亏缺灌溉时小桐子对盐胁迫环境的响应与水氮高效利用机制研究

At present, water shortage and soil salinization is still two key factors impose restrictions on the development of agricultural sustainable and improvement of ecological environment, saline land area has reached 3.6 million hm2 in China, and mainly distributed in the arid and semi-arid and coastal areas. Phytoremediation of salt-stress soil is one of the most effective way to make improvement of saline soil. Jatropha curcas has strong ability of resistance to environment of salt stress, but so far there are some basic scientific problem is not clear, that is to say, which may improve remediation efficiency of salt-stress soil. This research projects have taken into account the actual situation of seasonal drought in yunnan province, some biological characteristics and root distribution characteristics of Jatropha curcas and the present situation of salt-stress soil in China, this research project’s key problem is to study the migration regularity and distribution characteristics of salt-stress ions in root zone soil and the ability of root adsorption to salt-stress ions and the accumulation in all organs, and the effect of salt-stress soil on the growth, soil water and nitrogen migration, the root absorption and utilization to water and nitrogen of Jatropha curcas under deficit irrigation and different nitrogen conditions, and to explore the reparative potentiality of Jatropha curcas for salt-stress soil and the regulation and control effect of water and nitrogen under deficit irrigation condition. The aim of this study is to improve the remediation efficiency of Jatropha curcas for salt-stress soil, based on the root growth characteristics of Jatropha curcas, the growth and physiological regulation mechanism and the environment characteristics after the soils by salt-stress, to find a best water supply index and water and nitrogen coupling model, which is beneficial to the Jatropha curcas for salt-stress soil remediation, so realized the theory and technology innovation for plant of resistance to salt stress making the best of utilization to water and nitrogen in the saline soil area, thus a new way will be opened up for phytoremediation of salt-stress soil and reuse of salt-stress ion, and the result can also provide a theoretical basis for the reasonable management of water and nitrogen in the salt-stress soil.

植物修复被认为是盐胁迫土壤修复的最有效方法。小桐子具有较强的抗盐分胁迫能力，但有利于提高盐胁迫土壤修复效果的一些基础科学问题研究还不清。本项目研究紧密结合盐碱区用水实际、小桐子的生物学特性和根系分布特征及土壤盐碱化的现状，重点研究亏缺灌溉和不同施氮条件下盐分离子在小桐子根区土壤中的迁移规律和分布特征及根系的吸收和各器官的累积能力，以及生长、生理、根区水氮分布与利用对盐胁迫土壤的响应，从机理上探索亏缺灌溉条件下小桐子修复盐胁迫土壤的潜力及水氮调控的效应，以提高盐胁迫土壤的修复效果为目标，依据小桐子根系生长和分布的特征、生长生理调节机制和盐胁迫土壤环境的特点，构建有利于小桐子修复盐胁迫土壤和产量提高的最佳供水指标和水氮耦合模式，这将会实现盐胁迫环境中抗盐作物水氮耦合高效利用理论的创新，为盐胁迫土壤的植物修复和盐分离子的再利用开辟一条新的途径，也为盐胁迫土壤中合理的水氮管理提供理论依据。

如何通过最佳水氮耦合方式，调节盐碱区和重金属污染区小桐子生长，提高盐碱和重金属污染土壤的修复效果和植被恢复，对我国盐碱区和重金属污染区的植物修复和植被恢复具有重要的现实意义。本项目依据我国云南小桐子种植区水资源短缺及分布不均，盐碱区和重金属污染区水肥环境脆弱的现状，重点研究亏缺灌溉条件下不同氮素供应对盐碱区和重金属污染区小桐子的生长、生理、耐盐机理、形态特征、耗水特性、水分传输、土壤水氮盐迁移、植株水盐吸收及水氮利用的影响。研究发现不同水量交替灌溉会促进小桐子提高抗盐胁迫能力和修复效果。在适宜的土壤水分条件下，大田生长的小桐子最大的耐受NaCl胁迫的含量为0.8%，虽然在此条件下小桐子树受到一定的影响，但还是能较快生长，表现出较强的抗盐胁迫能力，添加氮肥会缓解盐胁迫的不利影响。本试验条件下促进小桐子较快生长，提高修复效果的最佳组合为，灌水定额为1.0m3，每棵树的施氮量为200g。在田间进行的铅胁迫下小桐子水分调控效应试验发现，有利于小桐子提高修复效果的适宜的灌水量为0.8-1.0m3。同时我们也发现，两年试验结束后，未进行补充灌水和施肥管理，在盐胁迫条件下，小桐子受到水分和盐的双重胁迫，叶片发黄和局部变干，虽然能存活，但生长基本停止。小桐子具有极其的抗干旱和盐双重胁迫的能力，可能的原因是通过减小气孔开度、脱落下层叶片，减少叶面积降低蒸腾量，也通过增加根系和冠层水分传导、根冠比和胡伯尔值提高根系向冠层传输水分和养分的能力，特别是利用其体内部有类似海绵状的物质贮存更多的乳白色酸性液体，不仅提高贮存水调节能力，而且通过酸碱中和提高了抗盐胁迫能力。同时，在本项目支持下研发了水肥一体化灌溉装备。该项研究对采用小桐子修复盐碱和重金属污染土壤实施亏缺灌溉和水氮耦合技术提供理论与技术支撑。