Studies on the utilization of water by rice plant and the net duty of irrigationwater in the paddy field. (2)

Authors measured the absorption of water by the paddy rice, water content and dry matter of the paddy rice and the evaporation from the irrigated paddy field, in each growing period, 1954. These results are shown in Fig. 1-2 and Table 1-8.Air temperatures in June and July indicated the minimum records, and so the growing of the paddy rites were very slow. Therefore the absorption were few at first. The maximum absorption appeared from 25 days before the heading, the glume-primordial differentiation stage, to the heading similarly in 1953.The water requirements of the rice plants were from 230 to 305. The evaporation from the paddy field showed the similar values in the observation field till early in July and, had been decreasing with the growing of rice plants. The net duty of water in the paddy field (absorption+evaporation) showed the maximum in the latter half of August, 350-510lit/are/day.