seedlings within rows.
    Leave a 165-cm wide block between paired rows of R line seedlings for transplanting 8-
       row blocks of A line.
    Transplant seedlings of the second and third R line seedings on the same day.
    Fill in the vacant spaces in the paired rows so that plant spacing is 15 cm within rows
       after seedlings of the third R line seeding have been transplanted.




                                                                                                  35
Transplanting the A line
    Transplant the A line seedlings in blocks of 8 rows on the same day after completing the
       transplanting of the R line seedlings.
    Space rows 15 cm apart with 15 cm between seedlings within rows.
    Leave a 30-cm wide alleyway between the A line rows and the nearest R line rows.

NOTE: The seedlings of the R line and the A line are planted on the same day in the sequence.
Be especially careful not to mix seedlings of the two lines during transplanting.




Change the seedling proportion of R line
      Experienced growers can change seeding and transplanting patterns to increase hybrid
       seed yield.
      Apprentice growers plant an equal number of seedlings from each of the three seedings
       of the R line.
      Experienced growers can double the number of seedlings of the second seeding R line.
      Doubling the number of transplanted seedlings of the second seeding increases the
       amount of residual pollen that will be available to the seed parent at peak flowering.
      The seedbed for the second seeding of the R line should be twice as large as the
       seedbeds for the first and third seedings.
      Transplant seedlings when they are 21 d old.
      The figure shows the transplanting pattern when the seed parent has 10 days longer
       growth duration than the pollen parent.




                                                                                            36
37
Seed the R line twice
     Seed the R line twice instead of three times.
     Adjust the size of your seedbeds so that the number of seedlings from the first seeding is
      twice that of the second seeding.
     The first seeding of the R line should be timed to synchronize flowering with the A line.
      The second seeding of the R line is done 3 days after the first seeding of the R line.
     Transplant seedlings when they are 21 days old. The drawing shows the transplanting
      pattern used when the seed parent has a 10-day shorter growth duration than the pollen
      parent.




                                                                                              38
Modify row ratios
     Experienced growers can change the row ratio of R lines to A lines. Instead of a row ratio
      of 2:8, a ratio of 3:10, 2:10, 2:11, or 2:12 can be used.
     When the grower has perfected the technique of synchronizing the flowering of the R and
      A line, a row ratio of 1:8, 1:9, or 1:10 may be used.




Modify row and plant spacings
     Row and plant spacing can be modified from the recommended 15- ¥ 15-cm spacing,
      depending on local conditions.
     When row and plant spacings are increased, the ratio of A line panicles to R line panicles
      should remain the same.
     The number of productive tillers per hectare should not be less than 3 million for the A
      line or 1 million for the R line. A productive tiller is a tiller that produces a panicle.
     There should be a ratio of 3-3.5 A line panicles to 1 R line panicle.



                                                                                              39
Management of Seed Production Plots
Retransplant missing hills
     Keep the field saturated until the plants recover in 4 or 5 days. Then increase the water
      level to 5 cm.
     Replant all the missing hills within 7 days of transplanting.
     Be careful not to mix A and R seedlings when you replant missing hills.




Control weeds
     Keep the weeds under complete control.
     Weeds can be controlled by:
      o hand pulling.
      o mechanical means such as weeders.
      o herbicides.




                                                                                                  40
Control diseases and insect-pests
     Keep diseases and insect pests under complete control.
     Follow insect and disease control practices recommended for your area.
     Because hybrid seed production is expensive, it is necessary to completely control insect
      pests and diseases to obtain maximum seed yield.




                                                                                             41
Fertilizer management
Fertilizer management
     Apply fertilizers at rates recommended for lowland irrigated conventional rice cultivars in
         your area.
     You should not use a blended fertilizer, such as NPK, on hybrid seed production plots
         because nitrogen (N) fertilizer will be applied separately from phosphorus (P) and
         potassium (K).
     Apply the entire amounts of recommended P and K to the seed production plots just
         before the last puddling.
     Nitrogen should be applied to each parent in three splits. The normal application
         schedule is one-third 5-7 days after transplanting, one- third 20-25 days after the first
         application, and the final one-third at maximum tillering.
     In hybrid rice seed production plots, seedlings are not all transplanted at the same time.
         For that reason, N application timing must be adjusted.
First split:
     Do not apply N to the R line rows until 5-7 days after the last R line is transplanted.
     Divide the first split between the R line rows and the A line rows in proportion to the field
         space allotted to each parent.

Second split:
    Apply the second split to the entire seed production plot.
    The second split should be applied 20-25 days after the last fertilizer application to the
      plot.

Third split:
Apply the remaining one-third to the entire seed production plot at maximum tillering.




                                                                                                  42
Adjusting Flowering Date
Synchronization of flowering date of parental
lines
      We try to synchronize flowering of parental lines by differential seeding.
      Weather fluctuations during the growing season and crop management practices may
       cause the parental lines to flower on different dates.
      When flowering is not synchronized, hybrid seed yield will be reduced.
      Flowering date of parental lines cannot be accurately predicted until the crop is at
       maximum tillering stage.

Panicle initiation and flowering date
Panicle initiation and flowering date
    Flowering date is predicted on the basis of panicle initiation.
    Panicle initiation begins at maximum tillering in all rice cultivars.
    Flowering occurs in all cultivars about 30 days after panicle initiation.
    The young panicle (panicle primordium) becomes visible (with a magnifying lens) within
       o 40-45 days of seeding in cultivars maturing in 95-100 days.
       o 50-52 days of seeding in cultivars maturing in 105-110 days.
       o 60-62 days of seeding in cultivars maturing in 115-120 days.
       o 65-70 days of seeding in cultivars maturing in 125-130 days.

