Abstract:
The objective of the present field experiment was to examine how plant density and enhanced
source, i.e. thinning treatments, may affect grain yield and its components for a
non-prolific maize hybrid, SC704. The environment of the hybrid maize crop was
changed at intervals over its life cycle by removing every other plant in rows equispaced
at 75 cm apart with a population of 13.34 plants m-2. The plants were grown with no water
or nutrient restrictions. Results showed that earlier thinning was associated with
greater stem, leaf, shoot and ear dry weight accumulation, ear kernel weight (EKW) and
kernel number per ear row (KNER). In this ways the greatest of these characteristics
were obtained in thinning at sowing i.e. 6.67 plants m-2 throughout. Delay in thinning until
the 12-leaf stage reduced stem dry weight and EKW significantly. Thinning at tasseling
also resulted in significantly lower stem dry weight accumulation compared to thinning at
sowing. At final harvest, the stem dry weight of plants thinned at tasseling was 20.47%
(P<0.05) lower than those thinned at sowing. Similar effects were found upon delay in
thinning until tasseling on leaf, shoot, and ear dry weight accumulation. Delay in thinning
until the 12-leaf stage or later, also reduced EKW significantly compared to plants
thinned at sowing. This reduction was attributable to decreased KNER and 1000-kernel
weight. According to these results, KNER and 1000-KW were found to be yield components
sensitive to light environment.
