玉米大豆间作干物质积累和氮磷吸收利用的边际效应

Marginal effect of dry matter accumulation and nitrogen and phosphorus uptake and utilization in maize and soybean intercropping

【目的】研究间作对玉米大豆干物质积累及氮磷吸收利用特性的影响机制,对实现玉米、大豆间作高产高效具有重要指导意义。【方法】试验设玉米单作、大豆单作、玉米大豆间作3种种植方式,分别测定玉米大口期、吐丝期和成熟期的植株氮磷积累量和大豆开花期、结荚期和成熟期的植株氮磷积累量,研究间作对玉米、大豆不同器官干物质积累及氮磷吸收积累特性,明确氮磷吸收利用的边际效应。【结果】与单作相比,间作降低了玉米干物质和氮磷的积累,促进了根系吸收氮向籽粒的分配;降低了大豆干物质积累,尤其对中行的影响大于边行,边行干物质、氮磷积累体现边际效应优势;与单作体系相比,间作使玉米大豆植株茎叶营养器官氮转移量均减少,分别降低22.13%、29.85%,转运氮对玉米籽粒氮的贡献率分别下降5.11%、17.45%,且根系吸收氮对籽粒氮的贡献率均高于转运氮对籽粒氮的贡献率。间作能够有效提高系统氮利用效率,较玉米、大豆单作分别提高2.34%、4.62倍,使系统氮效率较单作大豆提高26.82%,较单作玉米降低10.16%,玉米在系统产量中占主导地位,占系统产量的82.27%,土地当量比(LER)达到1.47,系统产量为13110 kg/hm^(2),较单作玉米下降3.96%。【结论】间作优势主要在于促进根系吸收氮向籽粒的分配,提高氮的利用效率。

【Objective】The present paper aimes to study the effects of intercropping on dry matter accumulation,nitrogen and phosphorus absorption and utilization of maize and soybean,and to clarify the mechanism,which has important guiding significance for realizing high yield and high efficiency of maize and soybean intercropping.【Method】Three planting methods were set up in the experiment,namely,maize single cropping,soybean single cropping and maize and soybean intercropping.Nitrogen and phosphorus accumulation of maize plants at widemouth stage,spinnery stage and maturity stage,and nitrogen and phosphorus accumulation of soybean plants at flowering stage,pod stage and maturity stage were measured respectively.The characteristics of dry matter accumulation and nitrogen and phosphorus absorption accumulation of different organs of maize and soybean were studied by intercropping,and the marginal effects of nitrogen and phosphorus absorption and utilization were clarified.【Result】Intercropping decreased the accumulation of dry matter and nitrogen and phosphorus,and promoted the distribution of nitrogen from roots to grains compared with single cropping.The dry matter accumulation of soybean was reduced,especially the influence on the middle row was greater than that on the side row,and the dry matter and nitrogen and phosphorus accumulation on the side row showed marginal effect advantage.Compared with the mono-cropping system,intercropping reduced the nitrogen transfer amount of vegetative organs in stems and leaves of corn and soybean plants by 22.13%and 29.85%,respectively,and the contribution rate of transport nitrogen to corn kernel nitrogen decreased by 5.11%and 17.45%,respectively,and the contribution rate of root nitrogen absorption to grain nitrogen was higher than that of transport nitrogen to grain nitrogen.Intercropping could effectively improve the nitrogen use efficiency of the system,which was 2.34%and 4.62 times higher than that of corn and soybean monocropping,respectively.The nitrogen use efficiency of the system was 26.82%higher than that of soybean monocropping,and 10.16%lower than that of corn monocropping.Corn occupied the dominant position in the system yield,accounting for 82.27%of the system yield,and LER reached 1.47.The system yield was 13110 kg/hm^(2),which was 3.96%lower than that of monocroping maize.【Conclusion】The main advantage of intercropping is to promote the distribution of nitrogen absorbed by roots to grains and improve the efficiency of nitrogen use.