Effect of Planting Densities on the Composition of Tillers in Rice Plant

[摘要] In rice culture, the planting densities are determined by two factors, viz., the number of seedlings per hill and that of hills per unit area (spacing). This experiment was conducted to investigate competition in composition of tillers under 15 different planting densities (Table 1). Two Varieties, Norin 6 (Panicle number type) and Norin 22 (panicle weight type) were used, and hills were arranged in square. On the number of tillers analysed according to their order (Fig. 1), 3rd tillers decrease at any plot under intense effect of competition, 2 nd tillers begin to decrease at the point of 3-4 seedlings per hill in spite of increase in seedlings per hill, and it corresponds nearly with the point of which 3 rd tillers decrease to zero. 1st tillers increase at each plot and may be so to a certain densities. As to the varietal differences both in competition of inter-hills and itra-hill, we may say as follows : panicle number type is more intensely effected at lower order tillers than panicle weight type, and vice versa at higher order tillers (Table 2, 3). Simultaneously emerged tillers showed the distinctive tendency (Fig. 2), viz., with the increase of seedings per hill and of hills per tsubo, the percentage of tillers which emerged in early stages increased. From the standpoint of composition of tillers, the increased number of seedlings per hill and of hills per tsubo are desirable so far as this experiment is concerned.

[学科分类] 农业科学（综合）