[目的]探究外源褪黑素(melatonin，MT)对盐胁迫下棉花生长发育的调控效应。[方法]以国欣棉9号为材料，采用室内盆栽方法，土壤含盐量为0。3％(质量分数)，筛选出适宜的MT浓度后，设置4个处理:浇灌清水+喷施清水(CK)、浇灌盐水+喷施清水(S)、浇灌清水+喷施MT(MT)和浇灌盐水+喷施MT(MS)，研究了不同处理下棉花的株高、茎粗、叶面积、叶绿素相对含量(用soil and plant analyzer development，SPAD值代表)、单株生物量、根冠比、抗氧化酶活性、活性氧含量以及渗透调节物质含量的变化，并对上述指标进行了相关分析。[结果]与CK处理相比，S处理显著降低棉花的株高、茎粗、叶面积、SPAD值、单株地上部鲜物质质量、地下部鲜物质质量、地上部干物质质量、地下部干物质质量，显著提高根冠比;在盐胁迫处理后期，S处理显著降低叶片超氧化物歧化酶(superoxide dismutase，SOD)、过氧化物酶(peroxidase，POD)和过氧化氢酶(catalase，CAT)活性，显著提高过氧化氢、超氧阴离子和丙二醛的含量，显著降低可溶性糖、可溶性蛋白和脯氨酸的含量。与S处理相比，盐胁迫下叶片喷施200p-mol-L-1 MT(MS处理)可显著提高棉花的株高、茎粗、叶面积、SPAD值、单株地上部与地下部的鲜物质质量及地上部干物质质量，显著降低根冠比，显著提高SOD、POD和CAT活性，显著降低过氧化氢、超氧阴离子和丙二醛的含量，显著提高可溶性糖、可溶性蛋白和脯氨酸的含量。棉株地上部干物质质量与株高、茎粗、叶面积、SPAD值、地上部鲜物质质量、地下部鲜/干物质质量、SOD活性、POD活性、CAT活性、可溶性糖含量、可溶性蛋白含量、脯氨酸含量均呈显著正相关关系，而与超氧阴离子含量、丙二醛含量显著负相关。[结论]叶面喷施200 μmol·L-1 MT能够有效缓解高盐环境(土壤含盐量为0。3％)对棉花产生的氧化胁迫与渗透胁迫，促进棉花生长，提高耐盐能力。
Effects of exogenous melatonin on the growth and development,antioxidant enzyme activity,and osmotic adjustment substance content of cotton under salt stress
[Objective]This study aims to investigate the regulatory effect of exogenous melatonin(MT)on cotton growth and development under salt stress.[Methods]Guoxinmian 9 was used as the material,and the indoor pot method was adopted with the soil salt content of 0.3％,and after screening out the appropriate MT concentration,four treatments were set:irrigate water+spray water(CK),irrigate salt water+spray water(S),irrigate water+spray MT(MT),and irrigate salt water+spray MT(MS).The plant height,stem diameter,leaf area,relative chlorophyll content(soil and plant analyzer development,SPAD value),biomass per plant,root-shoot ratio,antioxidant enzyme activity,reactive oxygen species content,and osmotic adjustment substance content of cotton under different treatments were studied.And correlation analysis of the above indexes was carried out.[Results]Compared with CK treatment,S treatment significantly reduced plant height,stem diameter,leaf area,SPAD value,aboveground fresh matter mass,underground fresh matter mass,aboveground dry matter mass,and underground dry matter mass,and significantly increased root-shoot ratio of cotton.In the later stage of salt stress treatment,S treatment significantly reduced the activities of superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)in cotton leaf;significantly increased the contents of hydrogen peroxide,superoxide anion,and malondialdehyde;and significantly decreased the contents of soluble sugar,soluble protein,and proline.Compared with S treatment,foliar spraying 200 µmol·L-1 MT under salt stress(MS treatment)significantly increased plant height,stem diameter,leaf area,SPAD value,aboveground and underground fresh matter mass,and aboveground dry matter mass per plant;significantly reduced root-shoot ratio;significantly increased SOD,POD,and CAT activities;significantly reduced the contents of hydrogen peroxide,superoxide anion,and malondialdehyde;and significantly increased the contents of soluble sugar,soluble protein,and proline.Aboveground dry matter mass was significantly and positively correlated with plant height,stem diameter,leaf area,SPAD value,aboveground fresh matter mass,underground fresh and dry matter mass,SOD activity,POD activity,CAT activity,soluble sugar content,soluble protein content,and proline content;while was significantly and negatively correlated with superoxide anion content and malondialdehyde content.[Conclusion]Foliar spray 200 µmol·L-1 MT can effectively alleviate the oxidative stress and osmotic stress of cotton under high salt environment(soil salt content of 0.3％),promote cotton growth,and improve salt tolerance of cotton.
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