外源褪黑素对高温胁迫下厚皮甜瓜幼苗光合及抗氧化特性的影响

Effects of exogenous melatonin on photosynthesis and antioxidant activities of muskmelon seedlings under high temperature stress

以厚皮甜瓜‘迎春’杂交种为试材,采用营养钵种植法,设5种不同浓度(50、100、150、200和250μmol/L)的褪黑素(MT)溶液,以清水为对照,经MT溶液处理后对幼苗进行高温胁迫(昼43±1℃/夜32±1℃)4d。通过测定幼苗叶片光合参数及SOD、POD和CAT等生理生化指标,研究外源MT溶液对高温胁迫下幼苗叶片光合作用及抗氧化特性的影响。结果显示:高温胁迫下喷施不同浓度MT溶液,可不同程度地提高厚皮甜瓜幼苗叶片中光合色素含量、光合能力及抗氧化酶活性,与对照相比,200μmol/LMT处理时,厚皮甜瓜幼苗叶片中叶绿素含量和净光合速率达到最高峰,分别为4.43、8.87μmol/(m^2·s);SOD、POD和CAT活性也达到最大,分别为211.28、24.77和376.92U/g;且MDA含量降到最低,为7.93μmol/g。结果表明,高温胁迫下外源MT能增强厚皮甜瓜幼苗抵抗力,且浓度为200μmol/L时效果最佳。

The hybrid of muskmelon‘Yingchun’was used as the test material,and planted in the nutritious pots for the research.Five different concentrations(50,100,150,200 and 250μmol/L)were set up to prepare the melatonin(MT)solution.With clear water as the control,the seedlings were treated with MT solution for 4 days under high temperature stress(day 43±1℃/night 32±1℃).The effects of exogenous MT solution on photosynthesis and antioxidant properties of seedling leaves under high temperature stress were studied by measuring photosynthesis parameters and physiological and biochemical indices such as SOD,POD and CAT.The results showed that spraying different concentrations of MT solution under high temperature stress could increase photosynthetic pigment content,photosynthetic capacity and antioxidant enzyme activity in leaves of muskmelon seedlings in different degrees.Compared with the control,when treated with 200μmol/L MT,The chlorophyll content and net photosynthetic rate of muskmelon seedlings reached the highest peaks,which were 4.43 mg/g and 8.87μmol/(m^2·s),respectively.The activities of SOD,POD and CAT also reached the maximum,which were 211.28,24.77,and 376.92 U/g respectively;and the MDA content was minimized to 7.93μmol/g.The results showed that exogenous MT could enhance the resistance of muskmelon seedlings under high temperature stress,and the best effect was at the concentration of 200μmol/L.