水稲の生育及び出穂に及ぼす高夜温の影響

抄録

1. To study the effects of high night temperature upon the growth and heading of rice plants the following experiment was done, in which the early var., Riku-u-132, and the late var., Norin-18, were used. On May 15 they were sown in nursery bed, and on May 23 transplanted to the Wagner's pot. The plants were adequately managed. The materials were treated in two greenhouses, the one being heated during night time to raise the temperature of average 7°C higher than the other, or the control. The treatments were made at the young seedling stage, elongating stage, tillering stage, and booting stage. At each stage they were carried into the warm-night greenhouse during 30 days. The other treatment was all through the whole life. 2. By the treatment at the youg seedling stage and elongating stage, the rate of appearance of new leaf was increased but the plant height was decreased. By the treatment at the tillering stage the number of tiller was decreased. They were shown in the both varieties. Generally the number of ear decreased when treated, and earlier the treatment cleare was that phenomenon. The time of heading did not differ between the whole life treatments and the control, but with regards to the treatments at various stages, the heading delayed. The dry weight of harvested plants decreased by the warm-night treatment and this was particularly clear in the variety Ri-ku-u-132. 3. From these results, it is recognized that high night temperature treatment has an inhibitory effects upon the rice plants at the seedling and the tillering stage. The authors suppose that the effects may be related to the consumption of nutrients in the plant and that the optimum night temperatures for the growth may differ bettween the late and early varieties.