How to observe panicle initiation
      Select the longest growing tiller (main tiller) and cut it at the base where stem and root
       join.
      Slit the stem lengthwise from the base up to the top of the tiller.
      Open the slit immediately above the nodal portion.
      Observe the developing panicle (preferably with a magnifying lens). It is about 1 mm
       long.




                                                                                                    43
Development stages of panicle formation to
flowering
The young panicle undergoes 10 developmental stages before it finally emerges out of the flag
leaf sheath.

Designation             Developmental stage Approx. Designation         Approx. panicle
                                             days before heading        length (mm)
I                       Panicle primordia    30                         0.2
II                      Primary branch       27                         0.4
                        primordia
III                     Secondary branch     24                         1.5
                        primordia
IV                      Stamen and pistil    20                         2
                        primordia
V                       Pollen mother cells  17                         10-25
VI                      Meiotic division     12                         80
VII                     Mature pollen        6                          190-250
VIII                    Ripe stage of pollen 4                          260
IX                      Completed spikelets  2-1                        270
X                       Flowering




                                                                                                44
Estimating flowering date by panicle primordium
stage
Estimating flowering date by panicle primordium stages
For complete flowering synchronization, the pollen parent should be one stage earlier than the
seed parent during stages I, II, and III of panicle development.
Both parents should be in the same stage during the 4 middle stages IV, V, VI, and VII.
The seed parent should be slightly earlier than the pollen parent during VIII, IX, and Xth stages of
panicle development.




                                                                                                  45
How to adjust flowering date of parental lines
showing 5-6 days difference
Presuming...
Pollen parent                                      Seed parent
Stage 1 indicating late flowering                  Stage 3 indicating early flowering

       Delay the flowering date of the seed parent
        o by spraying quick releasing nitrogen fertilizer (urea 2% concentration) immediately
            after observing that the panicle in the seed parent is at stage III.
       Advance the flowering date of the pollen parent
        o by spraying 1% solution of phosphate fertilizer immediately after observing the
            panicle development stage in the pollen parent, or
        o keep water standing in the field.

How to adjust flowering date of parental lines
showing a difference of more than a week
Presuming...
Pollen parent                                      Seed parent
Stage 1 indicating late flowering                  Stage 4 indicating early flowering

Remove the panicles from the main tiller of the seed parent.
    Spray 2% urea and also add nitrogenous fertilizer to the seed parent only to make
      unproductive, late tillers bear productive panicles and achieve synchronization of
      flowering.
    Advance the flowering date of the pollen parent
      o by spraying 1% solution of phosphate fertilizer immediately after observing the
          panicle development stage in the pollen parent, or
      o by keeping water standing in the field.




                                                                                                46
Flag Leaf Cutting
Crop stage for flag leaf clipping
     Flag leaves should be cut 1 or 2 days before heading.
     Flag leaf cutting enhances uniform pollen movement and wide dispersal of the pollen
      grains to give higher seed set.




Flag leaf clipping method
     First, cut the flag leaf of the main tiller just above the flag leaf joint.
     Use the portion cut from the main tiller as a guide in cutting the rest of the tillers in a
      plant. Flag leaves of other tillers will be cut 1/2 to
     2/3 from the top.
     Experienced growers may cut one-half to two-thirds of the blade of the flag leaf back from
      the top.
     Do not cut the flag leaves in plots infected with bacterial leaf blight, bacterial leaf streak,
      or sheath blight. The cut leaves can infect other plants, or contaminated tools used for
      flag leaf cutting can spread infection.
     Alternatively, flag leaf cutting of the infected area can be done after flag leaves have
      been cut from healthy plants in the plot.




                                                                                                  47
Gibberellic acid application
Why spray gibberellic acid?
       Gibberellic acid can also be written as GA3.
       We spray hybrid rice seed production plots with GA3 to:
        o adjust plant height of both parents.
        o increase the growth rate of secondary and tertiary tillers so that they bear panicles.

In the seed parent, GA3:
      enhances panicle exertion from the flag leaf.
      increases the duration of floret opening.
      increases the rate of stigma exertion and lengthens the duration of stigma receptivity.

Timing of application-crop growth stage
       Hybrid rice seed production plots are usually sprayed twice.
       The first spraying of GA3 is done when 15-20% of the tillers has started heading.
       The second spraying should be done 2 days after the first spraying, or when 35-40% of
        the panicles of the seed parent has emerged.




                                                                                                   48
Timing of application-weather conditions
     Spray in the afternoon on a sunny day. Do not spray if rain is expected within 24 hours.
     Spray on calm days to prevent spray from drifting onto nearby fields.
     Spraying on windy days wastes spray because it is carried away from the seed
      production plots.




                                                                                                 49
How to make GA3 solution general procedure
      GA3 is sold as a powder. It comes in purity levels of 100% pure and 90% pure. The purity
       of the GA3 powder controls the amount you use to make the spray solution.
      The concentration of GA3 mixed with water to make the spray solution is measured in
       parts per million (ppm). For example, 3 grams of GA3 dissolved in 50 liters of water will
       give 60 ppm concentration.
      Use 500 liters of water per hectare when spraying with a knapsack sprayer. Use 20 liters
       of water per hectare when spraying with an ultra-low volume sprayer. Use a
       correspondingly smaller amount of water for areas less than a hectare.
      The concentrations depend on the type of sprayer you use and whether you are doing
       the first spraying or the second spraying.

      GA3 Spray Concentration (ppm)
Spraying       Knapsack         Ultra-Low
                                Volume
First          60               500
Second         30               250


      GA3 powder will not dissolve in water. It must be dissolved in a small amount of 70%
       ethanol (grain alcohol) before it is mixed with water.
      A liquid dish detergent or laundry detergent should be added to the solution. The
       detergent makes GA3 stick to the leaf surface for more efficient coverage of the plants.

