小麦/玉米间作优势及地上部与地下部因素的相对贡献

 明确种间地上部相互作用和地下部相互作用对间作优势的贡献，优化资源配置对提高间作体系产量具有重要意义。该文采用田间微区试验以及地下部种间根系分隔技术研究了玉米(Zea mays)覆膜与不覆膜两种情况下小麦(Triticum aestivum)/玉米间作优势及地上部和地下部因素对间作优势的相对贡献, 以期为间作体系的增产提供理论依据。结果得出，玉米不覆膜时小麦/玉米间作具有明显的产量间作优势(籽粒产量和生物学产量土地当量比(Land equivalent ration, LER)分别为 1.30和1 .29)，玉米覆膜能显著增加小麦/玉米间作系统产量间作优势（LER分别为1.41和1.40）；玉米不覆膜时小麦/玉米间作系统具有明显的氮、磷、钾养分吸收优势，玉米覆膜也能显著增加小麦/玉米间作系统养分吸收优势。小麦/玉米间作系统籽粒产量和生物产量间作优势来自地上部种间相互作用和地下部种间相互作用两个方面，但其相对贡献以地上部大于地下部， 当玉米不覆膜时均以地上部占75%、地下部占25%，当玉米覆膜时均为地上部占67%、地下部占33%，玉米覆膜能明显增加小麦/玉米间作系统产量间作优势地下部的相对贡献。地上部和地下部因素对小麦/玉米间作系统养分吸收优势也都具有重要贡献。玉米不覆膜时地上部和地下部因素对氮、磷养分吸收优势的相对贡献均分别为67%与33%，钾则相等（各占50%）；玉米覆膜能显著增加小麦/玉米间作系统氮、磷养分吸收优势地下部贡献率，但对钾养分吸收优势贡献影响不明显。表明,间作优势不仅可以通过作物组合来获得，也可通过地膜覆盖等措施进行调控，玉米覆膜能显著增加小麦/玉米间作系统产量间作优势和养分吸收优势及其地下部的相对贡献。可见，该研究对小麦／玉米间作模式持续增产和发展具有十分重要的指导作用。

INTERCROPPING ADVANTAGE AND CONTRIBUTION OF ABOVE- AND BELOW-GROUND INTERACTIONS IN WHEAT-MAIZE INTERCROPPING

Aims Optimization of resource structure is important for improving the yield of intercropping systems. Our objective was to clarify the contribution of above- and below-ground interactions to the intercropping advantage.  Methods We employed a micro-plot experiment and root barriers in a wheat-maize intercropping system with or without maize plastic sheet mulching. Important findings Non-plastic sheet mulching wheat-maize intercropping system has a yield advantage with land equivalent ratios (LERs) for grain yield and biomass of 1.30 and 1.29, respectively. Plastic sheet mulching with maize can significantly increase the yield advantage of intercropping, with LERs for grain yield and biomass of 1.41 and 1.40, respectively. There is increased nitrogen, phosphorous and potassium uptake in the non-plastic sheet mulching wheat-maize intercropping and with plastic sheet mulching with maize. In the non-plastic sheet mulching intercropping system, the relative contribution to the intercropping advantage is 75% above-ground and 25% below-ground, but in the plastic sheet mulching intercropping system it is 67% above-ground and 33% below-ground. The relative contribution of above-and below-ground interactions to nutrient advantage are 67% and 33% for nitrogen and phosphorus and 50% and 50% for potassium, respectively, in non-plastic sheet mulching intercropping; however, plastic sheet mulching with maize can increase the below-ground contribution to nitrogen and phosphorus advantage in the intercropping (there is no significant influence to potassium advantage). Intercropping advantage can be obtained by crop matching and controlled by plastic sheet mulching. Plastic sheet mulching with maize can significantly increase yield advantage, nutrients absorption advantage and the below-ground contribution.