等渗Ca（NO3）2和NaCl胁迫对黄瓜砧用南瓜幼苗生长和活性氧代谢的影响

以黄瓜砧用黑籽南瓜和白籽南瓜幼苗为材料,通过营养液栽培研究了等渗Ca(NO3)2和NaCl胁迫对南瓜幼苗生长和活性氧代谢的影响。结果表明,不同盐胁迫下两砧木幼苗生长和抗氧化系统活性均受到不同程度抑制;与黑籽南瓜相比,白籽南瓜‘青砧1号’植株的生物量和SOD、POD和CAT活性均较高,而盐害指数、膜相对透性、MDA含量及O2.-产生速率则明显降低。等渗Ca(NO3)2和NaCl对两砧木南瓜幼苗的盐胁迫效应不同,Ca(NO3)2胁迫对砧木生长的抑制作用及盐害指数、膜相对透性、MDA含量、O2.-产生速率均小于等渗的NaCl处理,而其SOD、POD、CAT活性高于NaCl处理。可见,白籽南瓜‘青砧1号’具有较强的生长势和有效清除体内活性氧能力,有效降低膜质过氧化伤害程度,这是其耐盐性高于黑籽南瓜的重要原因;Ca(NO3)2处理使两砧木幼苗细胞受氧化损伤程度较轻,对植株生长的抑制程度明显低于等渗的NaCl。

Growth and Reactive Oxygen Metabolism in Different Cucumber Grafted Rootstock Seedlings under Ca(NO_3)_2 or NaCl Stress

Effects of Ca(NO3)2 and NaCl on the growth and active oxygen metabolism in Cucurbita ficifolia Bouche.and Cucurbita maxima×Cucurbita moschata(’Qingzhen No.1’) seedlings as cucumber(Cucumis sativus L.) rootstocks were investigated under nutrient solution.The results showed that the growth and antioxidative enzymes activities in both two kinds of rootstocks were inhibited to varying degrees under different salt stress.Comparing with Cucurbita ficifolia Bouche.,’Qingzhen No.1’ had higher biomass and activities of SOD,POD and CAT,whereas the salt injury index,plasma membrane relative conductance,MDA content and O-·2 production rate were significantly lower than that of Cucurbita ficifolia Bouche.At the same time,iso-osmotic Ca(NO3)2 or NaCl stress induced different salt effect to the rootstock seedlings.The inhibitory effects in salt injury index,plasma membrane relative conductance,MDA content and O-·2 production rate were significantly lower under Ca(NO3)2 stress than that under NaCl stress,whereas the activities of SOD,POD and CAT were higher under Ca(NO3)2 stress than that under NaCl stress.It was observed that ’Qingzhen No.1’ had higher salt tolerance than Cucurbita ficifolia,mainly because of stronger growth potential and effectively removing the reactive oxygen species and reducing the damage from membrane lipid oxidative.Ca(NO3)2 stress caused less membrane-lipid peroxidation and inhibition for plant growth than that of iso-osmotic NaCl stress.