How to make GA3 solution amount required for
different size plots
How to use these charts:
    These two charts will help you select the right amount of GA3 to add to a given volume of
       water for the required concentration.
    There is one chart to follow when using a knapsack sprayer, and another when using an
       ultra-low volume sprayer.
    Each chart gives information for making the proper concentration for the first and second
       spraying. Be sure to use the correct amount of GA3 depending on the purity of the
       chemical.
    Always dissolve the GA3 powder in a small amount of 70% ethanol (grain alcohol) first,
       and then mix with the required amount of water.
    To make sure you understand how to use the charts, find the amount of GA3 needed to
       make up enough solution to spray a 2,000 m2 plot using knapsack sprayer. Assume you
       have GA3 of 90% purity and you want a 60 ppm concentration. According to the chart,
       you would need 6.7 grams of GA3 (dissolved in 70% ethanol) to make 100 liters of spray.




                                                                                                  50
Knapsack sprayer
Amount of GA3 in grams required for a given volume of water and given concentration of
solution. Use the appropriate number (GA3) under the 100% or 90% columns, depending on the
purity of chemical.
          2
Area (m )        Water          Concentration
                 vol(liter)
                              60 ppm                         30 ppm
                              100%           90%             100%           90%
1000           50             3.0            3.3             1.5            1.7
2000           100            6.0            6.7             3.0            3.3
4000           200            12.0           13.3            6.0            6.7
6000           300            18.0           20.0            9.0            10.0
8000           400            24.0           26.7            12.0           13.3
10000          500            30.0           33.3            15.0           16.7
Ultra-low volume sprayer
1000           2              1.0            1.1             0.5            0.6
1500           3              1.5            1.7             0.7            0.8
2000           4              2.0            2.2             1.0            1.1
2500           5              2.5            2.8             1.3            1.4
5000           10             5.0            5.6             2.5            2.8
7500           15             7.5            8.3             3.8            4.2
10000          20             10.0           11.2            5.0            5.6




                                                                                         51
How to make GA3 solution doing your own
computations
You can compute the amount of GA3 and water required for any size plot. For the example, we
assume:
    a GA3 source of 90% purity.
    a knapsack sprayer.
    a 2,000-m2 seed production plot.
    a 60 ppm concentration is desired.

GA3         Desired Concentration
Purity      Ultra-low sprayer   Knapsack sprayer
            500ppm 250ppm 60ppm          30ppm
90%         1.1        0.056    0.067    0.033
100%        1          0.5      0.06     0.03

        First, calculate the amount of water required to spray the plot. The volume of water
         required to spray 1 ha is 500 liters. We calculate the
      We then multiply the amount of water by the amount of GA3 of either 90% or 100% purity
         required for the desired concentration. Take that number from the table provided.
Since we are using a knapsack sprayer and assume a GA3 purity of 90%, we take the number
0.067. Multiply it by 100, the amount of water we calculated was required to spray a 2,000 m2
plot:
Remember to add about 5-10 ml of liquid detergent to every 50 liters of spray solution.
NOTE: In China application of higher dosage of GA3 has been observed to increase seed
yield in hybrid seed production plots.



Supplementary Pollination
Methods of supplementary pollination
        Supplementary pollination is artificially shaking the canopy of the pollen parent at
         flowering to increase cross pollination.
        Supplementary pollination
         o causes anthers to shed all of their pollen.
         o disperses pollen grains uniformly over the seed parent plants.
         o increases seed set in the seed parent.

        Supplementary pollination is done by
         o two persons pulling a 1-cm diameter rope across the two R lines.
         o one person stirring the canopy layer of the R lines with a bamboo stick, taking care
            not to break off the panicles at the neck.




                                                                                                  52
Timing of supplementary pollination
     Supplementary pollination is done on calm days when wind speed is so low (1-3 km/hour)
      it causes little or no movement of the crop canopy. Wind speed that low is not enough to
      disperse pollen uniformly to the seed parent.
     If there is enough wind (8-10 km/hour) to cause moderate movement in the crop canopy,
      supplementary pollination is not needed.
     Begin supplementary pollination in the morning, but not before the seed parent has
      started blooming. If the seed parent is blooming, begin as soon as the first florets of the
      pollen parent begin to open.
     Stir the canopy every 30 minutes until all blooming florets in the pollen parent are closed.
     Continue supplementary pollination even after the florets of the seed parent have closed,
      because exerted stigmas are still receptive to pollen.




Roguing
What is roguing and why is it necessary?
     Roguing is the removal of undesirable rice plants from hybrid seed production plots.
     Undesirable rice plants are plants in either the A line or R line rows that differ from plants
      that are true to type. They may be volunteer plants from an earlier crop or off-types.
     Roguing prevents off-types from cross pollinating with true-to-type A line plants and
      lowering the purity of the hybrid seed.
     Roguing ensures that the hybrid seed produced will be a cross between only the A line
      and R line parents. That in turn ensures that the commercial plantings of the hybrid seed
      produced will give high yields.
     High purity hybrid seed will increase your reputation as a seed grower.

Crop stage for roguing
     Roguing can be done at any time of the crop stage. Off-type rogues can be removed from
      the crop whenever they appear.
     The most important stages for roguing are:
     at maximum tillering.
     at flowering.
     just before harvest.




                                                                                                  53
Off types to be removed
At maximum tillering
     Remove any plants outside the rows.
     Remove plants that are considerably taller or shorter than the seed or the pollen parents.
     Remove plants that are off-type in leaf blade size or shape.
     Remove plants that are off-type in color of the leaf sheath or leaf collar.




