Studies on the Cool Injury in Bean Plants : I. Effect of nitrogen under low temperature on the pod setting and fertility of soybeans

[摘要] The effects of nitrogen supply under low temperature on the pod setting and fertility of the soybean plants were studied with the solution culture method. The low temperature treatment were kept at 15°C for 30 days under three different stages around flowering time. The variation in pod number under the low temperature treatments ranged widely with nitrogen (N) supply conditions. High N application during the low temperature treatments caused a remark able decrease in pod number, comparing with a 23°C condition. On the contrary, low N application during the low temperature treatments showed little decrease in pod number in the same comparison. The effects of the low temperature treatments around flowering time on the pod setting rate and fertility per cent were checked with flowers grouped, in relation to their flowering date, in four classes. High N application during the low temperature treatments considerably decreased the pod setting rate of flowers and the fertility per cent of pods in the sensitive stage, indicated l0 or 15 days before flowering till flowering, under low temperature. On the other hand, in the case of low N application, little significant direct damage was observed, under the same treatments, but some indirect damage symptoms such as the decrease in the number of flowers and flower number per node or small sized plants were remarked under the low temperature treatment in the mid - bloom stage on the main stem. The flowers escaped from the effects of low temperature, and flowers on the plants grown in the 23°C plots, showed high pod setting rate, with high N application within both nodulating and non-nodulating strains. Furthermore, the plants grown under the high N conditions had a prolongation of the flowering period and an increase in the number of flowers. These facts indicate that the high N conditions were favorable for obtaining a greater number of pods, except for the flowering stage affected by the low temperature treatments.

[学科分类] 农业科学（综合）