NaCl胁迫对西瓜嫁接苗叶片抗氧化酶活性及光合特性的影响

Activities of Antioxidant Enzymes and Photosynthetic Characteristics in Grafted Watermelon Seedlings under NaCl Stress

以耐盐性较强的葫芦品种‘超丰抗生王’为砧木,耐盐性较弱的西瓜品种‘秀丽’为接穗,采用营养液水培法,研究了NaCl胁迫对西瓜自根苗和嫁接苗保护酶活性、膜质过氧化及光合特性的影响。结果表明,NaCl胁迫下,嫁接苗和自根苗生物量显著下降,但嫁接苗下降幅度小于自根苗;NaCl胁迫抑制了西瓜自根苗和嫁接苗的气体交换参数,但是嫁接苗的净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)及叶绿素含量显著高于自根苗;NaCl胁迫下西瓜嫁接苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均显著高于自根苗,丙二醛含量较自根苗低。上述结果表明,NaCl胁迫下嫁接苗通过维持较高的抗氧化酶活性来提高清除活性氧(ROS)的能力,从而降低氧化损伤,并保持较高光合速率,从而增强西瓜幼苗对盐胁迫的耐性。

The changes of protective enzyme activities, lipid peroxidation and photosynthetic characteristics were studied in grafted and own-root watermelon seedlings under NaCl stress using calabash cultivar ＇Chaofengkangshengwang＇ as stock and salt intolerant watermelon ＇Xiuli＇ as control. The results showed that the growth of both grafted seedlings and own-root seedlings were significantly decreased. Although the photosynthesis of grafted and own-root seedlings were suppressed under NaCl stress, the performance of the grafted seedlings were superior to that of own-root seedlings in net photosynthetic rate,stomatal conductance,intercellular CO2 concentration,transpiration rate and chlorophyll contents. Besides, the activities of superoxide dismutase （SOD）, peroxidase （POD）, and catalase （CAT） in leaves of grafted seedlings were significantly higher than those of own-root seedlings. Malondiadehyde （MDA） content in leaves of grafted seedlings was significantly lower than that in own-root seedlings. The results suggested the grafted watermelon seedlings had the well salt tolerance by obtaining higher activities of antioxidative enzymes to scavenge active oxygen specie （ROS） and therefore reducing oxidative damage and keeping higher photosynthetic rate to increase tolerance of NaCI stress in grafted seedling.