猫尾草新品系幼苗对低温胁迫的响应OA

This study investigated the responses of three newly developed timothy(Phleum pratense)lines(P1,P2,and P3),three introduced cultivars(7019,8735,10027),and two local cultivars('Minshan'and'Chuanxi')to low temperature stress.Seedlings were subjected to 4℃,0℃,and-4℃for seven days,after which morphological,photosynthetic characteristics,and physiological parameters were measured to elucidate the mechanisms underlying cold tolerance.The results showed that decreasing temperature signifi-cantly reduced plant height,leaf morphology parameters(length,width,and area),relative water content,catalase activity,chlorophyll and carotenoid contents,transpiration rate,net photosynthetic rate,and sto-matal conductance.In contrast,malondialdehyde,proline,soluble sugar,and soluble protein contents increased markedly under low temperature stress.Superoxide dismutase and peroxidase activities displayed a biphasic pattern,reaching maximum values at 0℃and declining at lower temperatures.Intercellular car-bon dioxide concentration first decreased and then increased,with the lowest value observed at-4℃.Com-prehensive evaluation indicated that P2 and P3 exhibited the strongest cold resistance,whereas cultivars 7019 and 10027 were the most sensitive,and the remaining cultivars showed intermediate tolerance.Lin-ear regression analysis identified proline content,net photosynthetic rate,leaf area,leaf width,catalase activity,chlorophyll content,and malondialdehyde level as key indicators for evaluating cold resistance in timothy.These findings provide a theoretical basis for the selection and breeding of cold tolerant timothy cultivars.