At flowering and before harvest
At flowering
      Remove off-type plants that flower very early or very late.
      Remove plants that are off-type in leaf size, leaf angle, and panicle shape and size.
      Remove plants from the A line that have plump, yellow anthers and shed pollen. Plants in
       the A line should not have viable pollen.
      Remove plants with fully exserted panicles from the A line.
      Remove all diseased plants from the seed production plot.

Before harvest
    In A line rows, remove plants that have normal seed set.
    Remove off-types that have different grain characters from the normal A line plants. Look
       for differences in grain shape, grain size, or the presence or absence of awns.




                                                                                              54
Harvesting
Special considerations for harvesting hybrid rice
     Harvesting hybrid rice seed production plots is different from harvesting a rice grain crop.
     Harvest the R line first, and then harvest the A line.
     The A line harvest is the only one that can be sold as hybrid seed. The R line harvest
      may be sold as grain or kept for home use.
     The A line harvest and the R line harvest must be kept separate from each other during
      harvesting, threshing, drying, and bagging.

When to harvest
     Harvest when 90% of the grains in the main panicles of the A line plants are clear, firm,
      and straw colored. The rest of the grains should be in the hard dough stage.
     Harvest when seed moisture is less than 20%.
     Drain the hybrid seed production field 7-10 days before expected harvest. Draining the
      field makes the crop mature faster and helps to achieve uniform maturity in the crop.

Harvesting the B or R line
     Harvest all B or R line rows first.
     Harvest the plants manually by cutting them off at the base with a sickle or scythe.
     Remove the R line harvest and store it in a safe place for threshing later.
     Do not leave even one panicle in the field. It could be mixed with the A line harvest and
      reduce the purity of the hybrid seed.




                                                                                                  55
Harvesting the A line
     Rogue the A line rows one more time before harvest.
     Remove plants with normal seed set.
     Remove any other plants that appear to be off-types
     The A line can be harvested manually or with a mechanical combine. If a combine is
      used, it should have adjustable field speed and clearance to prevent field loss or grain
      damage.




                                                                                                 56
Threshing
Preparation for threshing
     During threshing, the seed parent and pollen parent harvests must be kept separate from
      each other. The seed parent should not get mixed with other seed or grain on the
      threshing floor or with any leftover in the thresher.
     All threshing equipment and the threshing floor should be thoroughly cleaned before
      starting threshing.
     New jute sacks should be available for bagging the seed.
     If new sacks are not available, then use clean used sacks. The used sacks must not
      contain any rice grains that could become mixed with the hybrid seed.
     Make two labels for each bag: one to place inside the bag and one to attach to the
      outside.
     Each label should contain the following information:
      o your name and address.
      o the name of the hybrid.
      o the location of the seed production field.
      o season.




                                                                                           57
Threshing the seed and pollen parent
Threshing the seed parent:
    Thresh the seed parent first to keep it from being mixed with any other seed.
    Thresh the seed manually with a hand flail on a threshing floor or with a manual or
       power-driven thresher.
    Dry the threshed seed of seed parent immediately.

Threshing the pollen parent:
The pollen parent should be threshed separately and used as grain. It should not be used as
seed.




Seed Drying
Why seed drying?
       Seeds can be safely stored when they have been dried to a moisture content of 13%.
       Drying helps seeds maintain their ability to germinate and their vigor for a longer period.
       Drying controls mold growth and the activity of other organisms that reduce the quality of
        stored grain.
       Drying reduces seed discoloration, which lowers the market value of the seed




                                                                                                 58
Seed drying methods-sun drying
      Seeds can be sun-dried on a threshing floor.
      Do not dry the seeds directly on the concrete threshing floor. Place them on jute bags or
       on a tarpaulin.
      Stir the seeds occassionally to ensure uniform drying.




Seed drying methods-forced air drying
      Seeds can be dried in a batch-type dryer by forced air heated to 40- 45 °C.
      Do not dry the seeds abruptly to 13% moisture content if the beginning seed moisture is
       higher than 20%.
      The seed layer in a batch-type dryer should not be more than 45 cm deep.



Processing Hybrid Rice Seed for Market
Cleaning and grading
The purpose of cleaning the seed is to:
    Remove impurities such as trash, leaves, broken seeds, sand or grit, etc.
    Remove weed seeds or those of other plant species.
    Remove immature, shriveled, unfilled, and empty spikelets.
    Seed can be cleaned manually by winnowing. Winnowing removes only light, chaffy
       material.
    An air screen machine not only cleans the seed but separates seed of uniform size from
       oversize and undersize seeds. The process of separating seeds of uniform size is known
       as grading.



                                                                                               59
     Air screen machines are normally too expensive for on-farm ownership. Cleaning and
      grading are usually done by public or private seed agencies that contract with seed
      growers for hybrid seed production.




Seed germination testing
     Before seeds can be packed and sold as hybrid seed, they must be tested for
      germination rate and purity.
     Public seed testing agencies normally do the testing and certification. The germination
      rate must be at least 85% in order for seed to be certified.
     Before taking your seed for testing, you can do your own germination test at home by
      following the instructions.

      1. Spread 200 seeds evenly over new or clean jute sacks that have been soaked in
         water.
      2. Cover the seeds with another wet jute sack.
      3. Roll up the jute sacks with the seeds inside and store them in the shade for 7 days.
         Keep the rolled sacks moist for the entire period. Do not let them dry out.
      4. Make three sets of 200 seeds.
      5. At the end of 7 days, count the normal seedlings that have developed. (Normal
         seedlings will have well-developed roots and shoots.)
      6. All three sets of germinated seeds should have a germination rate of at least 85%. A
         germination rate of 85% is 170 normal seedlings for each set of 200 seeds.

