Study On Drought Resistance And Cold Resistance Of Eight Alfalfa Varieties

Alfalfa(Medicago sativa L.)is one of the most important leguminous forage in our country.Saline soils and water severely limit the productivity of crop and pasture lands in semiarid and arid environments.Investigating the stress resistance of alfafa is a partial solution to this problem.This study measured the salt resistance and drought resistance of 8 alfalfa species,including Medicago sativa L.cv.'Xinmu No.2',Medicago sativa L.cv.'Suntory',,Medicago sativa L.cv.'Sadie No.5',WL-168,WL-712,WL-656,WL-903,WL-343,aiming to provide a theoretical basis for the planting of Medicago sativa.The results showed that:1.Artificial soil drought stress was carried out by 10%PEG on 8 different alfalfa varieties,and the drought resistance index of root length,shoot height,FW/DW ratio,membrane relative permeabil-ity,proline content and relative water content were measured.The results showed that:The shoot height and root length are significantly decreased,which declined from 3.77 to 15.89%,from 8.87 to 29.4%,respectively.However,the proline content showed rising trend compared with control,resulting in FW/DW ratio and the relative water content decreased.Meanwile,the degree of drought resistance of 8 alfalfa species was in the following order:WL-168,Medicago sativa L.cv.,'Xinmu No.2',WL-712,Medicago sativa L.cv.,'Sadie No.5',WL-343,WL-656,WL-903,Medicago satiiva L.cv.'Suntory'.2.Treated by low temperature at 4?,the root length,plant height,ratio of fresh weight to dry weight and relative electrical conductivity of alfalfa seedlings(with 3 true leaves)were measur ed at 3,5 and 7day.The research shows that the 8 varieties of alfalfa seedlings roots shortenin g(5.96%-21.51%),the plant height reducing(5.56%-15.88%)with significant difference(p<0.05),and the ratio of fresh and dry weight obviously decreased(21.18%-36.64%)(p<0.05);bec ause of the low temperature damage to the cell membrane,the relative electrical conductivity of the treated group was remarkable higher(20.94%-37.50%)than that of the control group(p<0.05).The cold resistance of eight alfalfa varieties was ranked,and the strongest cold resistance was Medicago sativa L.cv.'Sadie No.5',the weakest was WL-903,and the cold resistance strength of other varieties in turn were WL-168,WL-712,Medicago sativa L.cv.'Xinmu No.2',WL-343,Medicago sativa L.cv.'Suntory',WL-656.In this study,the drought resistance and cold resistance of eight alfalfa varieties were studied.The results showed WL-168?WL-712 and 'Sadie No.5' represented the best drought resistance and cold resistance.The results could provide some scientific basis for the cultivation of cultivars in China.