Growth Regulating Action of Isoprothiolane in Plants : III. The effect of isoprothiolane on the ripening of rice plant under the low temperature condition

[摘要] Investigations were made on the effect of isoprothiolane (diisopropyl-1, 3-dithiolan-2-ylidene malonate, IPT) on the ripening of rice (Oryza sativa L.) under the low temperature conditions. The similar experiment was repeated 4 times in rice cultivation season every year from 1984 to 1987. Two varieties were used: Nipponbare and Koshihikari. Twenty seeds were directly sown in 1/5, 000a plastic pot (except for 1984.) and grown in a greenhouse. At 9, 12 days before heading or at the heading time, IPT 12% granule (FUJI-ONE(R)) at 200∼800 g/a was applied to rice plants in the pot under a flooded condition. The plants were tansferred to a growth chamber and kept under natural or atrficial day-light at 20/13°C (day/night)to cause cool! weather damage to them. Their panicles were collected at regular intervals. Grains were weighted on each rachis-branch. In 1985, both transpiration rate and color in the flag leaf were measured at 4 weeks after heading. The experimental results accumulated in four experiments in four years show that IPT had a promotive effect on grain weight, particularly the inferior grain weight until about 3 weeks after heading under the low temperature condition. After 6 weeks heading however, its effect decreased. IPT also increased the transpiration rate of the leaf blade at 4 weeks after heading.

[学科分类] 农业科学（综合）

[关键词] Grain weight;IPT;Heading;イネ(Oryza sativa L.);枝梗別籾重;Low temperature;出穂;Rice (Oryza sativa L.);低温;Ripening;登熟;土壌処理