外源水杨酸对高温胁迫下牡丹幼苗耐热性的影响

Effects of Exogenous Salicylic Acid on Heat Tolerance of Tree Peony Seedlings under High Temperature Stress

为明确外源水杨酸(SA)提高牡丹幼苗耐热性的作用机制,以牡丹品种凤丹(Paeonia ostii Fengdan)幼苗为试材,研究了不同浓度SA对高温胁迫后牡丹幼苗热害指数和叶片电解质渗透率的影响,最适浓度SA对高温胁迫下牡丹幼苗生长和叶片生理指标的影响。结果表明,100.0μmol/L为SA提高牡丹幼苗耐热性的最适浓度。与单纯高温处理相比,100.0μmol/L的SA处理能显著增加牡丹幼苗干质量,降低热害指数、电解质渗透率、丙二醛(MDA)含量;提高超氧化物歧化酶(SOD)活性,显著增加可溶性蛋白含量;在高温胁迫后期(≥4 d),显著增加游离脯氨酸和叶绿素含量。说明外源SA可以通过提高牡丹幼苗抗氧化能力和渗透调节能力来诱导牡丹幼苗耐热性,缓解高温伤害。

To elucidate the mechanism underlying treatment of exogenous salicylic acid(SA)in enhancing heat tolerance of tree peony seedling,Paeonia ostii Fengdan seedlings were used in the study.We studied the effects of SA at different concentrations on heat injury index of the seedlings and leakage rate of electrolyte in the leaves after the seedlings exposed to high temperature,and the effects of SA at optimum concentration on the growth and physiological index of leaves under high temperature stress.The results showed that 100.0μmol/L was the most effective concentration for enhancing heat tolerance of tree peony seedlings.Compared with sole high temperature treatment,the application of 100.0μmol/L SA increased dry weight of seedlings significantly,lowered its heat injury index,leakage rate of electrolyte and malondialdehyde(MDA)content,increased superoxide dismutase(SOD)activity,soluble protein content,chlorophyll content and soluble proline content significantly at the late period of heat treatment(≥4 d).The results suggested that exogenous SA could enhance heat tolerance and relieve high temperature damage of tree peony through improving its ability of antioxidant and osmotic adjustment.