间作体系作物根系生长、空间分布和形态变化的机理研究

植物种间相互作用是植物生态学研究中的热点问题,而根系相互作用是关键。该课题依据我们在前期研究中观察到的蚕豆/玉米种间促进及其地下部根系的互趋生长，小麦/玉米间的种间竞争及其地下部根系生长趋避分布的现象，结合国际上资源竞争与根系识别研究的最新进展，提出了种间促进和竞争介导的根系生长空间分布和形态变化的科学假设：1）种间竞争或促进引起的土壤养分有效性降低或增加，对间作体系作物根系生长、形态分布产生负或者正的效应；2）植物种间通过根系分泌的某些信号物质相互感受彼此的存在，并且决定根系的生长是相互合作还是排斥；3）根系分泌物中的某些化学物质（植物激素类、异羟肟酸类、酚酸类等）在根系种间识别中作为信号物质起关键作用。拟通过田间原位试验，室内模拟试验（活性炭、根箱分根、拉根、砂培和琼脂无菌培养等技术）结合根分泌物收集、HPLC或者HPLC-MS分离鉴定等技术，证实这个科学假设。阐明种间根系互作的实质。

Interspecific interactions is one of key issues and hotspots in research of plant ecology, where root interactions are one of key issues. Based on previous observations that the root growth is either intermingling in faba bean/maize intercropping where interspecific facilitation was found above-gound or avoidance in wheat/maize intercropping where interspecific competition was found during co-growth stages, and combined with the recent findings in roots recognition between plants via root exudates. We proposed the hypothesis that 1) Altered nutrient availability derived from interspecific competition or mobilization causes changes of root growth, distribution, so called resource competition or mobilization pathway; 2) Plant roots are able to recognize neighbour's presence via root exudates, and decide to either intermingle or avoidance of the root growth; 3) Some components (such as plant hormone, hydroxamic oxime acids，phenonic acids) in root exudates may play an important role in root recognition between different species. The project will test the hypothesis, employing methods of field experiments with intercropping applied different levels of N and P fertilization,in which root growth, distribution and morphological parameters will be responded to both interspecific interactions and nutrient availability. Responses of roots to root exudates of neighbor species will be compared by eliminating root exudates via adding activated carbon into culture media in root boxes, and will test the root response to single root contact without nutrient effects by spliting root technique in sand culture. We will collect root exudates by either agar or solution culture in growth chambers, and identify key chemical components in root exudates by HPLC or HPLC-MS techniques. The study will systemically elucidate the mechanisms on interspecific interactions, in terms of both the resource competition and mobilization, and the roots recognition.