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154
Productivity of winter-somn chickpeas
Tota!
Seed above-ground blarvcst 100-seed Pods per Empty
Site Yieldt drymatter at hndex weight plant pods
(t/ha) harvest (t/ha) (No.) (%)
Jindcress
ILC 482 4.20 7.91 0.531 24,7 72.6 17.2
ILC 72 267 6.66 0.401 25,0 44.7 22.5
ILC 72 (Dense*) 3.24 8.38 0.387 25.7 24.9 21.5
ILC 482 (SS) 1.88 3.29 0.571 23.4 31.1 22.4
Tel Hadya
ILC 482 2.09 3.55 0.589 27.0 27.6 4.6
ILC 72 1.33 3.16 0.421 26.5 17.0 12.7
ILC 72 (Dense*) 1.38 3.87 0.357 25.7 9.3 13.2
ILC 482 (SS) 0.80 1.56 0.512 23.21 17.1 17.5
Brida
ILC 482 1.00 2.3o 0.424 28.1 13.7 6.7
ILC 72 0.31 1.59 0.195 20.5 9.6 46.4
ILC 72 (Dense*) 0.28 2.13 0.131 17.3 5.6 51.9
ILC 482 (SS) 0.74 1.37 0.540 19.2 17.1 20.1
t = Seed yields adjusted for minor insect damage.
* = Stand density approximately 600,000 pl/ha.
(SS) = Spring-sown crop from companion experiment.
precipitation received in the season from 456 mm to 277 mm (Table 3) reduced
seed yield considerably. The mechanisms by which this gross effect is exper­
ienced are somewhat diverse and complex, and precise quantification of individual
effects is, at this stage in the experimental analysis, difficult to achieve.
However, two mechanisms appear to be prominent in causing yield reductiom
1. It has been shown in Table 2 that maximum canopy development was
severely affected by location and that complete cover was only achieved at
Jindiress. This directly implies that the proportion of incident radiant energy
intercepted was reduced and total drymatter production levels were if,consequence
lower at the two drier sites. The reduced canopy development may
have resulted directly from an inability in the crop to meet short-term
atmospheric demand for moisture, thus experiencing a consequent retardation
of photosynthetic activity. Alternatively, the increasing dryness of surface
soil layers may have required crop moisture withdrawal from deeper soil
layers deficient in essential nutrients and thereby imposing nutrient stress. 11
is likely that both effects would occur simultaneously and the net result is a