不同生育期咸水灌溉对甜瓜叶片膜脂过氧化及保护酶活性的影响

采用砂培法在甜瓜不同生育时期用不同浓度咸水灌溉条件下,研究甜瓜叶片膜脂过氧化和保护酶活性的变化.结果表明,甜瓜叶片丙二醛(MDA)含量随咸水浓度的增加和处理时间的延长而增加,并且处理时期越早其含量越低;叶片细胞膜伤害率(MIP)在持续处理中随浓度增加而上升,而在其它处理中呈先下降再上升的趋势;各处理的CAT活性均高于对照,随咸水浓度的增加,CAT活性表现出先上升后下降的趋势,而SOD和POD活性基本上都是持续下降的趋势.研究发现,甜瓜在不同生育期所适宜灌溉咸水的最大浓度不同,其中伸蔓期约为7 g/L,开花坐果期和果实发育期约为5 g/L;不同保护酶的活性在咸水灌溉条件下变化规律不一致,不能有效反映甜瓜对咸水灌溉的适应程度.

Effect of Brackish Water Irrigation on Membrane Lipid Peroxidation and Protective Enzyme Activities in Melon Leaves of Various Developmental Stages

In sand culture condition,the melon was supplied with different concentrations brackish water at four different developmental stages to study the changes of membrane lipid peroxidation and protective enzyme activities in leaves.The results indicated that the average content of MDA increases as the concentration increased of the irrigation water and the time of treatment prolonged and it correlates with the starting time of treatment.The MIP value declined before the treatment concentration reached 5 g/L and went up when the concentration of the irrigation water beyond that but in the throughout treatment the MIP increased as the concentration became higher.The activity of CAT rose at first and then decreased as the brackish water concentration increased and that of all the treatments are higher than that of the CK.The SOD and POD activity fluctuated with the concentration in different treatments while the general trend is decline.Our study indicated that the ultimate concentrations,which the plant can stand without degraded yield and quality,varied with the development stages,for the straw period is about 7 g/L and for the flor-fruit and fruitage stages are approximately 5 g/L.There is no regularity of the activities of protective enzyme which can not indicate the degree the plants adapted to the brackish water.