紫云英营养特性、栽培要点和肥效

本文是在国际紫云英学术讨论会上简介的内容。用同位素~(15)N试验表明:紫云英对氮肥的回收率,返青后施用的为71.1％,高于冬前施用的32.1％;植株的养分和吸收的标记氮肥约3/5分布在茎叶中;dff值表明,在花序、顶心、绿叶生理功能旺盛器官,比茎干和衰老器官低,说明生物固氮或土壤供氮对紫云英功能器官发育的重要性。植株N/P_2O_5比值表明,紫云英对于磷肥的反应不敏感。紫云英北移后的生态环境不同于南方,栽培技术要点归纳为接菌、早播、密植、灌水和施肥。配合施用磷肥能有效地提高绿肥肥效,使每公斤绿肥氮增产稻谷从5.2公斤提高到11.2公斤。

A STUDY OF THE NUTRITIONAL CHARACTER AND ITS GREEN MANURE VALUE OF ASTRAGALUS SINICUS

Using ~(15)N isotope tracing technique, the nitrogen absorption of Astragalus sinicus and its distribution in the plant were studied. The results indicated that the rate of recovery of the nitrogen applied was different at each growth stage. The amount of labelled nitrogen taken by the plant from the nitrogen fertilizer applied in spring was much higher than that applied in early winter (71.1%:32.1%), and 3/5 of the total amount absorbed was distributed in stem and leaves. The low dff value in physiologically active organs, such as young leaves, flowers, and stem apices indicated that the nodular nitrogen fixation and the application of nitrogen fertilizer were important for their development. The ratio of nitrogen and phosphorus in plant showed that Astragalus sinicus can use soil phosphorus, so it was not very sensitive to phosphorus fertilizer. In the northward extension of Astragalus cultivation, inoculation with suitable rhizobium, earlyand dense sowing, irrigation and application of fertilizer were necessary practices. Its green manure value could be increased by incorporation with phosphorus fertilizer. An increase of 6 kg of rice yield per kg of green manure nitrogen applied was obtained.