Studies on the empty husks (Shiina) in rice plant. : III. The effect of the phosphorous fertilizer on the occurrence of empty husks.

[摘要] In this experiment, phosphorous fertilizer was supplied as shown in table 1 to examine the influence of phosphorus on the occurrence of empty husks in rice plants, and the results are summerized as follows: - (1) Generally speaking, when phosphorous fertilizer was supplied more and the manuring time was earlier, the heading time was earlier, the percentage of empty husks was less and number of matured grains per plant was more numerous. (2) When the phosphorous fertilizer was supplied no or a little in early stage of growth then was complemented until early August, number of matured grains per plant increased on account of increase of culms and flowers. (3) When phosphorous fertilizer was supplied after middle August, number of matured grains per plant hardly increased but the function of flower became active at the flowering time or thereabout, and the percentage of empty husks became lower. In this case, if the plant was very want of phosphorus until this time, matured grains increased though the maturing time was obviously delaied, and if phosphorous fertilizer was supplied too much, the vital function of plant was disturbed and percentage of empty husks increased. (4) Under condition of restricted sunshine, empty husks increased in weaker frowers on panicle (formaly reported by auther), but under condition of restricted phosphorous supply, empty husks increased in vigorous flowers as well as in weaker flowers, therefore the decline of the function of flowers owing to phosphorous deficiency should seem to be more strong and fundamental. (5) In cotton flowers, the amount of daily absorption of phosphorus markedly increases after meiosis and fertilization. (Biddulph, 1945), and in rice plants, when they want of phosphorus at heading time or thereabout, phosphorus removes into kernels from leaves and stems then the concentration of phosphorus in leaves and stems decreases. From these facts, phosphorus seems to have influence upon the occurrence of empty husks in consequence of playing important part in the normal development of pollen and egg cell and in proceeding of fertilization. Nevertheless, increase of physiological activity of plant, increment of absorption of other nutrient elements, and the variation of concentration of various elements in plant tissue may be attendant on the phosphorous supply, and these may have influence more or less on the occurrence of empty husks. Therefor it is difficult to discuss in this experiment which will be more important factor of the occurrence of empty husks phosphorus itself or other various facts attendant on the phosphorous supply.

[学科分类] 农业科学（综合）