间套作系统作物和土壤碳氮磷化学计量时间动态特征及调控机制

Intercropping has been widely practiced in China, researchers concern how recent knowledge from agronomy, plant physiology and ecology can be combined with the aim of improving intercropping systems. Plant and soil carbon: nitrogen: phosphorus stiochiometry provides a new idea to address this topic. However, recent stoichiometry studies were mainly conducted in natural ecosystems, with little attention been paid to agricultural ecosystems. This project will take the widely practiced wheat/maize and maize/faba been intercropping ecosystem as examples, crops and soils will be sampled every two weeks and their C, N, P concentration will be measured in the field and greenhouse experiments, the first aim is to investigate the dynamics of crop and soil C:N:P stiochiometry; the second aim is to explore the role of crop traits (e.g. species variation and growth rate), interspecific interactions (competition and facilitation) and fertilization (N or P addition) in determining the dynamics of crop and soil C:N:P stiochiometry. This study will expand the theoretical framework of C:N:P stiochiometry, increase our understanding of nutrient uptake and recycle in intercropping. In addition, this project will have implications for improving nutrient uptake and yield advantage in intercropping systems.

间套作在我国农业生产上占有重要地位，近年来，研究者关注如何结合农学、植物生理学和生态学的知识来充分发掘间套作的潜力，植物与土壤化学计量研究为解决这一问题提供了新的思路。然而，目前生态化学计量的研究主要集中在自然生态系统，对间套作等农田生态系统化学计量特征的认识十分有限，对其控制因素的认识更是缺乏。本项目以农业生产中广泛应用的小麦/玉米和玉米/蚕豆间套作生态系统为例，结合大田和室内控制试验，通过对作物和土壤每2周采样并测定C、N、P含量，研究作物和土壤C:N:P化学计量时间动态特征，同时探讨作物自身属性(如物种差异、生长速率等)、种间相互作用(竞争和互惠)和施肥措施(N肥和P肥添加)对作物和土壤C:N:P化学计量时间动态特征的调控。研究将完善化学计量学理论框架，增进对间套作系统养分利用和养分循环过程的理解，为充分挖掘间套作系统养分吸收和产量优势提供科学依据。

间套作在我国农业生产上占有重要地位，化学计量研究可为发掘间套作潜力提供新的思路。然而，目前生态化学计量的研究主要集中在自然生态系统，对间套作等农田生态系统化学计量特征及其控制因素的认识有限。本项目以小麦/玉米和大麦/玉米间套作生态系统为例，通过对作物每2周采样并测定N、P含量，研究作物N:P化学计量时间动态特征及其控制因素。结果显示（1）间作体系小麦和大麦的最大氮吸收值要显著高于相应单作，间作玉米养分吸收早期受种间竞争的抑制，但在大、小麦收获后迅速恢复，间作玉米最大氮吸收值要显著高于相应单作。间作体系不同作物之间最大养分吸收速率时间显著分隔开来。（2）在生长初期，大部分N、P被分配给生长功能，N：P在所有处理和物种中都与生长速率(GR)呈负相关，与生长速率假说(GRH)预测一致。在生长后期，随着种子的形成，N、P分配给生长功能的比例逐渐降低，GR逐渐降低，N：P与GR关系与GRH预测不完全一致。（3）间作对三种作物N:P比无显著影响。氮肥对这些作物N:P比的影响不一致，覆膜显著降低玉米N:P比。研究将完善化学计量学理论框架，增进对间套作系统养分利用和养分循环过程的理解，为充分挖掘间套作系统养分吸收和产量优势提供科学依据。