Analysis of Yield-Determining Process and Its Application to Yield-Prediction and Culture Improvement of Lowland Rice : LXIX. Studies on the principles for maximizing yield and their demonstration (2).

[摘要] In the previous paper (LXVII) the authors proposed the characteristics of the "ideal plant" and demonstrated through the "ideal plant" the possibility for obtatning 10.2 tons per hectare of brown rice, which was much higher than the yield of the first prize in the competition of maximizing yield in 1962 in Japan. In the present paper the authors furthermore tried to improve the method along the same line as shown in the previous paper, adding two other varieties, a narrower spacing, an earlier and a later planting treatment. Unfortunately, in 1963 the weather condition in the tillering stage was much worse than usual and it caused the plant to emerge less tillers and longer leaf-blades than those in 1962, in other words it made the plant grow somewhat in opposition to the characteristics of the "ideal plant". And, to make the matter worse, the weather condition in the ripening stage was also much worse than usual, so the percentage of ripened grains was much reduced by it. As a result of it, the yields of brown rice in 1963 ranged from 5.2 tons to 7.5 tons per hectare. A noteworthy fact, however, was observed in this experiment, i. e., the treatment No. 7 which was transplanted at the end of June obtained as much as 7.5 tons per hectare in yield of brown rice. (In general in Japan the rice plants transplanted at the end of June is less by 20 to 40% in yield than those transplanted in early May. And in 1963 the weather condition at the ripening stage of the latest transplanted treatment was a little bit better than those in earlier transplanted treatments.) This fact was considered to reconfirm the truth of the principle for maximizing yield by controlling the growth of plants aiming at the "ideal plant".

[学科分类] 农业科学（综合）