Studies on the Nutrition of Rice with Reference to Helminthosporium Disease (preminary report) : II. The Nutrients Absorptionof Rice as Affected by the Hydrogen Sulphide Added to Culture Solution.

[摘要] In the previous work the increse of the susceptibility of rice to Helminthosporium disease caused by hydrogen sulphide added to culture solution was assumed to be referred to the retardation activity of roots for some nutrients due to the root injury by hydrogen sulphide. Then, in order to ascertain more exactly such an unfavorable effect of hydrogen sulphide on nutrients absorption, a solution culture experiment has been carried out, in which nutrients uptake by rice growing with or without hydrogen sulphide is examined. In this experiment the absorption rate as expressed by the quantities of nutrients absorbed per unit dry weight of a plant during a definite interval, was calculated by the analysis of the culture solution, and also the percentage cotents of each nutrient in stems and leaves of adult plant were determined. The results of the experiment are summarized as follows:-- (1) The absorption of some nutrients as well as water was considerably decreased by the addition of hydrogen sulphide to culture solution. Especially the absorption of potassium and silica was remarkablly inhibited. The uptake inhibition of nutrients and water was in the order K2O>SiO2>NH3-N>MnO>H2O>CaO. While the uptake of phosphorus was not retarded at all. (2) percentage contents of silica, potassium, manganese and calcium in stems san leaves were decreased by the addition of hydrogen sulphide. (3) The ratio of silica to nitrogen (SiO2/N) and that of potassium to nitrogen (K2O/N) which were appreciated to heve close relationship to the susceptibility were determined based on the amount of these nutrients absorbed during a definite interval or also on the percentage bontents of these nutrients in leaves and stens. And it was found that these ratios were considerably diminished by the addition of hydrogen sulphide. (4) From the analytical data of leaves and stems it is suggested that the translocation of calcium and phosphorus may be inhibited by the addition of hydrogen sulphide. (5) From these facts ahd other experimental results already reported, the increase of the susceptibility of rice to the disease which is due to hydrogen sulphide seems to be mainly attributed to the retardation of absorption of some nutrients, especially of potassium, silica and manganese.

[学科分类] 农业科学（综合）