Physiological and Ecological Studies of Rice Seedlings. : I Relation between rooting activity and variation in chemical composition of rice seedlings grown under different sowing density. : II Relation between rooting activity and chemical composition of rice seedlings grown under differently fertilized conditions.

[摘要] I. Experiments were made on the rooting activity of rice seedlings grown in lowland nurseries of different sowing density, in 1956. Thinly sown seedlings attained greater height and larger top-weight, and developed more abundant roots, than thickly sown seedlings. Therefore, "aging" seemed to have progressed quicker in thickly sown seedlings. Chemical composition of the seedling shoots depended upon their rootage. Both total sugar and starch contents increased with the amount of root, which is in turn controlled by nitrogen content in the shoot. Thus, thinly sown seedlings retained juvelinity, and had high rooting ability as compared with that of upland nursery seedlings. II. Furhter experiments in 1957 were made using various fertilizers on characteristically young and aged seedlings. Best results were obtained by the seedlings grown with 2N fertilizer for 44 days. When nitrogen denominater in the ratio suger+starch/nitrogen of the content in seedling is abnormally high additional applications of straw ash, KC1 and (NH4)2SO4 tended to improve the conditions and there were produced abundant roots. Rooting activity of seedlings were intensified by increasing the sum of total sugar+starch+nitrogen compounds caused by straw ash and KC1 applications, and on the other hand, by increasing total nitrogen in seedlings by means of addition of (NH4)2SO4 fertilizer.

[学科分类] 农业科学（综合）