小麦玉米同步增密有利于优化种间关系而提高间作产量

Synchronously higher planting density can increase yield via optimizing inter-specific interaction of intercropped wheat and maize

增密是间作高产的主要措施,研究间作组分密度变化对其种间关系、产量的影响,对于夯实间作理论与技术意义重大。2018-2019年,在河西绿洲灌区开展田间试验,设单作玉米、单作小麦、小麦/玉米3种种植模式,4.5万株hm^(-2)(传统)、6.0万株hm^(-2)(中)、7.5万株hm^(-2)(高)3种玉米密度,284万粒hm^(-2)(传统)、341万粒hm^(-2)(高)两种小麦密度,研究了小麦玉米同步增密对间作种间关系及产量的影响。结果表明,间作小麦、玉米密度同步增大强化了共生期小麦相对于玉米的竞争力(A_(wm)),小麦高密度间作与传统密度间作相比,A_(wm)提高了10.9%~20.1%;玉米高、中密度间作与传统玉米密度间作相比,其A_(wm)分别提高了25.3%~32.0%、15.8%~17.3%;小麦、玉米高密度间作与传统密度间作相比,A_(wm)提高了35.5%~56.5%。间作小麦、玉米密度同步提高可增大麦后间作玉米的恢复效应(Rm),小麦高密度间作较传统密度间作的Rm提高了14.6%~17.1%;玉米高、中密度间作与传统密度间作相比,Rm分别提高了27.4%~48.5%、10.3%~30.5%;小麦高密/玉米高密度较小麦/玉米传统密度处理Rm提高了43.7%~65.5%。增密有利于提高间作优势,小麦高密/玉米高密度较小麦/玉米传统密度处理土地当量比高8.3%~10.8%。两作物同步增密可进一步提高间作增产优势,小麦高密度间作较传统密度间作增产3.6%~5.1%,玉米高、中密度间作较传统密度间作增产14.1%~19.3%、7.3%~15.2%,小麦高密/玉米高密度较小麦/玉米传统密度处理增产19.0%~24.0%。间作小麦对玉米的竞争力及麦后玉米的恢复效应与间作籽粒产量均呈正相关。小麦玉米同步增密可优化间作种间关系、提高产量,小麦播种量341万粒hm^(-2)和玉米7.5万株hm^(-2)是绿洲灌区小麦间作玉米高产的适宜密度。

Increasing planting density is the main measure for high yield in intercropping.It is of great significance for the theory and technology of enhancing intercropping system to investigate the effects of intercrop’s density changes on the interspecific interaction and yield.In 2018 and 2019,a field experiment was carried out in Hexi oasis irrigation area,with three cropping pat-terns of monocropping maize,monocropping wheat,wheat-maize intercropping,and three maize densities of 45,000 plants hm^(-2)(traditional),60,000 plants hm^(-2)(medium),75,000 plants hm^(-2)(high),and two wheat densities of 2.84 million grains hm^(-2)(tradi-tional)and 3.41 million grains hm^(-2)(high).The effect of synchronously higher planting densities of wheat and maize on in-ter-specific relationship and yield of intercropping system was studied.The results showed that the densities of intercropped wheat and maize were increased simultaneously,which strengthened the competitiveness of wheat relative to maize(A_(wm))during the co-growth period.For the intercropped wheat,compared to traditional planting density,high density increased the A_(wm)by 10.9%-20.1%.For the intercropping maize,compared to traditional planting density,high density and medium density improved the A_(wm)by 25.3%-32.0%and 15.8%-17.3%,respectively.In addition,compared to intercropped wheat and maize with traditional density,synchronously higher planting density for intercropped wheat and maize increased the A_(wm)by 35.5%-56.5%.The simul-taneous increase of the density of intercropped wheat and maize could increase the recovery growth effect of intercropped maize(Rm)after the intercropped wheat harvested.For the intercropped wheat,compared to traditional planting density,high density increased the Rm by 14.6%-17.1%.For the intercropping maize,compared to traditional planting density,high density and me-dium density improved Rm by 27.4%-48.5%and 10.3%-30.5%,respectively.In addition,compared to intercropped wheat and maize with traditional density,synchronously higher planting density for intercropped wheat and maize increased Rm by 43.7%-65.5%.Increasing planting density was conducive to improve the advantage of intercropping.The land equivalent ratio of high-density for both intercropped wheat and maize was 8.3%-10.8%higher than that of intercropped wheat and maize with tra-ditional density.The simultaneous increase in the density of intercropped wheat and maize could further improve the advantage of intercropping.For the intercropped wheat,compared to traditional planting density,high density increased the grain yield of inter-cropping system by 3.6%-5.1%.For the intercropping maize,compared to traditional planting density,high density and medium density improved grain yield of intercropping system by 14.1%-19.3%and 7.3%-15.2%,respectively.Synchronously higher planting density for intercropped wheat and maize had greater grain yield of intercropping system by 19.0%-24.0%than that of intercropped wheat and maize with traditional density.A positive relationship was observed between total grain yield of intercrop-ping system and the competitiveness of wheat relative to maize and the recovery growth of intercropped maize after intercropped wheat harvest.In conclusion,synchronously higher planting density could increase grain yield via optimizing interspecific inter-action of intercropped wheat and maize.Our results revealed that 4.5 million grains hm^(-2)of wheat and 75,000 plants hm^(-2)of maize were the suitable planting densities for high yield of wheat and maize in intercropping system in oasis irrigation area.