Effect of Shade Treatment after the Beginning of Bloom Stage on Seed Production of Soybean Cultivar ‘Fukuyutaka’ and ‘Misato-zairai’ without Branching Vegetation

Abstract

Plants of soybean cultivars ‘Fukuyutaka’, a popular cultivar in western Japan, and ‘Misato-zairai’, a local soybean cultivar in Mie Prefecture, were shaded after the beginning of bloom stage. To examine light utilization in a simple sink-source relationship between pods and leaves only, shoot apices on the main stem, branches, and new lateral buds were removed during the treatment. In both cultivars, shading decreased seed weight and the numbers of pod and seed. Seed weight and pod number were positively correlated. Total air-dried weight at maturity (total weight, including stem, pods, and seeds) was also decreased by shading and was positively correlated with pod number. Shading had no reproducible effects on 100-seed weight. Light utilization of ‘Misato-zairai’ plants without branching vegetation was similar to that of ‘Fukuyutaka’.