保护性耕作对黄土高原果园土壤微生物的影响及调节机制

Because of local special climate, soil conditions and unreasonable agricultural managements, the Loess Plateau has always been facing with many severe issues about agricultural production and agro-ecology environment, such as shortage of agricultural water resources, barren soil and loss of water, soil and fertilizer, which have been extremely restricting the sustainable development of agriculture and the improvement of agro-ecological environment. Conservation tillage is an agricultural technique which is the most widely used in dryland farming and performs best all around the world，because it can effectively improve the soil quality and conserve soil and water.Therefore, researches on the application and mechanisms of conservation tillage in agro-ecosystem in this region will be of great significance. Based on the status of agricultural production and ecosystem in Loess Plateau as well as determining the ecological functions of soil microorganisms and soil physicochemical characteristics, this project will systematically and comprehensively study the dynamic changes and its regularity of soil microbial functional diversity,community structure and speices diversity under different conservation tillage models, by adopting molecular biological methods. This research is primarily designed to analyze the effect of conservation tillages on soil microorganisms and the principle of conservation tillages affecting soil microorganisms in Apple Orchards in this region,and provide theoretical basis for keeping sustainable development of agriculture and improving the agro-ecological environment in Apple Orchards in Loess Plateau of China,and offer the theoretical foundation for researches on soil microorganisms and biodiversity conservation.

由于特殊的气候、土壤条件以及不合理的农业管理措施，黄土高原一直面临着农业水资源短缺、土壤贫瘠和水土肥"三流失"等农业生产和生态问题，严重制约着该区农业可持续发展和农业生态环境改善。保护性耕作是世界上应用最广、效果最好的旱作农业技术之一，可以有效地改良土壤、保持水土，因此有关保护性耕作在黄土高原农业生态系统中的科学运用和作用机理的研究具有重要意义。本项目立足于黄土高原农业生产和生态系统现状，以苹果园土壤微生物为研究对象,结合土壤微生物生态功能特性和土壤理化性质的测定,应用分子生物学方法系统研究不同保护性耕作措施下土壤微生物的功能多样性、群落结构和种类多样性的差异及时空变化规律，分析保护性耕作对黄土高原果园土壤微生物的影响及调控机制，为改善果园生态环境、保持该区域果业可持续发展及土壤微生物多样性保护提供理论依据。

由于独特的地理位置和环境条件，黄土高原地区成为我国苹果产业的优势产区之一，苹果产业在黄土高原农业系统中占据着重要地位并成为该区域农民增收的支柱产业。然而由于特殊的气候、土壤条件以及不合理的农业管理措施的影响，严重制约了黄土高原果业可持续发展和果园生态环境改善。本项目立足于此，试图通过研究科学有效的果园管理措施来改善黄土高原地区果园的水肥条件，为该地区苹果提质增产提供一定的科学依据。本研究基于该地区现有资源，在保护性耕作研究基础上，选取了4种果园覆盖模式，对不同覆盖模式下果园土壤理化性质、酶活性；不同覆盖模式下土壤微生物群落结构及多样性；不同覆盖模式下果树生长状况以及果实产量品质进行分析，探讨不同覆盖模式对土壤微生物群落特征的影响及其与土壤理化性质及酶活性的关系，以期筛选出一种适宜该地区推广的高效果园覆盖模式。研究结果表明，较对照相比，覆盖显著改善果园土壤理化性质，在不同程度上显著增加土壤有机质和养分含量，显著增加深层土壤含水量和速效养分，降低土壤pH值，同时显著提高土壤脲酶、蔗糖酶和过氧化氢酶活性。荧光定量PCR结果表明，覆盖处理均能显著增加土壤细菌总丰度，氨氧化及反硝化功能基因丰度。Illumina HiSeq 高通量测序结果显示，覆盖措施对土壤真菌、细菌群落结构组成和多样性有较大影响。较对照而言，覆盖显著提高土壤微生物种类丰富度和微生物多样性。β多样性分析表明各覆盖处理和对照微生物群落系统发育组成存在显著差异。RDA分析表明，不同覆盖处理下土壤微生物群落相对丰度与土壤养分及酶活性存在一定相关关系。不同覆盖处理能显著提高果树净光合速率、叶绿素SPAD值、苹果果实产量和品质。可见，果园采取免耕覆盖耕作有利于该地区果业可持续发展。