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Accelerated Seed Aging and Viability Technique

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Accelerated Seed Aging and Viability Technique Powered By Docstoc
					      Effect of priming on seed
    longevity and water sorption
              isotherms
                  Ian P. Wood, Fiona R. Hay

Seed Conservation Department, Royal Botanic Gardens Kew, UK
              Presentation at the ISTA Seed Symposium
                               June 2010
          Presentation outline
• Background to the study

• Experimental: Rhododendron griersonianum
   Priming
   Seed ageing
   Moisture sorption and desorption isotherms

• Conclusions
Can we improve seed longevity?



                    60 % RH @ 45 ºC
       Priming and seed longevity

• Seed longevity?
    Low-vigour cauliflower seeds
                                       Powell et al., 2000
    High-vigour cauliflower seeds

    Immature or aged foxglove seeds
    Non-aged foxglove seeds           Butler et al., 2009
     collected at storage maturity
                 Experimental – M&M
• Rhododendron griersonianum seeds
harvested 6 Jan, 3 Feb, 2 Mar 2004
• Stored at 15 % RH, 15 °C
• Samples primed: -1.5 MPa PEG for
3 d, dark, 20 °C
• Experimental storage of non-primed
(“control”) and primed seeds: 60 %
RH, 45 °C
• Samples tested for germination at
regular intervals
• Moisture content determination
 Experimental – Results

                    NEDs:
                             p
                    v  Ki 
                             σ
          Primed    Ellis and Roberts (1980)



                    Percentage:
                                     p
                   %v  100   K i  
                                     σ
Control
 Experimental – Results

                              Percentage:
                                                  p
                           %v  100  Cv   K i  
                                                  σ
          Primed
                   Control  Primed
                   • Initial germination 
                   • Cv significant (0.89)
                   • Ki  from 0.4-1.3 to 3.8 NED
Control            • σ  from 2.2 to 3.1 days
                   • p50  4- to 15-fold
                   Experimental – Results
• Primed seeds had a lower water content in experimental storage

                       Collection date      Storage WC
       Treatment
                                            (g g-1 d. wt)
                         6 January         0.079 [± 0.0006]
         Control         3 February        0.075 [± 0.0011]
                          2 March          0.073 [± 0.0020]
                         6 January              0.053
         Primed          3 February        0.056 [± 0.0005]
                          2 March          0.054 [± 0.0012]
     Priming, seed longevity, and seed
                 moisture
• Effect of priming on mung bean seeds
    Seed longevity
    Weakly bound water                       Sun et al., 1997
    Stongly bound and multimolecular water


• Effect of priming on lettuce seeds
    Sensitivity to moisture content during   Hill et al., 2007
     controlled deterioration
                     Experimental – M&M

    seeds harvested 6 January and
• For
2 March
• Automated water sorption and
desorption isotherm determination at
45 °C
• Fitting of the D’Arcy-Watt equation
                                Dry-seed
     K ' K /  O               k ' k /  O
WC                c /  O 
     1  K /  O              1  k /  O    www.hidenisochema.com
     Experimental – Results




Control
          Primed
Experimental – Results


             Effect of priming:
             number of strong water
             binding sites 
Experimental – Results


             Effect of priming:
             number of weak water
             binding sites 
Experimental – Results


             Effect of priming:
             number of
             multimolecular water
             binding sites 
Experimental – Results

                   Priming...

                    weakly bound
                   water =  longevity
Control            ( σ)
          Primed
                     Conclusions
• Priming   seeds of Rhododendron griersonianum
    Repair resulted in higher initial germination and
   a ‘rejuvenation’ of the competent seeds (increase
   in Ki)
    Changes in moisture sorption properties, in
   particular a decrease in the amount of weakly
   bound water, resulted in a slowing in the rate of
   viability loss (increase in σ)
    Effects of harvest date on seed longevity not
   evident after priming
             Thanks to …
Colleagues of the Millennium Seed Bank Partnership
         Experimental – Further work

• Target seed-lots of   Species                       p50 (days)
  other Ericaceae                               C     P0     P14   P0,
  species expected                                                      1
                                                                        4
  to be short-lived     Arbutus andrachne      24.3    -     15.1 18.3
                        Erica quadrangularis   7.9    7.0     -     -
                        Harrimanella           9.0     -     8.1    -
                          stelleriana
                        Kalmia latifolia       37.4 20.5 27.8 14.1
                        Lyonia mariana         35.2 44.3 40.6 42.1
                        Rhododendron           8.6    11.8   9.1   11.7
                          groenlandicum
                                                                          Species                     % change in p50

                            Can we improve                                                            in response to
                                                                                                          priming

                                                                          Amaranthus caudatus               -26
                            seed longevity?                               Campanula rapunculoides           +9
                                                                          Crassula clavata                  0

                  100                                                     Damasonium alisma                +21
                                                                          Dasylirion lucidum                0

                  80                                                      Epilobium ciliatum               +64
                                                                          Ficus exasperata                  0
                                                                          Filipendula vulgaris              0
Germination (%)




                  60
                                                                          Gallium mollugo                  +23
                                                                          Geranium lucidum                  -53
                  40
                                                                          Hyptis suavelolens                0
                                                                          Nicotiana glutinosa               0
                  20
                             Epilobium ciliat um                          Nicotiana tabacum                +70
                                        Cont rol
                              Primed af t er 12 d                         Oenothera cf. fallax              0
                   0
                        0    12       24        36   48    60   72   84   Oxychloris scariosa              +66
                                         t
                                        S orage period (days)             Portulaca oleracea                -45
                                                                          Primula cortusoides              +28
                                                                          Pycnostachus deflexifolia         -18
                                                                          Rumex crispus                    +60
                                                                          Sagina procumbens                 0
                                                                          Usteria quineensis                0

				
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posted:6/28/2012
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