外源水杨酸对淹水胁迫下西瓜幼苗光合特性及抗氧化酶系统的影响

Exogenous salicylic acid affects photosynthetic properties and antioxidant protective enzyme system of watermelon seedlings under waterlogging stress

以‘雪龙1号’西瓜品种为材料,采用不同浓度(0.0、0.5、1.0、1.5、2.5、3.5 mmol/L)水杨酸(SA)溶液喷施幼苗叶片,测定淹水胁迫下西瓜幼苗的生长性状、根系构型、光合参数、叶绿素含量、SPⅡ光能转换效率和抗氧化酶活性等指标,结合主成分分析,研究水杨酸处理对淹水胁迫下西瓜幼苗生理特性的影响。结果表明:喷施SA溶液缓解了淹水胁迫对西瓜幼苗的不利影响,提高了淹水胁迫下西瓜幼苗的叶绿素含量、类胡萝卜素含量、实际光化学效率PSⅡ和超氧化物歧化酶、过氧化氢酶、过氧化物酶活性,降低了植株的丙二醛(MDA)含量,提高了植株耐涝性;与0.0mmol/L的SA处理相比,1.0mmol/LSA处理的西瓜幼苗的株高、茎粗、鲜质量、干质量分别显著提高18.80%、34.74%、23.57%、67.27%;总根长、根尖数分别显著提高116.41%、101.25%;叶绿素a、叶绿素a+叶绿素b、类胡萝卜素含量分别提升了66.55%、67.46%、73.81%;CAT活性显著提高20.92%,MDA含量显著下降53.32%;主成分分析结果表明,1.0、1.5、2.5、0.5、3.5、0.0 mmol/L SA处理的西瓜的耐涝性依次降低。

To investigate the regulatory effect of salicylic acid(SA)on the growth of watermelon seedlings under flooding stress,the‘Xuelong 1’watermelon variety was used as material.Six concentrations(0.0,0.5,1.0,1.5,2.5,3.5 mmol/L)of SA solution were sprayed,and the growth of watermelon seedlings,root system configuration,photosynthetic parameters,chlorophyll content,SPII light energy conversion efficiency,antioxidant enzyme activity and other indicators under flooding stress were measured and then were subjected to the principal component analysist analyze the effects of SA treatment on the physiological characteristics of watermelon seedlings under flooding stress.The results showed that different concentrations of SA alleviated the adverse effects of flooding stress on watermelon seedlings,and increased the activities of chlorophyll content,carotenoid content,actual photochemical efficiency of PSⅡ,superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and decreased the MDA content,of watermelon seedlings under flooding stress.It could be concluded that exogenous SA could improve the flooding tolerance of watermelon seedlings.Compared with 0.0 mmol/L SA treatment,under 1.0 mmol/L SA treatment the plant height,stem thickness,fresh mass and dry mass of watermelon seedlings were significantly increased by 18.80%,34.74%,23.57%and 67.27%,respectively;the total root length and the number of root tips were significantly increased by 116.41%and 101.25%,respectively;and the content of chlorophyll a,chlorophyll a+chlorophyll b and carotenoids were increased by 66.55%,67.46%and 73.81%,respectively;CAT activity increased significantly by 20.92%and MDA content decreased significantly by 53.32%.The results of principal component analysis showed that waterlogging tolerance of watermelons treated with 1.0,1.5,2.5,0.5,3.5 and 0.0 mmol/L SA decreased successively.