     If the germination rate of your seeds is 85% or higher, the seeds can be packed.




                                                                                                60
Packing and labeling the seed
     Pack your seed in clean, preferably new, jute bags.
     If you store your seeds in used bags, you should disinfect the bags to protect the seed
      from insects that could attack the seed during storage.
     Follow these steps to disinfect used bags.
      1. Turn the bags inside out and shake them thoroughly so no seeds of any kind stick to
           the inside of the bag.
      2. Soak the bags for 10 minutes in a 0.15% solution of malathion. (Make the solution by
           mixing 1 part malathion 50 EC in 300 parts water.)
      3. Dry the bags under shade before filling them with seed.

     Do not pack your seed if the moisture content is more than 13%. The seed could spoil
      during storage.
     Make two labels for each bag - one to place inside the bag and one to attach to the
      outside.
     Each label should contain the following information:
      1. your name and address.
      2. the name of the hybrid.
      3. the location of the seed production field.
      4. season.




                                                                                             61
Citation
The International Rice Research Institute (IRRI) was established in 1960 by the Ford and
Rockefeller Foundations with the help and approval of the Government of the Philippines. Today
IRRI is one of the 16 nonprofit international research and training centers supported by the
Consultative Group on International Agricultural Research (CGIAR). The CGIAR is sponsored by
the Food and Agriculture Organization of the United Nations, the International Bank for
Reconstruction and Development (World Bank), and the United Nations Development
Programme (UNDP). The CGIAR consists of 50 donor countries, international and regional
organizations, and private foundations.

IRRI receives support, through the CGIAR, from a number of donors including the Asian
Development Bank, the European Economic Community, the Ford Foundation, the International
Development Research Centre, the International Fund for Agricultural Development, the OPEC
Special Fund, the Rockefeller Foundation, UNDP, the World Bank, and the international aid
agencies of the following governments: Australia, Belgium, Brazil, Canada, China, Denmark,
Finland, France, Germany, India, Iran, Italy, Japan, Republic of Korea, Mexico, The Netherlands,
New Zealand, Norway, the Philippines, Saudi Arabia, Spain, Sweden, Switzerland, United
Kingdom, and United States.

The responsibility for this publication rests with the International Rice Research Institute.

Copyright © International Rice Research Institute 1992. All rights reserved.

Except for quotations of short passages for the purpose of criticism and review, no part of this
publication may be reproduced, stored in retrieval systems, or transmitted in any form or by any
means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of
IRRI. This permission will not be unreasonably withheld for use for noncommercial purposes.
IRRI does not require payment for the noncommercial use of its published works, and hopes that
this copyright declaration will not diminish the bona fide use of its research findings in agricultural
research and development.

The designations employed in the presentation of the material in this publication do not imply the
expression of any opinion whatsoever on the part of IRRI concerning the legal status of any
country, territory, city, or area, or of its authorities, or the delimitation of its frontiers or boundaries.




                                                                                                          62
Index
            1
10
  bags ........................................................................................................................................... 60
100
  levels ......................................................................................................................................... 49
100-m ............................................................................................................................................ 26
10-day ..................................................................................................................................... 21, 37
10-day longer growth duration ............................................................................................. 22, 33
10-day shorter growth duration ........................................................................................... 22, 32
15-cm ............................................................................................................................................ 38
165-cm .......................................................................................................................................... 32
  Leave ......................................................................................................................................... 32
1-cm .............................................................................................................................................. 51
  pulling ....................................................................................................................................... 51
            2
2
  000 m2 ................................................................................................................................. 49, 51
    spray ................................................................................................................................ 49, 51
  000-m2 ....................................................................................................................................... 51
200
  sets ............................................................................................................................................ 59
21and 27 ................................................................................................................................. 32, 33
21-day-old ..................................................................................................................................... 28
  Transplanting ........................................................................................................................... 28
24
  water .......................................................................................................................................... 19
250ppm ......................................................................................................................................... 51
            3
30-cm ................................................................................................................................ 30, 32, 33
  Leave ............................................................................................................................. 30, 32, 33
30ppm ........................................................................................................................................... 51
3-day ............................................................................................................................................. 21
            4
40
  heated ........................................................................................................................................ 58
4th ................................................................................................................................................. 30
            5
500ppm ......................................................................................................................................... 51
            6
60 ppm .......................................................................................................................................... 49
  want ........................................................................................................................................... 49
60ppm ........................................................................................................................................... 51




                                                                                                                                                    63
            7
75-cm ...................................................................................................................................... 30, 33
  Leave ................................................................................................................................... 30, 33
            8
85
  rate ............................................................................................................................................. 59
8-row ............................................................................................................................................. 32
  transplanting ............................................................................................................................ 32
            9
90
  GA3 ............................................................................................................................................ 49
            A
Adjust ...................................................................................................................................... 20, 45
Age ................................................................................................................................................ 28
  Seedling .................................................................................................................................... 28
Agricultural Development ........................................................................................................... 61
  International Fund .................................................................................................................... 61
Agriculture Organization ............................................................................................................ 61
  United Nations .......................................................................................................................... 61
Application-crop growth stage ................................................................................................... 47
  Timing ....................................................................................................................................... 47
Application-weather conditions ................................................................................................. 48
  Timing ....................................................................................................................................... 48
Approx .......................................................................................................................................... 43
Asian Development Bank ........................................................................................................... 61
  including ................................................................................................................................... 61
Assistance ...................................................................................................................................... 5
  T 5
Assume ......................................................................................................................................... 51
  GA3 ............................................................................................................................................ 51
Australia ....................................................................................................................................... 61
            B
B 13, 20, 25, 28, 29, 30, 54
  called ......................................................................................................................................... 13
  Harvesting ................................................................................................................................. 54
  row ............................................................................................................................................. 29
  seeding ...................................................................................................................................... 25
  seedings .................................................................................................................................... 25
  Transplanting ..................................................................................................................... 28, 30
B line ............................................................................................................................................. 30
Bags .............................................................................................................................................. 60
  10 ............................................................................................................................................... 60
Barrier isolation ........................................................................................................................... 27
Bears ............................................................................................................................................... 6
  spikelets ...................................................................................................................................... 6
Before harvest.............................................................................................................................. 53
Behavior ....................................................................................................................................... 30
  Flowering .................................................................................................................................. 30
Belgium ......................................................................................................................................... 61
Brazil ............................................................................................................................................. 61



