The physiological and biochemical changes under the low temperature stress were studied with Taiwandalongqie,94-1 zaochangqie and Jinongshijixingchangqie.After 9 days treatment,the chilling injury index,electrolyte leakage of leaves and the MDA content of Jinongshijixingchangqie were the lowest,the content of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)were the highest,and the reduction extent of apparent quantum yield(AQY)and photochemical efficiency of photosystemⅡ(Fv/Fm)were the lowest,but ...