氮磷配施对玉米-大豆套作模式下种间作用、玉米产量及干物质积累与转运的影响

以盆栽和田间小区试验结合的方法,通过设置根系分隔与不分隔方式及不同供氮(0、120、180、240kg/hm~2,记为N_0、N_(120)、N_(180)、N_(240))、供磷水平(0、35、70、105kg/hm2,记为P_0、P_(35)、P_(70)、P_(105)),探究在玉米-大豆套作模式下氮磷配施对种间作用、玉米产量及干物质积累与转运的影响。结果表明,1)氮磷互作效应对带状套作系统的种间促进作用显著,配施可缓解玉米与大豆的种间竞争作用,提高套作系统土地当量比率、种间竞争力和营养竞争比率,促进玉米对氮、磷素的吸收,表现出显著的套作产量优势和资源利用优势(LER1),且优势效应高于单施氮、磷肥。2)氮磷互作对玉米各生育期干物质积累量的影响呈峰形变化趋势,中氮中磷(N_(180)P_(70))处理可显著降低花前干物质的积累量,增加成熟期干物质积累总量,促进花后干物质积累向籽粒转运,提高玉米收获指数。3)种间作用和氮磷互作可显著影响玉米产量,提高套作玉米有效穗和穗粒数,两种植模式中无论施肥与否,在套作条件下玉米的产量均高于净作,且在N_(180)P_(70)处理时玉米产量达到最大值,套作较净作增产幅度达1.65%~20.43%。本研究结果表明,套作模式下玉米氮磷配施以施氮180kg/hm~2、施磷70kg/hm~2时,种间促进作用显著,可改善其穗部性状,有利于成熟期干物质的积累和向籽粒的转运,最终获得较高的产量。

Effects of combined applications of nitrogen and phosphorus on interspecies interaction,yield, and dry matter accumulation and translocation in maize in a maize-soybean relay intercropping system

The aim of this study was to investigate the effect of nitrogen and phosphorus application on maize in a maize-soybean relay intercropping system.A pot experiment was conducted in 2013 and 2014,and interspecies interactions,dry matter production and accumulation,and grain yield were assessed.The experiment consisted of four nitrogen levels N0 (0),N120 (120 kg/ha),N180 (180 kg/ha),N240 (240 kg/ha)] and four phosphorus levels P0 (0),P35 (35 kg/ha),P70 (70 kg/ha),P105 (105 kg/ha)].Furthermore,to evaluate the root interaction between maize and soybean,the two plants were grown with or without a root barrier between them.The main findings were as follows:1) The interaction between N and P significantly affected the inter-specific interaction of maize and soybean in the relay intercropping system,reduced inter-specific competition between maize and soybean,increased the land equivalent ratio,increased the aggressiveness and nutrition competition ratio,and increased the uptake of N and P.The interaction between N and P significantly increased the yield and resource utilization (land equivalent ratio＞1).The interactive effect of N and P was more prominent than the effect of N or P alone in the intercropping system.2) The effects of the N×P interaction on dry matter accumulation in each growing period of maize increased with increasing N and P application rates up to N180 (180 kg/ha) and P70 (70 kg/ha),and then decreased when N and P application rates were N240 (240 kg/ha) and P105 (105 kg/ha).The treatment of N180 (180 kg/ha) and P70 (70 kg/ha) significantly decreased maize dry matter accumulation before maturity,but promoted dry matter accumulation and translocation to the grain,and improved the harvest index of maize.3) Inter-specific interactions and interactive effects of N and P were significant,and increased the yield by increasing the number of kernels per ear and the number of ears per maize plant.Among all the N and P fertilizer levels,N180(180 kg/ha) and P70 (70 kg/ha) considerably improved the maize yield from 1.650％ to 20.430％ in the relay intercropping system,compared with sole cropping.On the basis of these results,we recommend nitrogen and phosphorus applications at the rates of N180 (180 kg/ha) and P70(70 kg/ha) to substantially improve ear traits,increase dry matter translocation to the grain at maturity,and achieve the maximum yield of maize in a maize-soybean relay intercropping system.