紫云英与氮肥配施对早稻干物质生产及氮素吸收利用的影响

为综合评价紫云英与氮肥配施对早稻干物质生产及氮素吸收利用的影响,筛选紫云英等量翻压条件下,较适宜的施氮水平,以冬闲常规施氮150 kg(N)?hm~(-2)]处理为对照,在翻压紫云英22 500 kg·hm~(-2)条件下,设置90 kg(N)·hm~(-2)、120 kg(N)·hm~(-2)、150 kg(N)·hm~(-2)和180 kg(N)·hm~(-2) 4个施氮水平,研究紫云英和施氮量对早稻干物质生产及氮素吸收利用的影响。结果表明:紫云英与氮肥配施各处理的干物质积累量均高于对照,其中紫云英配施氮肥90 kg(N)·hm~(-2)和120 kg(N)·hm~(-2)的干物质积累量最多,分别达9.65 t?hm~(-2)和9.97 t?hm~(-2),比对照分别增加11.18%和14.86%。各处理在水稻播种—分蘖期及抽穗—灌浆期干物质积累量较大,占成熟期干物质量的19.26%~24.77%和45.23%~52.75%,这两个生育阶段是干物质主要积累时期。紫云英与氮肥配施各处理的氮素积累量均高于对照,增幅为6.95%~18.68%。氮素干物质生产效率和氮收获指数均以紫云英配施90 kg(N)·hm~(-2)处理最高,比其他处理分别增加3.94%~14.08%和6.65%~14.90%。紫云英配施氮肥有利于提高早稻的干物质积累量和氮素利用率,其中以紫云英配施氮肥90 kg(N)·hm~(-2)和120 kg(N)·hm~(-2)效果较优,可实现减氮增效目的,是较理想的施肥模式。

Effect of combined application of Chinese milk vetch and nitrogen fertilizer on nitrogen uptake, utilization and dry matter accumulation in early rice

This study evaluated the effect of combined application of Chinese milk vetch (Astragalus sinicus L.) and different levels of nitrogen (N) fertilizer on dry matter accumulation and N use efficiency of early rice in order to determinate the suitable N level under application of Chinese milk vetch. Field treatments were set with four N application levels (90 kg·hm^-2, 120 kg·hm^-2, 150 kg·hm^-2 and 180 kg·hm^-2) under 22 500 kg·hm^-2 Chinese milk vetch using the winter fallow field with general N fertilizer level (150 kg·hm^-2) as the control. In the experiment, Chinese milk vetch was planted in winter and incorporated into soil in spring before early rice transplant, while N fertilizer was applied as base fertilizer, tillering fertilizer and heading fertilizer with 5:3:2 rate. The rice plants were sampled at tillering, booting, heading, filling and maturity stages of the early rice. Dry matter weight and N content were assayed, and the relative indexes were calculated. The results showed that all N application treatments had higher dry matter accumulation than the control. Specifically, the treatments with Chinese milk vetch combined with 90 kg(N)·hm^-2 and 120 kg(N)·hm^-2 increased dry matter (9.65 t·hm^-2 and 9.97 t·hm^-2) respectively by 11.18% and 14.86% compared to the control. Dry matter accumulation increased with duration of growth and peaked twice, one at sowing-tillering stage (19.26%-24.77%) and the other at heading-filling stage (45.23%-52.75%). The combined application of Chinese milk vetch and N fertilizer supported N integration that was beneficial to rice growth. The amounts of N accumulation of early rice treated with Chinese milk vetch and N fertilizer were higher than the control, with increases of 6.95%-18.68%. Among the treatments, that of Chinese milk vetch combined with 90 kg(N)·hm^-2 had the highest production efficiency of dry matter and N harvest index, with respective increases of 3.94%-14.08% and 6.65%-14.90% over other treatments. The results indicated that combined application of Chinese milk vetch with 90 kg(N)·hm^-2 or 120 kg(N)·hm^-2 was satisfactory because they reduced N fertilizer and increased N use efficiency at the same time, which was the ideal fertilization model for the study area.