                                                                                                                                                   64
            C
C 58
Called ............................................................................................................................................ 13
  B 13
  CMS ........................................................................................................................................... 13
Canada .......................................................................................................................................... 61
CGIAR ........................................................................................................................................... 61
Change .......................................................................................................................................... 35
Characteristics ....................................................................................................................... 15, 29
  CMS ........................................................................................................................................... 15
  R 29
China ......................................................................................................................................... 5, 61
China application ......................................................................................................................... 51
Choice ........................................................................................................................................... 17
  parents ...................................................................................................................................... 17
Citation ......................................................................................................................................... 61
CMS ............................................................................................................................. 13, 15, 20, 25
  called ......................................................................................................................................... 13
  characteristics .......................................................................................................................... 15
  crossed ..................................................................................................................................... 15
  maintaining ............................................................................................................................... 13
  multiplying ................................................................................................................................ 20
CMS line........................................................................................................................................ 15
  Desirable characteristics ........................................................................................................ 15
CMS multiplication ...................................................................................................................... 25
  times .......................................................................................................................................... 25
Completed spikelets .................................................................................................................... 43
Construct 5-10-cm ....................................................................................................................... 18
Control diseases .......................................................................................................................... 40
Control weeds .............................................................................................................................. 39
Copublication ................................................................................................................................. 5
Copyright © International Rice Research Institute 1992 ......................................................... 61
Crop stage .............................................................................................................................. 46, 52
  flag leaf ...................................................................................................................................... 46
Crossed ........................................................................................................................................ 15
  CMS ........................................................................................................................................... 15
Cultivar ................................................................................................................................... 15, 26
Cultivars ........................................................................................................... 8, 25, 26, 27, 41, 42
            D
D 35
Date ................................................................................................................................... 42, 44, 45
  flowering ................................................................................................................................... 42
  parental lines ...................................................................................................................... 42, 45
Days difference ............................................................................................................................ 45
Denmark ....................................................................................................................................... 61
Desirable characteristics ...................................................................................................... 15, 16
  CMS line .................................................................................................................................... 15
  maintainer ................................................................................................................................. 16
Desired Concentration ................................................................................................................ 51
Determine ..................................................................................................................................... 21
Development ................................................................................................................................ 61
Development stages .................................................................................................................... 43
  panicle formation ..................................................................................................................... 43
Difference ..................................................................................................................................... 45



                                                                                                                                                  65
  more .......................................................................................................................................... 45
Different size plots ...................................................................................................................... 49
  make GA3 solution amount required ..................................................................................... 49
Differential .............................................................................................................................. 20, 25
Dissolve ........................................................................................................................................ 49
  GA3 ............................................................................................................................................ 49
Distance isolation ........................................................................................................................ 26
During ........................................................................................................................................... 44
  VIII .............................................................................................................................................. 44
            E
Easy-to-understand ....................................................................................................................... 5
European Economic Community ............................................................................................... 61
Exsert ............................................................................................................................................ 13
Exserted ............................................................................................................................ 15, 16, 53
            F
F1 ............................................................................................................................. 5, 12, 13, 15, 17
Factors .......................................................................................................................................... 29
Fertilizer management ................................................................................................................ 41
Finland .......................................................................................................................................... 61
Flag leaf ........................................................................................................................................ 46
  Crop stage ................................................................................................................................ 46
Flowering .......................................................................................................................... 30, 42, 44
  behavior .................................................................................................................................... 30
  date ............................................................................................................................................ 42
  synchronization........................................................................................................................ 44
Food .............................................................................................................................................. 61
Ford ............................................................................................................................................... 61
Ford Foundation .......................................................................................................................... 61
Foreword ........................................................................................................................................ 5
France ........................................................................................................................................... 61
            G
GA3 ................................................................................................................................... 47, 49, 51
  90 ............................................................................................................................................... 49
  assume ...................................................................................................................................... 51
  dissolve ..................................................................................................................................... 49
  spraying .................................................................................................................................... 47
GA3 Purity .................................................................................................................................... 51
GA3 Spray Concentration ........................................................................................................... 49
Germany ....................................................................................................................................... 61
Gibberellic .................................................................................................................................... 47
Government.................................................................................................................................. 61
  Philippines ................................................................................................................................ 61
Grain ............................................................................................................................................... 7
            H
Harvest .................................................................................................................................... 54, 55
  B 54
  line ............................................................................................................................................. 55
  R 54
Heated ........................................................................................................................................... 58
  40 ............................................................................................................................................... 58
Hills ............................................................................................................................................... 39



