外源褪黑素对盐胁迫下念珠刺桐幼苗生理特性的缓解效应

Alleviating Effect of Exogenous Melatonin on Erythrina tholloniana Seedlings under Salt Stress

为探讨褪黑素对盐胁迫下念珠刺桐生理机制的影响,以念珠刺桐幼苗为材料,进行盐胁迫(100 mmol/L NaCl)下叶片喷施外源褪黑素(0,50,100,150,200μmol/L)处理,研究外源褪黑素对盐胁迫下念珠刺桐生长、光合效率及抗氧化作用的影响.结果表明,盐胁迫会显著抑制念珠刺桐的生长,降低渗透调节和抗氧化能力,以及光合作用.而在盐胁迫下通过叶片喷施100μmol/L褪黑素能够显著促进植株生长,提高可溶性糖和可溶性蛋白含量,减少电解质外渗,降低丙二醛含量,促进叶片中SOD、POD、CAT和APX活性的提高;提高叶绿素和类胡萝卜素含量,促进光合效率的提高;但高浓度(150,200μmol/L)外源褪黑素反而会产生一定程度的氧化胁迫和渗透胁迫.因此,100μmol/L外源褪黑素处理能较好地缓解盐胁迫下念珠刺桐的渗透胁迫、氧化胁迫和光合效能,有利于促进念珠刺桐生长.

To explore the effect of exogenous melatonin on the physiological mechanism of Erythrina tholloniana seedlings under salt stress.Using Erythrina tholloniana seedlings as materials,exogenous melatonin(0,50,100,150,200μmol/L)was sprayed on the leaves under salt stress(100 mmol/L NaCl)to study the effects of exogenous melatonin on the growth,photosynthetic efficiency,and antioxidant activity of Erythrina tholloniana seedlings under salt stress.The results showed that salt stress significantly inhibited the growth of Erythrina seedlings,reduced osmotic regulation,antioxidant capacity,and photosynthetic efficiency.Under salt stress,spraying 100μmol/L melatonin on leaves can significantly promote plant growth,increase the content of soluble sugar and protein,reduce electrolyte leakage rate,decrease malondialdehyde content,and promote the increase of activities of superoxide dismutase(SOD)and peroxidase(POD)and catalase(CAT)and ascorbic acid peroxidase(APX)in leaves;increasing the content of chlorophyll and carotenoids can promote the improvement of photosynthetic efficiency.However,high concentrations of exogenousmelatonin(150,200μmol/L)actually lead to a certain degree of oxidative and osmotic stress.Therefore,100μmol/L exogenous melatonin can effectively alleviate the osmotic stress,oxidative stress,and photosynthetic efficiency of Erythrina tholloniana seedlings under salt stress,which is beneficial for promoting the growth of Erythrina tholloniana seedlings.