ON THE EFFECT OF THE OPENING TIME OF IRRIGATION ON THE GROWTH OF RICE PLANT. Report 2 (2)

[摘要] This experiment was carried out from May to October, 1949. At the 87 th meeting of the Crop Science Association, we reported the resume (Report 2)(no. 1) on the growth of root, which was a part of this experiment. This time we are going to report on the investigation about yields and growth. (1) In the pots filled up with water about 10 days beforehand of heading, in both direct sowing plots and transplanting plots, the growth of rice plant was retarded completely just like the one in the pots of upland field at the direct sowing plots. (2) The best time of the opening time of irrigation, in the direct sowing plots, is not clear as we found in old reports. In this experiment we could not find much difference on the growth of rice plant among three different irrigations, -the pots filled up with water on the first of July, the pots filled up from the beginning, and the pots on the 26 th of July. The rice plant obtained from the pots filled up with water on the 26 th of July, showed a little better than the others on their tops, leaf numbers, and tillers. This tendency might be attributable to the absorption of nutritive elements and their environments. (3) There were not a remarkable difference on the width and the length of the leaf among them, with the exception of the one from the pots of upland field. (4) Increasing rate of both tiller and top height was the greatest in ten days after filling up with water. (5) The most active time of tiller and the time when the top reach its highest, were delayed 2 or 3 days in case of the trans-planting plots compared with the one in the direct sowing plots. This delaying caused by transplanting is regarded as a physiological phenomenon and it seems to be out of any further discursion. (6) In comparing the direct sowing plots with the transplanting plots in the case of filling up water from the beginning, the weight of grains odtained from the former is superior 2.9% to the one from the latter, and more over when the former is filled up with water on the 1st of July it shows 2.6% more weight to the latter. On the other hand the weight of grains obtained from all other plots which we have not mentioned above are inferior to the one from transplanting plots filled up with water from the beginning. (7) As to the grain numbers of one head and head length, the direct sowing plots are inferior to the transplanting plots. And as to tiller the direct sowing plots are recorded to be superior to the transplanting plots. Thus it seems to us that they keep their balance on the whole in considering of their yields.

[学科分类] 农业科学（综合）