外源钙对NaCl胁迫下西瓜幼苗生长的缓解效应研究

目的]阐明外源钙对NaCl胁迫下西瓜幼苗生长的缓解效应.方法]在向培养西瓜幼苗的营养液中添加100 mmol/L NaCl模拟盐胁迫的同时,添加CaSO4使Ca2+浓度分别达到4、6、10和14 mmol/L.处理10天后对西瓜幼苗的生长和生理指标进行测定,包括株高、茎粗、单株叶片数、植株最大叶的叶长和叶宽、鲜重、干重、丙二醛(MDA)含量、质膜相对透性、抗坏血酸(AsA)含量、游离脯氨酸含量、可溶性糖含量和可溶性蛋白含量等.结果]100 mmol/L NaCl胁迫显著抑制了西瓜幼苗的生长,使叶片质膜透性、MDA含量显著增加,脯氨酸、可溶性糖、可溶性蛋白和抗坏血酸含量也不同程度增加;外源CaSO4可影响NaCl胁迫下幼苗的生长和生理指标,并有明显的浓度效应,其中6 mmol/L Ca2+处理显著促进了NaCl胁迫下幼苗的生长,使叶片质膜透性、MDA含量显著降低,脯氨酸、可溶性糖、可溶性蛋白和抗坏血酸含量显著增加.结论]外源CaSO4可通过增强抗氧化能力和渗透调节能力,减轻胁迫造成的膜脂过氧化伤害,缓解NaCl胁迫对西瓜幼苗生长的抑制,且以6 mmol/L Ca2+处理的缓解效果最好.

Effects of Exogenous Calcium (Ca) on the Growth of Watermelon Seedlings under NaCl Stress

Objective] This study was conducted to reveal the effect of exogenous calcium (Ca) in mitigating the damage caused by NaCl stress to watermelon seedlings. Method] To the liquid medium containing 100 mmol/L NaCl, CaSO4 was added to the final concentrations of 4, 6, 10 and 14 mmol/L. The morphological and physiological indices including plant height, stem diameter, number of leaves per plant, maximum leaf length, maximum leaf width, seedling fresh weight and dry weight, malondialdehyde (MDA) content, relative permeability of plasma membrane,ascorbic acid (AsA) content, free proline content, soluble sugar content and soluble protein content in leaves of the seedlings treated with above media for 10 d were measured. Result] NaCl stress significantly inhibited the growth of watermelon seedlings. The membrane permeability and MDA content in leaves were significantly increased under NaCl stress, and the contents of proline, soluble sugar, soluble protein and AsA were increased to different extents. Exogenous CaSO4 influenced the morphological and physiological indices of seedlings under NaCl stress in a concentration-dependent manner. Treated with 6 mmol/L CaSO4, the growth of seedlings under salinity was significantly improved; membrane permeability and MDA content were drastically reduced, the contents of proline, soluble sugar, soluble protein and AsA in leaves were significantly increased. Conclusion] Exogenous CaSO4 alleviates lipid peroxidation and inhibition of seedling growth under NaCl stress by improving the abilities of antioxidation and osmotic adjustment, and 6 mmol/L CaSO4 showed the best effect.