植物功能性状调控棉田间套作体系间作优势的补偿和选择效应机制

Enhanced productivity by plant diversity is commonly assumed to be driven by complementarity (CE) and selection effects (SE) between species. However, CE and SE as well as its underlying mechanisms are not fully understood in agricultural intercropping systems. Based on previous studies and recent advances, the central hypothesis of this project is that plant functional traits can mediate CE and SE by driving changes in soil resource availability, and regulating interspecific competition and facilitation. To approach the hypotheses suggested above, a field experiment with cotton-based intercropping systems (wheat/cotton and peanut/cotton) and root separations (no barrier and plastic barrier) will be used to determine the contribution of interspecific below-ground interactions to yield and nutrient acquisitions, CE and SE in intercropping advantages, the responses of competition-facilitation and soil CN to plant functional traits including specific leaf area, leaf dry matter content, leaf CN, specific root length, root length density and seed mass, and its relationship with CE and SE. Thus, by these, the objective of this research is to elucidate the mechanisms that plant functional traits mediate CE and SE through interspecific interactions and resource availability. The results will not only reveal ecological mechanisms of high yield and high efficiency in intercropping systems, but also have practical applications for breeding specific cultivars with desired traits and selecting the optimum crop combination suited to intercropping.

物种间的补偿和选择效应是多样性增加生产力的潜在机制。然而，这一研究在间套作农田生态系统非常薄弱，对其调控机制的认识则更为缺乏。基于前期研究和国内外进展，提出植物功能性状驱动资源有效性变化，调控种间竞争和促进作用，进而影响补偿和选择效应的科学假设。本项目以小麦/棉花和花生/棉花间套作体系为研究对象，采用根系不分隔和塑料膜分隔，研究种间地下部相互作用对间套作体系生产力和养分吸收量的贡献、间作优势的补偿和选择效应、竞争-促进作用和土壤碳氮对植物功能性状（比叶面积、叶干物质含量、叶片碳氮、比根长、根长密度、根系碳氮和种子质量）的响应及与补偿和选择效应的关系，最终阐明植物功能性状通过影响种间相互作用和资源有效性调控补偿和选择效应的过程机制。研究结果不仅可以揭示间套作体系高产高效的生态学机制，还可以为特定功能性状的作物品种培育和作物间套作的优化设计提供理论依据和指导。

生物多样性增加生态系统生产力，生态学理论基础是物种间的补偿和选择效应。间套作是增加农田生物多样性的主要方式，具有生产力和养分吸收优势。但补偿和选择效应是否在间作优势的发挥中起着重要作用及调控机制还鲜见报道。本项目采用两因素随机区组试验，设置小麦/棉花、大蒜/棉花、花生/棉花、棉花单作、小麦单作、大蒜单作、花生单作7种种植制度；根系不分隔、尼龙网分隔及塑料膜分隔3种分隔方式。通过测定作物农艺性状、产量、生物量、植物养分和土壤养分含量等指标，探究不同间套作及分隔方式对生产力、养分吸收和土壤养分的影响，以及不同棉花间套作体系下选择与补偿效应对间套作优势的影响。主要结果为：（1）隔根处理下的不同作物与棉花间作的土地当量比(LER)大于1，说明棉花间套作体系均体现出间作优势，且在小麦/棉花套作和大蒜/棉花套作的体系中，小麦和大蒜对于棉花的资源竞争力大于0，小麦和大蒜在共生期内是优势种；花生相对于棉花的资源竞争力小于0，在花生/棉花间作体系中，棉花是优势种。（2）小麦/棉花和大蒜/棉花体系中补偿效应为正值，选择效应为负值，说明两种套作体系中间套作优势主要来源于正的补偿作用；花生/棉花体系中补偿效应为正值，选择效应为正值，说明间作优势来源于补偿和选择效应，此外，根系分隔降低了间套作体系产量的补偿效应，但增加了选择效应。（3）与单作棉相比，小麦/棉花、大蒜/棉花和花生/棉花的土壤有机质含量平均提高了6.3%；土壤全氮含量提高了8.7%。（4）种间相互作用指数与补偿效应之间存在着显著线性关系，当相互作用指数升高时，补偿效应随之增加。而土壤全氮含量与补偿效应呈负相关。相关研究结果揭示间套作体系高产高效的补偿和选择效应机制，为改善棉田土壤养分管理和提高系统生产力提供理论依据。