【作者】 李淑敏；

【导师】 张福锁；

【作者基本信息】 中国农业大学 ， 植物营养学， 2004， 博士

【摘要】 间套作是我国农民在长期生产实践中，逐步认识和掌握的一项耕作措施，具有充分利用资源和大幅度增加产量的特点。磷是不可再生资源，是我国乃至世界农业生产最重要的限制因素。选择合适作物种类进行间作，可提高作物对磷的利用效率。因此间作在解决人口不断增长、资源日益枯竭利生态环境恶化等问题方面具有重要的现实意义，越来越受到农学家和生态学家的关注。本研究在田间观察现象的基础上利用水培模拟间作和根系分隔技术，研究玉米／鹰嘴豆、玉米／蚕豆两种间作体系作物活化吸收土壤有机磷和难溶性无机磷的种间促进作用机制，为提高间作体系生产力和资源利用效率提高科学依据。本试验主要获得以下结论。 玉米／鹰嘴豆和玉米／蚕豆间作体系中，在供应有机磷条件下鹰嘴豆和蚕豆利用有机磷的能力强于玉米，玉米／鹰嘴豆和玉米／蚕豆间作体系吸磷总量高于相应单作总和。无论水培还是土培试验，与鹰嘴豆间作和与鹰嘴豆根系不分隔的玉米生物量显著高于单作和与鹰嘴豆根系完全分隔的玉米生物量，鹰嘴豆促进了玉米对有机磷的活化吸收；水培条件下，间作玉米吸收有机磷比单作增加116.7％，间作鹰嘴豆吸收有机磷比单作减少14.7％：土培条件下，与鹰嘴豆根系隔尼龙网和不分隔玉米的总吸磷量和地上部磷浓度分别比根系完全分隔处理增加118.0％，43.7％，28.1％和10.2％：缺磷和施有机磷使作物根系和根际土壤酸性磷酸酶活性显著增加，但鹰嘴豆的根系和根际土壤酸性磷酸酶活性显著高于玉米，在间作体系中对促进玉米吸收有机磷起重要作用。 在土壤灭菌条件下。以有机磷为磷源在蚕豆／玉米间作中同样间作吸磷总量高于单作，菌根真菌在磷吸收的种间促进中没有起到明显作用，磷吸收的种间促进作用是根系相互作用的结果；但菌根真菌显著增加玉米和蚕豆根际土壤酸性和碱性磷酸酶活性，促进玉米和蚕豆对有机磷的吸收，接种菌根真菌后玉米和蚕豆的吸磷量是对照的2.38和1.82倍，同时接种菌根真菌和根瘤菌对蚕豆的生长有协同促进作用，蚕豆根瘤数增加，菌根侵染率提高，同时也改善了与之间作玉米氮素营养，对玉米生长起到间接促进作用。 玉米／蚕豆间作根系分隔试验结果表明，蚕豆对难溶性Fe-P和Al-P的利用能力强于玉米，其可能的机理为蚕豆酸化根际土壤，并有较高比吸收速率；以Fe-P和Al-P为磷源时，蚕豆对Fe-P和Al-P的回收率分别是玉米的4.13和1.06倍；间作后蚕豆改善玉米根际的微域环境，使玉米根际土壤pH降低，比吸收速率增加，根系变长，总吸磷量平均比根系完全分隔增加33.0％。进一步试验表明，蚕豆对玉米吸收磷的促进作用可能是根系分泌物的作用。更多还原

【Abstract】 Intercropping, a commonly used agronomic practice by farmers in China for a long time, can use nutrient and water resources efficiently and enhance crop yield enormously. Phosphorus is a kind of unrenewable resource and second only to N as the most limiting element for plant growth all over the world. Phosphorus use efficiency can be improved by selecting suitable crop intercropped. Therefore, intercropping plays an important role in solving contradicts between ever increasing population and deteriorate ecological environment due to shortage of resources, and attracts more and more agronomists and ecologists attention. So hydroponic culture and technique of different root barriers were carried out to study the mechanism of interspecific facilitation on P uptake by crops from organic phosphorus and sparingly soluble phosphorus forms in soils in maize/chickpea and maize/faba bean intercropping systems based on observation of field experiments. The objective of the research work was to give scientific evidences for improving productivity and higher efficient resource utilization in intercropping system. The following results were obtained in the experiments.The ability of chickpea and faba bean supplied with phytate to mobilize organic P were stronger than maize in maize/chickpea and maize/faba bean intercropping systems. The biomass of maize intercropped with chickpea or without root barriers was significantly higher than that of monoculture one or with solid barrier in hydroponic culture or soil culture. Chickpea facilitated phosphorus uptake by associated maize from an organic P source. Total P uptake in maize/chickpea and maize/faba bean intercropping systems was significantly higher than that of monoculture. In hydroponic culture total P uptake from organic P source by intercropped maize was increased by 116.7% over monoculture and total P uptake by monoculture chickpea was decreased by 14.7% compared to monoculture one. In soil culture, P uptake by maize and P concentration in maize shoots was greater 118.0%, 43.7% 28.1% and 10.2% with mesh barrier and with no barrier than with solid barrier, respectively. Acid phosphatase secreted by chickpea and maize and soil acid phosphatase activity in the rhizosphere of maize and chickpea were significantly increased due to P deficiency and phytate supplied. Acid phosphatase activities of chickpea were higher than those of maize and played important role in P uptake from an organic P source in maize/chickpea intercropping system.In sterilized soil condition, total P uptake in maize/faba bean intercropping was significantly higher than monoculture supplied with organic P. Mycorrhizal fungus didn’t play significant effects on interspecific facilitation for phosphorus uptake, and the facilitation was due to the interspecific root interaction. But phosphorus uptake by maize and faba bean inoculated with AM fungus was 2.38 and 1.82 as much as to the control because acid phosphatase activity and alkaline activity in the rhizosphere of maize and faba bean inoculated with AM fungus increased. Symmetrical effect on P uptake from organic P was observed when faba bean was dual inoculation with AM fungi and Rhizobium leguminosarum. Number of nodules, weight of nodules and mycorrhizal colonization of faba bean weresignificantly increased. At the same time the growth of associated maize was significantly facilitated indirectly due to improvement of nitrogen nutrition.The mechanism of better ability of faba bean in mobilizing sparingly soluble Fe-P and Al-P in maize/faba bean intercropping was conductive to acidify the rhizosphere soil and to be higher specific absorption rate of phosphorus. When Fe-P and Al-P were supplied phosphorus fertilizer recovery of faba bean was 4.13 and 1.03 times as much as that of maize, maize. Root length and specific P absorption rate of maize were significantly greater while rhizosphere pH was lower when roots of the two species grew together than when roots of the two species were separated, which lead to total P uptake by maize with更多还原