Studies on Cool Injury in Bean Plants : IV. Effects of nitrogenous fertilizers on the growth and yield of soybeans as subjected to low temperature from early to mid-reproductive stage

[摘要] 1) Experiment-I was conducted to examine the effects of a high level of nitrogen (N) application with several fertilizers, including slowly available N as a farmyard manure, rape seed cake, fish meal, IB and CDU on the growth and yield of soybeans subjected to low temperature, at 15°C, day and night under the natural light condition of a glasshouse in the phytotron for 15 days (L-1) or 30 days (L-2), from a few days before the onset of the flowering of the controls grown in a glasshouse, similar to the natural condition. In addition to an indeterminate type of American variety which was mostly used, its isogenic line, genetically alike in characters other than inability of nodulation, was referred to measuring the effects of nitrogenous fertilizers on growth and yield. The results will be described with nodulating plants unless otherwise indicated. Based on the flowers developed under 15°C during the sensitive stages to low temperature and their corresponding controls, seed yield and yield components of each fertilizer plot were compared with the L-2 and control condition for measuring the direct effect of low temperature injury. The major sources of decrease in seed yield were the decrease in the pod number, or pod setting rate, and the fertile seed percentage, but the statistical difference among fertilizers was only obtained in the pod number, or the pod setting rate. The rate of damage caused by the low temperature treatment was least at the farmyard manure and greatest at the CDU plot. In the total seed weight produced through the flowering period, the farmyard manure plot was the highest in both the two low temperature treatments and the control. All of the other four slowly available N fertilizers tested were also superior to both the high and standard level of ammonium sulfate. The weights of leaves and stems at maturity were the highest at the farmyard manure plot and all of the fertilizers tested showed similar trend to the seed yield. The nonnodulating line markedly responded to N fertilization in growth and yield, but the trend of response to fertilizers was in contrast to that of the nodulating line. Compared with the high level of ammonium sulfate plots, the plots slowly available N including the farmyard manure produced about 30% less in dry matter weight. The excellence of the farmyard manure for growth and yield was only shown in the nodulated plants in which no significant depression of N fixation was observed through plant development in spite of the high rate of N contained 2) Experiment-II was conducted to confirm the results of experiment-I and to examine the effects of the application of humates or oat straw, combined with the nitrogenous fertilizers, on the plants, when subjected to low temperature for 15 days, from the onset of flowering (L-4), five days before (L-3), or after (L-5) the onset of flowering of the controls, grown under the natural condition. The variety used is a representative of the determinate type in Hokkaido. The farmyard manure again exhibited stable and high seed weight over three different stages of low temperature treatments and the control. The plot, combined with 80% of N from slowly available N as CDU and 20% from ammonium sulfate, with or without the addition of humate or oat straw, showed as significantly high as farmyard manure in the seed yield, compared with the plots of high and standard levels of ammonium sulfate. Despite the increase in the 100-seed weight, the addition of humate, and or oat straw indicated no increase in the seed weight because of the depression of vegetative growth and the tendency of decrease in the flower number. [the rest omitted]

[学科分类] 农业科学（综合）