Evaluation On Heat Tolerance And Freezing-tolerance And Filtration Of Welsh Onion Varieties

Welsh onion (Allium fistulosum L.) belongs to Lily family, Allium genus, and is biennial plants. In recent years, the requirement tend to anniversary serve. Meanwhile it has changed from once batch to several batches one year. But the studies on the Heat Tolerance over summer and Freezing-tolerance in late winter and early spring are few. Therefore, people did some researches about comparison and evaluation and on this basis they studied the alimentation quality and botany character and the relation to Heat Tolerance and Freezing-tolerance. The main findings are as follows:1.We studied the heat tolerance of different Welsh onion varieties,The Results indicated that electrolytic leakage and malondialdehyde content of Welsh onion leaves increased under high temperature stress, superoxide, peroxidase and catalase activities changed remarkably. The content of pervasion substance increased. The hot injury index rise with time lengthens under high temperature stress, but the changes of different Welsh onion varieties were different in range.This indicated the remarkable differences of heat tolerance among different Welsh onion. arieties have existed. Through calculating the function data of heat-tolerant-related physiological index, and comprehensive evaluation on heat tolerance, the conclusion came to that"Xiabao"and"Baojihei"in heat tolerance are stronger,"Longyao"and"Eluosi"are relatively worse.2.We studied the freezing-tolerance of different Welsh onion varieties .The results indicated that electrolytic leakage and malondialdehyde content of Welsh onion leaves increased under low temperature stress, superoxide, peroxidase and catalase activities changed remarkably.the content of pervasion substance increased.the content of chlorophyll and quality ratio of chlorophyllA and chlorophyllB reduced, the quality ratio of free to binded water reduced, the cold injury index rise with time lengthens under low temperature stress,but the changes of different Welsh onion varieties were different in range.This indicated that the remarkable differences of among different Welsh onion varieties on freezing-tolerance existed.. Through calculating the function data of freezing-tolerant-related physiological index, and comprehensive evaluation on freezing-tolerance, the conclusion came to that"Eluosi"and"Heifen310"in freezing-tolerance were stronger,but"Xiabao"and"Longyao"were relatively worse.3.The experiment showed that the dark green leaves have much lardaceous power and the olivine leaves have little lardaceous power, leaves colour and lardaceous power are relation to the Heat Tolerance and freezing-tolerance, but the alimentation character has no relation to the Heat Tolerance and freezing-tolerance.4.Through observation and investigation on 13 Welsh onions which picked out From practice, this experiment screened out several Welsh onion varieties which had better quality, such as"Xiabao","Xiahei","Baojihei"in hot tolerance and"Eluosi","Jiwanchou","Heifen310"in freezing-tolerance. They all could be generalized.