| dc.description.abstract | Soybean has the ability to modify its growth characteristics in response to changes in plant
population and biotic stress. This study focussed on the effect of plant density and weeding on
the shoot and leaf traits in the Maksoy 3N variety, and its adaptive mechanisms in face of
competition for growth resources. A field experiment was set up at Makerere University
Research Institute Kabanyolo (MUARIK) to examine the growth variability in soybean by
plant density and weeding. The experiment was set up in a Randomized Complete Block design
with split-plot arrangement with density in the main plots and weeding in the subplots. Soybean
variety Maksoy 3N was planted at 400,000 (S); 500,000 (H1); 666,667 (H2); 1,000,000 (H3);
333,333 (L1); and 285,714 (L2) plants ha-1 interacted with two levels of weeding (Weeded and
Not weeded). Data collection was done for five weeks, starting at one week after germination
on parameters including, dry matter of leaves, dry matter of shoots, plant height, number of
leaves and trifoliates, and leaf area. Soybean plants at low densities (i.e., below 500,000 plants
ha-1) accumulated more dry matter than at high densities (i.e., above 400,000 plants ha-1). Dry
matter accumulation was generally more in weeded plots than in unweeded plots across all
densities even at high densities. Soybean plants at high densities (i.e., above 500,000 plants ha-
1) were taller than those at low densities (i.e., below 400,000 plants ha-1). However, in
unweeded plots, plants were generally taller than those in weeded plots across all densities.
Leaf area of soybean plants was generally larger at high densities (i.e., above 400,000 plants
ha-1) than at low densities (i.e., below 500,000 plants ha-1). However, plants in weeded plots
had larger leaf area compared to those in unweeded plots. Furthermore, Maksoy 3N employs
adaptive mechanisms like, increasing number of leaves, leaf area, and plant height to enhance
light interception, particularly at high plant densities, to facilitate carbon-dioxide metabolism,
and in turn promote dry matter accumulation in leaves and shoots. However, in presence of
weeds, the efficiency and effectiveness of some of these mechanisms is weakened. Therefore,
the findings from this research showed that limiting Maksoy 3N density to 400,000 plants ha-1
ensures that plants have an adequate amount of land area to extract the necessary growth
resources efficiently, and it also allows plants to compete favorably in face of interspecific
competition from weeds.
Keywords: Adaptive growth response, Biotic stress, Glycine max, Planting density, Uganda | en_US |