                                                                                                                                                    66
Hybrid rice .................................................................................................................................... 54
Hybrid rice seed ........................................................................................................................... 12
Hybrid seed production .............................................................................................................. 17
            I
II 43, 44
III 43, 44, 45
Inbred rice seed ........................................................................................................................... 11
Including ....................................................................................................................................... 61
    Asian Development Bank ........................................................................................................ 61
India .............................................................................................................................................. 61
Insect-pests .................................................................................................................................. 40
International Bank ....................................................................................................................... 61
    Reconstruction ......................................................................................................................... 61
International Development Research Centre ............................................................................ 61
International Fund ....................................................................................................................... 61
    Agricultural Development ....................................................................................................... 61
International Rice Research Institute ........................................................................................ 61
Intially ............................................................................................................................................. 5
Iran ................................................................................................................................................ 61
IRRI ............................................................................................................................................ 5, 61
    part ............................................................................................................................................ 61
Italy ................................................................................................................................................ 61
IV 43, 44
IX 43, 44
            J
Japan ............................................................................................................................................ 61
            K
K 41
Km/hour ........................................................................................................................................ 52
Korea ............................................................................................................................................. 61
  Republic .................................................................................................................................... 61
            L
Labeling ........................................................................................................................................ 60
  seed ........................................................................................................................................... 60
Layer ............................................................................................................................................. 51
  R 51
Layout ........................................................................................................................................... 28
Leave ................................................................................................................................. 30, 32, 33
  165-cm ....................................................................................................................................... 32
  30-cm ............................................................................................................................. 30, 32, 33
  75-cm ................................................................................................................................... 30, 33
Levels ............................................................................................................................................ 49
  100 ............................................................................................................................................. 49
Line ............................................................................................................................................... 55
  Harvesting ................................................................................................................................. 55
Line--one B ................................................................................................................................ 25
Line--one B line--two ................................................................................................................ 30
Line--one R ................................................................................................................................ 23
Line--one R line--three ............................................................................................................. 22




                                                                                                                                                     67
            M
M 18, 26, 27
M2 ............................................................................................................................................ 19, 49
Maintainer ..................................................................................................................................... 16
  Desirable characteristics ........................................................................................................ 16
Maintainer line.............................................................................................................................. 13
Maintaining ................................................................................................................................... 13
  CMS ........................................................................................................................................... 13
Make GA3 solution amount required ......................................................................................... 49
  different size plots ................................................................................................................... 49
Make GA3 solution doing ........................................................................................................... 51
Make GA3 solution general procedure ...................................................................................... 49
Malathion ...................................................................................................................................... 60
Malathion 50 EC ........................................................................................................................... 60
Male sterile line ............................................................................................................................ 13
Managing ...................................................................................................................................... 20
  seedbed ..................................................................................................................................... 20
Many seedlings per hill ............................................................................................................... 28
Methods .................................................................................................................................. 46, 51
  supplementary pollination ...................................................................................................... 51
Methods-forced air ...................................................................................................................... 58
Methods-sun ................................................................................................................................ 58
Mexico........................................................................................................................................... 61
Modify row .................................................................................................................................... 38
Modify row ratios ......................................................................................................................... 38
More .............................................................................................................................................. 45
  difference .................................................................................................................................. 45
Multiplying .................................................................................................................................... 20
  CMS ........................................................................................................................................... 20
            N
N 41
  R 41
N application ................................................................................................................................ 41
Necessary ..................................................................................................................................... 52
New Zealand ................................................................................................................................. 61
Nonindustrialized........................................................................................................................... 5
Norway .......................................................................................................................................... 61
NOTE ....................................................................................................................................... 34, 51
NPK ......................................................................................................................................... 18, 41
Number ........................................................................................................... 22, 23, 25, 30, 32, 33
  seedings ........................................................................................................................ 22, 23, 25
  transplantings .............................................................................................................. 30, 32, 33
            O
Observe panicle initiation ........................................................................................................... 42
Occassionally............................................................................................................................... 58
Off types ....................................................................................................................................... 53
OPEC Special Fund ..................................................................................................................... 61
Own computations ...................................................................................................................... 51
            P
P 41
Panicle formation......................................................................................................................... 43



                                                                                                                                                  68
  Development stages ................................................................................................................ 43
Panicle initiation .......................................................................................................................... 42
Panicle primordia......................................................................................................................... 43
Panicle primordium stage ........................................................................................................... 44
Panicles exsert....................................................................................................................... 13, 15
Parental lines ......................................................................................................................... 42, 45
  date ...................................................................................................................................... 42, 45
Parents .......................................................................................................................................... 17
  Choice ....................................................................................................................................... 17
Part ............................................................................................................................................ 8, 61
  IRRI ............................................................................................................................................ 61
  seed ............................................................................................................................................. 8
Philippines.................................................................................................................................... 61
  Government .............................................................................................................................. 61
Plant spacings ............................................................................................................................. 38
Pollen ............................................................................................................................................ 45
Pollen parent ........................................................................................................ 22, 23, 32, 33, 57
Ppm ......................................................................................................................................... 49, 51
Pregerminating seeds ................................................................................................................. 19
Preparation ................................................................................................................................... 56
Primordia ...................................................................................................................................... 43
Primordium ............................................................................................................................. 42, 44
Process ......................................................................................................................................... 10
  seed formation ......................................................................................................................... 10
Proportion .................................................................................................................................... 35
  R line ......................................................................................................................................... 35
Pulling ........................................................................................................................................... 51
  1-cm ........................................................................................................................................... 51
            R
R 15, 19, 20, 21, 22, 23, 25, 28, 29, 30, 32, 33, 35, 37, 38, 39, 41, 51, 52, 54
  Characteristics ......................................................................................................................... 29
  Harvest ...................................................................................................................................... 54
  layer ........................................................................................................................................... 51
  N 41
  Remove ..................................................................................................................................... 54
  rows ........................................................................................................................................... 32
  seeding .............................................................................................................. 21, 22, 23, 35, 37
  seedings .................................................................................................................................... 22
  take ............................................................................................................................................ 29
  Transplanting ..................................................................................................................... 32, 33
R line ............................................................................................................... 21, 30, 32, 33, 35, 54
  proportion ................................................................................................................................. 35
R line twice ................................................................................................................................... 37
  Seed ........................................................................................................................................... 37
R line--one .................................................................................................................................... 33
Rate ............................................................................................................................................... 59
  85 ............................................................................................................................................... 59
Reconstruction ............................................................................................................................ 61
  International Bank .................................................................................................................... 61
Remove ................................................................................................................................... 53, 54
  R 54
Republic ........................................................................................................................................ 61
  Korea ......................................................................................................................................... 61
Requirements ............................................................................................................................... 25
Restorer line ........................................................................................................................... 15, 16


