The Growth, Yield and Seed Quality in Broadcast Cultivation of Soybean Under the Low Density Seedling Establishment

In this study, we clarified the effects of low density seedling establishment in broadcast cultivation, which is a labor saving technique, on the growth, yield, and seed quality of soybean. In broadcast cultivation, the seedling establishment in the four corners of the plot (low density plot, LD) was about 35% of that further in the plot (average density plot, AD). In LD, the shoot dry weight was lower than that in AD until the flowering stage. Thereafter, the shoot dry weight of the soybean in LD increased with a sharp increase in leaf-area-index (LAI), and became similar to that of soybean in AD at the seed-filling stage. Although, the density of nodes (number of pods per m2) was lower in LD than in AD, the number of branches, number of branching nodes per plant, and number of pods per node were higher. Therefore, there were no significant differences between LD and AD in number of pods per m2 and yield. There was a positive correlation between the number of pods per node and increments in the values of LAI and SPAD-meter readings from the flowering stage through to the seed-filling stage. These results suggest that in broadcast cultivation the growth of branches in LD was promoted and the number of pods per node was increased due to vigorous leaf expansion, accompanied with leaf-color improvement from the flowering stage to the seed-filling stage.