Abstract
We examined the effects of the occurrence of damaged seeds on the number of seeds per pod and seed yield of soybean sown in June (June plot) and July (July plot) in Kanagawa Prefecture, Japan. Field experiments were conducted at the experimental farm of the College of Bioresource Sciences, Nihon University (Fujisawa City, Kanagawa Prefecture) in 2018 and 2021. The cultivars used in this experiment were ‘Satonohohoemi’, ‘Enrei’, and ‘Tachinagaha’ in 2018 and ‘Enrei’ in 2021. The above-ground growth at the beginning of the seed filling stage was more vigorous in June plots than in July plots in both years and all cultivars. However, the percentage of putrefied seeds at the maturity stage was higher in the June plot than in the July plot. The number of seeds per pod and the number of pods per node in the June plot were lower than those in the July plot, and there was no difference in seed yield among the plots. Moreover, the temperature during the seed filling stage in the June plot was higher than that in the July plot, and the field condition in the June plot was more susceptible to pathogen occurrence. From the above results, there was no difference in seed yield between the June and July plots in Kanagawa Prefecture. Moreover, it will be possible to decrease the amount of pesticide applied by delaying the date of sowing to July sowing in Kanagawa Prefecture.