                                                                                                                                                   69
Retransplant ................................................................................................................................. 39
Rice plant ........................................................................................................................................ 6
Ricefields ...................................................................................................................................... 25
Rockefeller Foundations ............................................................................................................. 61
Rola ................................................................................................................................................. 5
Row ratio ...................................................................................................................................... 29
Rows ....................................................................................................................................... 29, 32
  B 29
  R 32
            S
Same growth duration ........................................................................................................... 23, 34
Saudi Arabia ................................................................................................................................. 61
Seed ...................................................................................... 7, 8, 21, 22, 23, 25, 35, 37, 57, 58, 60
  B 25
  labeling ...................................................................................................................................... 60
  Parts ............................................................................................................................................ 8
  R 21, 22, 23, 35, 37
  R line twice ............................................................................................................................... 37
  Threshing .................................................................................................................................. 57
Seed formation............................................................................................................................. 10
  Process ..................................................................................................................................... 10
  Stages ....................................................................................................................................... 10
Seed germination......................................................................................................................... 59
Seed parent ................................................................................................................ 22, 23, 32, 33
Seedbed .................................................................................................................................. 18, 20
  Managing .................................................................................................................................. 20
Seedbed preparation ................................................................................................................... 18
Seedings ......................................................................................................... 22, 23, 25, 32, 33, 35
  B 25
  Number .......................................................................................................................... 22, 23, 25
  R 22, 23, 35
Seedling ........................................................................................................................................ 28
  age ............................................................................................................................................. 28
Semidwarf....................................................................................................................................... 5
Sesbania rostrata......................................................................................................................... 27
Sets ............................................................................................................................................... 59
  200 ............................................................................................................................................. 59
Sow pregerminated ..................................................................................................................... 19
Spain ............................................................................................................................................. 61
Special considerations ............................................................................................................... 54
Spikelet ............................................................................................................................... 9, 11, 29
Spikelets ........................................................................................................... 6, 11, 15, 16, 30, 58
  bears ............................................................................................................................................ 6
Spraying ........................................................................................................................... 47, 49, 51
  2
    000 m2 ............................................................................................................................. 49, 51
  GA3 ............................................................................................................................................ 47
Stages ........................................................................................................................................... 10
  seed formation ......................................................................................................................... 10
Supplementary pollination ................................................................................................... 51, 52
  Methods .................................................................................................................................... 51
  Timing ....................................................................................................................................... 52
Sweden ......................................................................................................................................... 61
Switzerland ................................................................................................................................... 61
Synchronization ......................................................................................................... 20, 42, 44, 45


                                                                                                                                                    70
   flowering ................................................................................................................................... 44
            T
T5
  assistance ................................................................................................................................... 5
Take ............................................................................................................................................... 29
  R 29
The Netherlands........................................................................................................................... 61
Threshing ..................................................................................................................................... 57
  seed ........................................................................................................................................... 57
Time isolation............................................................................................................................... 26
Times .................................................................................................................... 21, 25, 47, 48, 52
  application-crop growth stage................................................................................................ 47
  application-weather conditions .............................................................................................. 48
  CMS multiplication ................................................................................................................... 25
  supplementary pollination ...................................................................................................... 52
Today IRRI .................................................................................................................................... 61
Transplant R ........................................................................................................................... 32, 33
Transplanting ............................................................................................................. 27, 28, 30, 32
  21-day-old ................................................................................................................................. 28
  8-row .......................................................................................................................................... 32
  B 28, 30
  R 32, 33
Transplantings ................................................................................................................. 30, 32, 33
  Number .......................................................................................................................... 30, 32, 33
            U
Ultra-Low Volume ........................................................................................................................ 49
UNDP ............................................................................................................................................. 61
United Kingdom ........................................................................................................................... 61
United Nations ............................................................................................................................. 61
  Agriculture Organization ......................................................................................................... 61
United Nations Development Programme ................................................................................ 61
United States ................................................................................................................................ 61
            V
VI 43, 44
VII ............................................................................................................................................ 43, 44
VIII ........................................................................................................................................... 43, 44
   during ........................................................................................................................................ 44
            W
W.H. ................................................................................................................................................. 5
Want .............................................................................................................................................. 49
 60 ppm ....................................................................................................................................... 49
Water ............................................................................................................................................. 19
 24 ............................................................................................................................................... 19
Water vol....................................................................................................................................... 49
Week ............................................................................................................................................. 45
Why ............................................................................................................................................... 52
Why seed ................................................................................................................................ 18, 57
Why spray gibberellic acid ......................................................................................................... 47
Why transplant ............................................................................................................................. 27
World Bank ................................................................................................................................... 61




                                                                                                                                                    71
            X
Xth ................................................................................................................................................. 44




                                                                                                                                                    72

				
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