Preliminary Study On The Regulation Of Italian Ryegrass Growth,Cadmium Uptake And Transport Under Cadmium Stress

With the development of industry and agriculture,the problem of soil cadmium(Cd)pollution is getting worse.As a fine pasture,Italian ryegrass has strong heavy metal enrichment and bioenergy conversion potential.By planting Italian ryegrass on Cd-contaminated land,while repairing the soil,it can also increase economic benefits.The objectives of this study were Exploring synergy to promote the growth of Italian ryegrass and the accumulation of Cd by IRR(Italian ryegrass-rice rotation),mowing and PGPB(Plant growth promoting bacteria).1.Field IRR experiment with Italian ryegrass(PRINE)and rice(C Liangyou 651)in Cd-contaminated areas of Chenzhou,Hunan Province.Soil Cd content is 2.21 mg kg-1 in Hunan.At the same time,set up the soil culture experiment with the Cd soil in Hunan.Explore the effects of IRR patterns and mowing on Italian ryegrass,rice growth and their Cd accumulation.Under field conditions,mowing can increase the yield of Italian ryegrass and also significantly reduce the Cd content of Italian ryegrass on shoot after mowing.And the acid-soluble cellulose in the ryegrass increases after mowing,which improves the efficiency of ethanol fermentation.Compared with the winter leisure area,planting rice in areas where Italian ryegrass is grown can reduce Cd content in shoots and seeds of rice,and the soil Cd concentration has also been temporarily reduced.However,due to the complex environment in Daejeon,the differences between the different treatment groups did not reach significant.Under soil culture conditions,the biomass and Cd accumulation of Italian ryegrass in the mowing area increased significantly.Planting rice in the Italian ryegrass region can significantly reduce Cd accumulation on shoot and seeds of rice.The Cd concentration of soil has also been reduced.Therefore,mowing can promote the growth of Italian ryegrass and the accumulation of Cd.The IRR model is conducive to improving rice quality and Cd-contaminated soil restoration.2.The laboratory preserves eight PGPB(Plant growth promoting bacteria)screened from shoots and roots of plant from Cd-contaminated land.Setting Cd and Cd-free conditions under hydroponic conditions to explore the ability of PGPB to promote Italian ryegrass growth and accumulation of Cd.And select the best PGPB to promote the growth of Italian ryegrass and to relieve Cd stress.Under the condition of Cd-free,all of them could significantly increase the biomass of Italian ryegrass.Under Cd treatment,all PGPB had the ability to alleviate Cd stress.Compared with the control,chlorophyll and biomass increased significantly,and MDA content decreased significantly.PGPB can also significantly reduce the Cd content in the shoot and root of Italian ryegrass.However,due to the increase about biomass of ryegrass,the cadmium accumulation of the whole ryegrass treated by endophytes increased significantly.Using the membership function and various indicators,it is screened that Le14,Bc09 and Oj24 have the best promoting effect under Cd-free conditions.Under Cd conditions,Bc09,Oj24,Le14 and Ps14 have the strongest ability to alleviate Cd stress.3.Through the experiments,it was found that mowing and PGPB can promote the growth of Italian ryegrass under Cd treatment.Therefore,set up the soil culture experiment.Soil culture was selected from Cd contaminated soil in Hunan,and the Cd content was 2.8 mg kg-1.Selecting three PGPBs that have the best ability to alleviate Cd stress(Bc09,Oj24 and Le14).And setting mowing condition to explore the ability of PGPB in soil culture and field environments and synergy with mowing measures.In the absence of Cd and Cd-free,both mowing and PGPB significantly increased the tillering of Italian ryegrass.Compared with the control,PGPB can significantly alleviate Cd stress,and the effect in the mowing area is more significant.Mowing can reduce the Cd concentration of ryegrass after mowing,but increase the total Cd accumulation of ryegrass.IRR mode can reduce Cd pollution in rice and improve rice quality.Mowing measures and PGPB can promote the growth of Italian ryegrass under Cd treatment.Mowing measures and some PGPB can also promote the absorption of Cd by Italian ryegrass and enhance the ability of Italian ryegrass to repair Cd-contaminated soil,which has a very good application prospect.