Morpho-physiological variations and yield associated with planting density in soyabean(Glycine max.(L)merrill)

ABSTRACT
Understanding morpho-physiological factors associated with yield decline at high
density in soybean (Glycine max L.) can assist in optimizing productivity and seed
quality. The objective of this study was to determine effects of different spacing on
development and seed quality. The study tested the concept of yield plasticity. Five
varieties that included determinate (SC Safari, Dina and Magoye) and indeterminate
(Kaleya and Pan 1867) and three densities (300,000, 400,000 and 550,000 plants/ha)
were used. A randomized complete block design arranged in 2 factor- factorial with
variety and plant density and 4 replications was used. The experiment was done at
Seed Control and Certification Institute in Chilanga, Zambia in 2015. Parameters
assessed included: height, branches/plant, chlorophyll, nitrogen, 50 % flowering,
pod-fill time, maturity duration, biomass, seed quality, yield and yield components.
Significant effects for variety were present for all parameters while plant density
effects were highly significant for number of branches/plant (p < 0.001), biomass
yield (p < 0.001), pods/plant (p < 0.001), seeds/pod (p < 0.001) and yield (p ≤ 0.05).
Interaction effects were observed for pods/plant and seeds/plant. Traits positively
and significantly correlated to yield were height, canopy biomass yield, pods/plant
and seeds/plant. Biomass, pods/plant, seeds/plant and 100 seed weight contributed
significantly to total variation of grain yield at R2 = 85.3 %. Plant height, biomass
yield, number of pods/plant, number of seeds/plant and hundred seed weight were
critical parameters determining yield elasticity. Kaleya, Pan 1867 and Dina appear
more tolerant of planting at high density.