The Research On Response To Cadmium Stress Of Rice Under The Infection Of Arbuscular Mycorrhizal Fungi

With the development of the industry in our country, cadmium pollution weretaken into the soil through various channels, that caused soil contaminated more heavily.According to statistics, there are more than200000hm2farmland area contaminatedwith cadmium, accounted for1/6of the total cultivated land area. Because of thelong-term retention and degradability of cadmium in soil, therefore,it has a highenvironmental security risk.The heavy metal will also be accumulated by crops to enterthe food chain, which is harmful to human health. Rice can be enriched by cadmiumeasily, and it is a kind of main food crops in China at the same time.In view of the situation above, this experiment was set five cadmium concentrationgradient (0,0.5,1,2,5mg·kg-1) to put into the soil, according to the soil cadmiumcontent of typical sewage irrigation area and environmental quality standard for soils.Under the certain cadmium concentration, the rice was inoculated with two kinds ofArbuscular Mycorrhizal Fungi (AMF)-Glomus mosseae（GM）and Glomus intraradices（GI）to investigate the improvement of rice growth, photosynthesis and waterefficiency,as well as the migration of cadmium in soil-plant-root system.In order toprovide a theoretical basis for practical application.The result showed that, AMF can infect rice effectively under differentconcentrations cadmium treatment,the average infection rate of Glomus mosseae is48.53%higher than42.61%of the Glomus intraradices. And the infection rate withdifferent AMF treatment both decreased with the increase of Cd content, but goodsymbiotic relation could be formed under different Cd concentration. Besides, AFMinoculation could help growth of rice, and under stress of high-concentration of Cd（5mg·kg-1）, AMF could relieve the inhibition of plant height under Cd stress. In contrastwith blank control group, GM and GI plant height increased by respectively13.8%and10.3%, and biomass enhanced by respectively14.69%and13.38%.Utilization rate of strong light will be improved significantly by Arbuscularmycorrhizal fungi infection under Cd stress, when Cd concentration reached5mg kg-1,Pnmaxof GM and GI wil be improved by48.9%and24.0%respectivelycompared to blank group. In addition, water utilization efficiency will be improvedsignally,the average of WUE under GM and GI treatment has been increased by 6.90%and4.43%compared to CK treatment.AMF infection made stress-relatedphysiological indicators tended to be normal, fluctuation is significantly steadycompared to control group within a certain range of Cd concentration.It can be inferredthat AMF promoted the Cd tolerance effectively.AMF infection treatment also influenced the transportion and distribution of Cd inplants and roots. Two kinds of AMF treatments can all fix Cd in roots and reduceupward transfer, effectively reduced the Cd accumulation in rice plants,and promotedthe fixation process of rice. For different content of Cd, transportion coefficient of highconcentration was higher than low concentration. For same Cd concentration, Glomusintraradices can fix the cadmium in roots better than other treatment.