不同黄瓜品种幼苗对等渗Mg(NO_3)_2和NaCl胁迫的生理响应

Physiological responses of different cucumber cultivars seedlings to iso-osmotic Mg( NO_3)_2 and NaCl stress

以3个不同类型的黄瓜品种为试材,采用营养液培养方法,研究等渗Mg(NO3)2和Na Cl胁迫对黄瓜幼苗生长、叶片膜脂过氧化、抗氧化酶活性以及渗透调节物质的影响,采用隶属函数法对其耐盐性进行综合评价.结果表明:与对照相比,60、80 mmol·L-1Mg(NO3)2和等渗90、120 mmol·L-1Na Cl胁迫下,随盐浓度的增加,3种不同生态类型的黄瓜品种幼苗株高、茎粗、叶面积、地上部和地下部干鲜质量及抗氧化酶活性显著降低,盐浓度越高,受抑制程度越高,丙二醛含量显著升高、增幅变大,膜脂过氧化程度加重,其中‘SJ31-1’的生物量及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性下降幅度及丙二醛含量上升幅度均小于其他品种.等渗浓度的Mg(NO3)2比Na Cl对黄瓜幼苗的抑制程度大,浓度越大差异越显著.脯氨酸、可溶性蛋白和可溶性糖含量变化存在基因型和盐类型的差异.盐胁迫后,‘SJ31-1’的脯氨酸含量增幅最大,‘鲁白19号’的可溶性糖含量增幅最大,‘新泰密刺’介于两者之间.Na Cl胁迫下,不同黄瓜品种渗透调节物质以可溶性糖和可溶性蛋白为主,而Mg(NO3)2胁迫下以脯氨酸和可溶性蛋白为主.不同黄瓜品种耐盐性的综合评价次序为‘SJ31-1’>‘新泰密刺’>‘鲁白19号’.

In this study, the effects of iso-osmotic solution of Mg （NO3 ）2 and NaC1 on seedling growth, leaf lipid peroxidation, antioxidant enzyme activities, and osmotic adjustment substance ac- cumulation were investigated using three cucumber cuhivars with different ecotypes. Then salt toler- ance was evaluated by membership function method. The results revealed that under the stress of 60 and 80 mmol · L-1 Mg（ NO3 ）2 solution and its isotonic 90 and 120 mmol ~ L-1 NaC1 solution, the seedling traits such as height, stem diameter, leaf area, fresh and dry mass of aerial part and un- derground parts, and antioxidant enzymes activity were obviously decreased with the increasing con- centration of Mg（ NO3 ）2 and its isotonic NaC1 in the three cucumber cultivars. Moreover, the inhibi- tory effects became more obvious with the increasing concentration of either Mg（ NO3 ） 2 or NaC1 so- lution. MDA content and membrane lipid peroxidation were enhanced in cucumber seedlings. Among the three cuhivars, SJ31-1 changed less than the other two cultivars regarding the reduced ampli- tudes of biomass, and activity of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT）, and the increased amplitude of MDA. In addition, Mg（ NO3 ）2 solution inhibited seedling growth more strongly than isotonic NaC1 solution did, such difference was relatively significant with increasing the concentration of solution. The contents of proline, soluble amino acids, and soluble sugars varied depending on the cucumber genotype and salt type. The increased amplitude of proline content was the largest in SJ31-1, and that of soluble sugars was the largest in Lubai 19 when grow- ing under salt treatment. The change of these parameters in Xintaimici was in between. Soluble sug- ars and soluble proteins were predominant osmolytes unde NaC1 stress, whereas proline and soluble proteins were main osmolytes under Mg （NOa ）2 stress. Comprehensive evaluation showed that salt tolerance of the three cucumber cultivars was in order of SJ31-1 〉 Xintaimici 〉 Lubai 19.