Abstract
Effects of sowing time and planting density on the protein content of the seeds collected from main stems and branches were investigated to establish the cultivation technique for improving the protein content of soybean seeds grown in upland fields under paddy-upland rotation. In both main stems and branches, the protein content of the seeds was increased by late sowing and higher sowing density. Seeds on the main stem also had a irrespective of higher protein content than those on branches irrespective of sowing time and sowing density. The average protein content of seeds was negatively and significantly correlated with the number of branches per plant and cumulative temperature during the ripening period (CTRP). The correlation of the protein content with the branch number per plant was higher than that with CTRP, suggesting that the protein content of the seeds was more influenced by the branch number than CTRP. In addition, the protein content of the seeds was more affected by sowing time than sowing density in both main stems and branches.
