间作响应密植的地上部生理生态机制研究

Compact planting is the fundamental practice for improving yield of crops, however, there lack of academic basis about above-ground eco-physiological responses of intercropped crops to high planting density, and also the correlations between compact planting and density-tolerant property. The theory for yield improvement of intercropping through plant density increasing is still scarce. Therefore, typical cereal-cereal and cereal-legume intercropping models are employed in this project under different combinations of plant densities, strip ratios, crop breeds, and fertilization rates. The objectives of this research are to: (1) determine the dynamic of various indicators, i.e. photosynthetic physiology, chlorophyll fluorescence kinetics, senility and yield capability of intercropped crops, and compare the differences of physiological characteristics between sole and intercropped crops at various growth stages to further reveal the mechanism of density-tolerant property in intercropping systems; (2) investigate the spatio-temporal dynamics of light distribution and photosynthate accumulation of the population, analysis the influence of compact planting on intra- or interspecific relationships between intercropped components, and clarify the above-ground ecological mechanisms for density tolerance; (3) study the effect of different treatment on morphological indicators, e.g. plant height, stem diameter, leaf shape, LAI, leaf angle and azimuth, and reveal the morphological adaptation mechanism for density tolerance in intercropping systems; and (4) discuss the relationships between key agronomic practices with above-ground physiology, ecology and morphology indicators, and establish the agronomic regulation mechanism on densification and yield improvement through optimizing above-ground ecophysiological characteristics. This project will definitely contribute to provide vital theoretical basises for extending the compact planting effect and establishing production improvement techniques in intercropping systems based on biological interaction potentials.

密植是作物增产的简捷高效措施，但间作作物地上部生理、生态特征对密植的响应，以及这些响应对间作耐密性的影响研究薄弱，生产中缺乏进一步增密增效的理论依据。项目以小麦/玉米、玉米/豌豆为研究对象，在不同密度、带型、品种和施肥组合下：(1)研究作物光合生理、叶绿素荧光动力、衰老指标的动态变化，量化单作与间作作物在不同管理措施下的生理特征差异，明确间作耐密的生理学机制；(2)检测群体的光分布和光合产物累积时空动态，解析密植对间作作物种间互作和补偿生长的影响，理清间作耐密的地上部生态学机制；(3)研究作物株高、茎粗、叶倾角和方位角对间作和单作的响应差异，揭示间作耐密的作物形态学适应机制；(4)明确作物地上部生理、生态和形态学指标与产量的相关关系，构建基于地上部生理生态特征优化的间作增密增产调控理论。项目的实施将为深入挖掘间作密植效应，建立同步发挥作物自身和种间互作增产潜力的间作技术提供重要理论依据。

密植是作物增产的简捷高效措施，但间作作物地上部生理生态特征对密植的响应研究薄弱，生产中缺乏进一步增密增效的理论依据。项目以玉米||豌豆、小麦||玉米为研究对象，通过密度和施氮优化等方面研究了间作响应密植的地上部生理生态机制。.玉米间作豌豆较单作玉米具有更高的耐密性。相同占地面积下，间作较单作均具有增产效应。间作通过提高豌豆收获后玉米群体生长率、光合势和净同化率，延长玉米高光合持续时间，促进营养器官同化物向籽粒转运，是间作耐密的重要群体光合生理基础。豌豆收获后，间作玉米在不同密度下具有更高叶绿素相对含量和净光合速率，在高密下保持较高Fv/Fm，形成了耐密的叶片光合生理基础。间作提高豌豆收获后玉米气孔密度和指数，缓解高密导致叶片厚度降低的趋势，提高叶片叶绿体数量和基粒片层数，是间作玉米耐密的叶片解剖结构响应机制。豌豆收获后，间作玉米叶片光合关键酶基因表达上调，叶片光合关键酶活性增加，在基因尺度上揭示了间作响应密植的分子生物学机制。.小麦间作玉米较单作玉米具有更高的耐密性。间作较单作可提高小麦玉米净同化率、光合速率，间作净同化率随着玉米密度的增加而增大，但随着小麦密度增加与施氮量减小而降低；适度增大玉米密度，Fv/Fo与Fv/Fm增大而增强作物对弱光的适应。间作较单作玉米降低了群体中上部及中下部冠层透光率，且透光率随着玉米密度增加而显著降低。间作较单作提高了玉米花后叶片光合关键酶活性，弱化了减氮降低玉米光合关键酶活性的负效应。间作提高了叶片光合作用天线蛋白有关基因的表达量，提高了根系氮素代谢相关基因的表达量，从基因层面解释间作具有更强的光合和氮素利用能力。.总之，间作玉米较单作在豌豆与小麦收获后具有更高的光合关键酶活性及其基因相对表达量，提高了叶片净光合速率、群体光合势并促进干物质向籽粒转运，获得较高产量，增强了耐密性。本研究将为深入挖掘间作密植效应，建立同步发挥作物自身和种间互作增产潜力的间作技术提供理论依据。