Studies on the Growth of Rice Plants Cultivated in Different Seasons : V. Dependence on fertilizer of the rice plants cultivated in different seasons.

[摘要] Field experiments were conducted to find out the fertilizer response and dependence on fertilizer of rice plants cultivated in different seasons from 1957 to 1960. Three different seasonal rice cultures were tested, namely, the first, early seasonal culture (transplanted in May and harvested in August or September), the second, ordinary seasonal culture (transplanted in June and harvested in October) and the third, late seasonal culture (transplanted in July and harvested in late October). Norin No.17 was applied in the first, Miho-nishiki was applied in the second, Kogane-nishiki was applied in the third and also Norin No. 29 was tested in each seasonal culture. The results obtained are as follows: 1. Early seasonal culture increased in the number of tillers and panicles per unit area as compared with the other two seasonal cultures both in fertilized and non-fertilized plots. However, the superiority of number of tillers and panicles was not remarkable in the non-fertilized plot. This can be attributed to less appearance of soil fertility due to the lower temperature during the tillering stage. 2. The rice yield increased in proportion to the earliness of transplantation, particularly in case of Norin No. 29. The rate of difference in rice yield between fertilized and non-fertilized plots was the highest in early transplanted plot. In case of the late seasonal culture, about 90 % of the yield was produced even in the non-fertilized plot as compared with the fertilized one. On the contrary, in the heavy fertilized plot, the highest yield was produced in the early seasonal culture. The yield in the ordinary culture showed the intermediate tendency. It was then concluded that the fetilizer response of the rice plants was higher in the early seasonal culture and dependence on soil fertility was higher in the late seasonal culture, as compared with the other two cultures, respectively. 3. Positive high correlations were found between the weight of rice straw and its yield and between number of panicles per unit area and yield in all plots. Effectiveness of increased number of panicles on yield was particularly higher in the early seasonal culture and its effectiveness was much strengthened by increased fertilizer. The high productivity of rice would be expected in the early seasonal culture under heavy fertilized plot.

[学科分类] 农业科学（综合）