Studies on the Nutrition of Rice Plant with Reference to Helminthosporium Leaf Spot (Preliminary report) : XI Absorption and translocation of nutrients as influenced by soil moisture and air humidity

[摘要] To make clear the effect of soil moisture and air humidity on the absorption and translocation of nutrients, two experiments were carried out : in one experiment, plants were grown at various levels of soil moisture by sand culture method, and in another experiment, plants were grown under different air humidity during ripening period just after heading. The results obtained are as follows : : (1) Decrease in soil moisture retarded the absorption of SiO2 and P2O5, and increase in air humidity diminished the absorption of SiO2 and K2O. (2) It was inferred that both low soil moisture and high air humidity retarded the upward translocation of SiO2 and K2O within the plant through the decreased transpiration, causing the decrease in the ratio of SiO2 or K2O content of leaf blade to that of leaf sheath and also in the ratio of SiO2 or K2O content of leaf to that of stem and resulted in the decrease of SiO2 or K2O content of leaf blade. (3) The increased susceptibility to Helminthosporium leaf spot caused by low soil moisture and high air humidity was assumed to have an intimate relation with the low ratios of SiO2 and K2O to N in leaf blade tissue.

[学科分类] 农业科学（综合）