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EGO Trial Results Summary

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EGO Trial Results Summary Powered By Docstoc
					HTW Dresden
Prof. Dr. F.-G. Schröder
University of Applied Science
Pillnitzer Platz 2
01326 Dresden




Cucumber grown in Fytocell slabs


MATERIAL AND METHODS
        The experiments with cucumber were carried out at the University of Applied
Science Dresden (Germany) in summer 2004. To investigate the plant growth and
root zone, a hydroponic system with standard drip irrigation and different substrates
a) rock wool and b) „Fytocell‟ was used. All substrates were used like in commercial
practice “Rockwool” and Fytocell are available as a slab. The plant density was 1.4
plants/m.
        The climate and the nutrient solution supply in the climate cabins was
monitored by computer. A standard nutrient solution (Sonneveld and Straver, 1988)
was used adjusting EC and pH. The irrigation control was based on time and
radiation, independent of the substrate. The bending technique of roses was used.

        For analyses of carbon dioxide (CO2) and dissolved oxygen (DO) different
methods were used. For analyses of carbon dioxide a gas sampling system was used
to get gas samples from the root zone. The gas sampling cells of 40 ml were air tight
at one end and the other and closed with a tape so a plastic syringe could used to take
air samples. CO2 gas samples of 20 ml were analyzed with an infrared (IR) sensor
Multiwarn II (Dräger, 2004).
        The dissolved oxygen (DO) was measured in substrates with a new fiber optic
mini sensor and the “Fibox 2” device (PreSens, 2004), which allows a online
measurements in situ monitored by computer. The principle of the measurement is
based on the effect of dynamic luminescence quenching by molecular Oxygen. The
collision between the luminophore in its excited state and the oxygen results in
radiation less deactivation. A relation exists between the oxygen concentration in the
sample and the luminescence intensity. The oxygen results, representing the dissolved
oxygen in solution, as percentage of dissolved oxygen saturation, at the surface of the
sensor. The small cylindrical mini sensor was inserted into the substrates about 10 cm
deep.
        The cylinder was located at 2 heights within the slabs (3 cm and 7 cm from the
bottom). To get correct results, the sensor is used with temperature compensation to
minimize temperature gradients.
        Measurement of oxygen and carbon dioxide was done in each substrate at the
same time of the day. Analysis of variance was carried out and Turkey Test at p<0.05
was used for comparison of means.
RESULTS AND DISCUSSION
       The objective of this study was to get more information about the root zone,
mainly the gas composition in substrates and their influence on plant growth, yield
and nutrient uptake.
The following figures showing all results of the tests.


         length of plants (cm)
    70
    60
    50
    40                                                            Fytocell
    30       a
                                                                  Rockwool
                      b
    20
    10
     0
             29/30        30/31       31/32          32/33
                            week in 2004



Figure 1. Plant growth per week (absolute).

Figure 2. Total length of plants (Steinwolle is Rockwool).


     total length of plants (cm)                  Steinwolle         Fytocell


  250
  200
  150
  100
   50
    0
                 29         30             31                32        33
                                           week
         number of leafs                      Steinwolle           Fytocell



  25
  20
  15
  10
    5
    0
            29             30            31            32            33
                                       week




Figure 3. Total number of leafs.

CO2-concentration (%) during the day 0,00,10,20,30,40,50,60,708:0009:00 10:0011:0012:0013:00 14:0015:0016:0017:00F




Figure 4. CO2-concentration in the root zone measured in the slab Fytocell (FC)
and Rockwool (G) at 2 heights a) top (7 cm from the floor) and b) bottom
(3 cm from the floor).
Oxygen (DO) % during the day 9092949698100102104106108 1234567891011121314151617181920212223FC topFC bottomG




Figure 4. O2-concentration in the root zone measured in the slab Fytocell (FC)
and Rockwool (G) at 2 heights a) top (7 cm from the floor) and b) bottom
(3 cm from the floor).


      Yield (kg/plant)
  8
                               a
  7
                                                 b
  6
  5
  4
  3
  2
  1
  0
                           fytoCell   1      Rockwool



Figure 5. Total yield of cucumber in both substrates.

Figure 6. Specific root length of cucumber in both substrates.


          spec. Root length (cm/g dry matter)

      300
      250
      200
      150
      100
       50
        0
                         Fytocell         spez          Rockwool
Plant growth and yield
       The plant growth of cucumber grown in Fytocell was better than in rockwool
(standard). The yield of cucumber was determined as number of marketable fruits.
The yield in Fytocell was significantly higher than in rockwool.


Carbon dioxide
        Gas sampling at two heights in slabs from the root zone did function well,
results ranged from 0,1 to 0,6 %. Results are significant between the different
substrates and the measurement spots within one substrate. The highest concentration
was found in Fytocell.


Dissolved oxygen
        The new method of monitoring the oxygen level in substrates via fiber optic
sensors did function well. Results describe the daily time course (24 h online) of O2-
concentrations in solution surround the roots in substrates under greenhouse
conditions. Analysis of variance was not carried out and used for comparison of
substrates.

In general, the daily time course is influenced by the plant activity (radiation) and the
irrigation schedule. The lowest O2-level was determined during the daytime, if the
uptake of plant is high due to radiation and higher substrate temperatures. Each
irrigation impulse led to a straight increase of O2-level.

        The time course of oxygen level is decreased during the day and increasing in
the night. The results, which are presented, are representing the specific substrate
properties (porosity, water holding capacity or material). In Fytocell the O2-
concentration was higher at night and lower during the day compared with rockwool.
That means at night the water content in Fytocell is lower too and during the day the
roots in Fytocell are consuming more oxygen, the roots are more active in this case.
Low O2-concentrations are a result of oxygen consumption or respiration, because at
the same time high CO2 -concentration are measured at the same relation.

The artifact of oxygen deficiency correlating with low yield or quality wasn‟t found
during the experiment.

				
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posted:4/26/2010
language:English
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