集约化农田丛枝菌根真菌群落构建机制及驱动因子分析

The community composition, diversity and function of key soil microbials in the agriculture soil is of great significance for the understanding of the biological process of high nutrient use efficiency in soils, and for the realization of high yield crop production and the development of sustainable agriculture. Arbuscular mycorrhizal fungi (AM) is a group of important beneficial microbials in the soil, however, the knowledge of community construction of AM fungi in intensive agriculture soils is still very lacking. The research topic is becoming one of the hot spots in mycorrhiza ecological studies. This project is aimed to investigate the composition and diversity of AM fungi in the long-term field experimental site in Quzhou,Heibei,where many field trials on fertilisation and tillage have been conducting for many years.Large sampling will be carried out in the fertilisation (inorgainic and organic fertilisers) field trials, and tillage treatment will also be included. In addition to the commonly used molecular techniques,the advanced 454 pyrosequencing technique will be employed. The mechanism of community construction of AM fungi in soil will be studied by means of modelling method which has been widely used in plant community studies. The key functional AM fungi communties in plant roots and in active hyphae in the soil will also be evaluated by using the molecular methods. Taking together the information from soil, plant roots and hyphae in the soil (functional AM fungi), the project will give an overall evalution of the diversity of AM fungi in intensive agriculture and its potential ecological function in the agroecosystem. The research work will provide important theoretical guidelines for the development of suitable agricultural practice for the rhizosphere management to fully realize the function of beneficial microbials in intensive agriculture soils.

对农田地下生态系统中关键微生物多样性和功能的认识对理解养分资源高效利用的生物学过程，实现作物高产和农业可持续发展非常重要。丛枝菌根真菌是土壤中一类非常重要的微生物，然而对集约化农田丛枝菌根真菌群落构建的机制还缺乏认识，目前正成为国际上菌根生理生态学关注的一个热点。项目将以长期进行集约化农业生产研究的河北曲周长期定位站试验样地为采样区，选取不同农艺措施处理进行农田大范围采样，采用454高通量测序和其它分子生态学技术，系统研究外部投入（化肥、有机肥）和耕作对土壤丛枝菌根真菌群落结构和多样性的影响；采用群落生态学分析方法，建立集约化农田菌根真菌群落构建的理论模式，并进行驱动因子分析；结合植物根内以及土壤中关键功能菌根菌的多样性特征，从系统发育进化角度，对农田功能菌根菌的生态功能进行综合评价，为进一步通过改良农业措施，实现根际定向调控，充分发挥和挖掘土壤有益微生物的生态功能提供重要的理论科学依据。

高产高效是华北平原集约化农业生产的目标，长期以来大量化肥投入是该地区作物高产的一项重要农艺措施，然而由于高投入化肥引起的环境问题和资源浪费已成为该地区农业发展的主要制约因子。丛枝菌根真菌（arbuscular mycorrhizal fungi,简称AMF）是土壤中一类重要的有益微生物，但集约化农业生产体系中菌根的效应尚不明确，一个基本核心的问题是土壤中菌根真菌的群落特征及其驱动因子还不清楚。本项目研究目标是明确集约化农田生态系统中菌根真菌多样性和群落结构特征，分析AM真菌群落构建的驱动因子，提出群落构建的理论，并对集约化生产体系菌根真菌的生态功能进行综合评价，为实现对农田土壤中菌根真菌的定向调控，充分发挥其对作物生产的作用提供理论科学依据。选取华北代表性的长期定位磷肥、氮肥和有机肥试验田块开展试验。主要结果如下：.a)土壤中AM真菌的群落结构受施肥（氮肥、磷肥和有机肥）的影响，施肥主要通过影响土壤理化性状影响ＡＭ真菌群落结构。除目标施肥（如氮肥和磷肥）外，AM真菌的群落结构是各种因子综合作用的结果，尤其是有机肥处理。因此研究长期施肥对土壤AM真菌群落结构的作用，不能单纯研究某一元素的作用，需要考虑各种因子的交互作用和综合效应。.b)底层土壤AM真菌较丰富，底层土壤AM真菌嵌套在表层土壤中，一些稀有种类在底层土壤中丢失。.c)玉米根系菌根真菌物种丰富度显著低于土壤中AM真菌。根系菌根真菌的群落结构主要受作物生育期的影响。菌根真菌诱导玉米磷转运蛋白基因的表达对外界磷的供应量敏感，对氮肥施用不敏感。.d)大田条件下AM真菌的群落结构较符合生态位理论，作物特性和土壤理化性质共同影响ＡＭ真菌的群落结构。.e)菌根真菌的根外菌丝具有一定的可塑性，高磷抑制其生长，在低磷区菌丝恢复生长。ＡＭ菌根共生体存在植物光合碳优先分配，但共生体C-P的优先分配受土壤中磷供应强度的影响。.f)大田土壤接种土壤ＡＭ真菌的效应受多种因素的影响，如接种剂的数量以及微生物适应性等的影响。大田条件下如何发挥有益微生物的作用，还需进一步优化措施。.