Plant Growth Regulating Action of Brassinolide : I. The effect of brassinolide on the ripening of rice plants under the low temperature condition

[摘要] The effect of brassinolide [ (2-alpha, 3-alpha, 22R, 23R) -tetrahydroxy-24S-methyl-B-homo-7-oxa-5-alpha-cholestan-6-one] on the ripening of rice plants under the low temperature condition was investigated. In 1985, the rice plants were transfered to a growth chamber and kept under natural day-light. The low temperature condition was set up at 22/ 17°C (day/night) for 15 days which was at early stage of ripening after heading. The foliar application with brassinolide of 1 ppm and O.O1 ppm concentration at spikelet differentiation stage, meiosis stage and heading time gave 61%, 77% and 75% ratios, on an average, of ripened grains respectively, while in control it was 57.5%. In each of the brassinolide treatments, the increasing pace of the grain weight from the early stage of the ripening till the middle stage became faster than that in the untreated control. In 1987 and 1988, the effect of brassinolide on the ripening of rice plants, set up by late seeding and late transplanting Nissan Chemical Industries, LTD., was investigated under the condition of the low temperature in natural paddy field. O.O1 ppm brassinolide was sprayed by each 2 times at the combinations of spikelet differentiation stage and meiosis stage, meiosis stage and heading time, and spikelet differentiation stage and heading time. The speed of ripening was promoted and the percentage of ripened grains was also increased. From these results, it was observed that brassinolide increased ripening under the low temperature condition of this experiment in the ripening period.

[学科分类] 农业科学（综合）

[关键词] Rice ( Oryza sativa L.);イネ(Oryza sativa L.);Spikelet differentiation stage;穎花分化期;Meiosis stage;減数分裂期;Heading time;出穂期;Ripening;登熟;Brassinolide;ブラシノライド;Grain weight