亚低温条件下外源褪黑素和Ca2+对西瓜幼苗生理特性的影响

以西瓜品种8424种子和幼苗为试材,利用人工气候室进行亚低温处理(昼/夜18℃/12℃)20 d,研究外源褪黑素(MT)和Ca²⁺浸种处理对亚低温条件下西瓜种子萌发,西瓜幼苗抗氧化酶SOD、POD和CAT等活性,渗透调节物质可溶性糖和脯氨酸含量的影响。结果表明,亚低温处理的西瓜种子发芽率和发芽势仅为46.5%和40.5%,外源100μmol·L^-1褪黑素和5 mmol·L^-1Ca²⁺复合浸种处理西瓜种子发芽率和发芽势分别达到62.3%和58.5%。外源褪黑素和Ca²⁺浸种处理显著提高了抗氧化酶SOD、POD、CAT和APX活性,促进了渗透调节物质可溶性糖和脯氨酸的积累,有效缓解亚低温对西瓜种子萌发和幼苗生长影响;褪黑素和Ca²⁺复合浸种西瓜幼苗在出苗第20天时植株鲜质量达到8.21 g·株^-1,达到对照处理的85.5%。综上,外源褪黑素和Ca²⁺能通过提高西瓜幼苗抗氧化酶活性和渗透调节能力等,缓解亚低温的不良影响,促进西瓜幼苗生长。

Effects of exogenous melatonin and Ca;on physiological characteristics of watermelon seedlings under sub-low temperature

The seeds and seedlings of watermelon cultivar 8424 were treated with sub-low temperature(day/night 18℃/12℃)for 20 days in an artificial climate chamber to study the effects of exogenous melatonin(MT)and Ca²⁺ on germination,activities of antioxidant enzymes(SOD,POD and CAT),and contents of soluble sugar and proline.The results showed that the germination rate and germination potential of watermelon seeds treated with sub-low temperature were only 46.5%and 40.5%,and those treated with 100μmol·L^-1 melatonin and 5 mmol·L^-1 Ca²⁺ were 62.3%and 58.5%,respectively.Exogenous melatonin and Ca²⁺ treatment significantly increased the activities of antioxidant enzymes(SOD,POD,CAT and APX),promoted the accumulation of osmotic adjustment substances(soluble sugar and proline),and effectively alleviated the effect of sub-low temperature on watermelon seed germination and seedling growth.The seedling fresh weight treated with melatonin and Ca²⁺reached 8.21 g·plant^-1 on the 20th day of emergence,which was 85.5%of the control.