Effects Of Exogenous Melatonin On The Growth And Photosynthetic Characteristics Of Cotton Seedlings Under Salt Stress

In this study,Xinluzhong 70 was used to study the effection of different concentrations of melatonin on cotton seed germination,seedling growth,photosynthetic parameters,and chlorophyll fluorescence parameters of leaves under NaCl stress.Revealing the regulation of exogenous melatonin on cotton seed germination,seedling growth and photosynthetic parameters under NaCl stress.The main findings were as follows:1.The effection of melatonin soaking treatment on the germination of cotton seeds under NaCl stressGermination was significantly inhibited under NaCl stress.Compared with the normal control,the seed germination index,hypocotyl growth and biomass accumulation were significantly reduced.After the melatonin soaking treatment,the germination of cotton seeds was significantly improved and promoted the growth.Hypocotyl growth and dry matter accumulation of seedling indicate that melatonin can strengthen cotton’s ability to resist NaCl stress and increase the salt tolerance of cotton at seedling stage.Alleviate the inhibitory effect of NaCl stress on the root vitality of cotton seedlings.The best melatonin soaked was 25μmol·L^-1.2.The effect of spraying melatonin on the growth and development of seedlings under salt stressUnder NaCl stress,plant height,stem diameter,leaf area,total dry weight,root system and other indicators were significantly decreased,it was increased to promote normal plant growth by spraying melatonin.100μmol·L^-1melatonin was sprayed under NaCl stress treatment can improve the salt tolerance of cotton seedlings and alleviate the damage of NaCl stress to cotton.3.The effect of spraying melatonin on the photosynthetic parameters of cotton leaves under NaCl stressPhotosynthetic rate,chlorophyll content,φPSII,q P,Fv’/Fm’fluorescence parameters and other indicators of cotton seedlings were decreased under NaCl stress.After spraying melatonin,it effectively alleviated the photosynthetic characteristics of cotton seedling leaves.The best melatonin spraied was 100μmol·L^-1.After 9 d of NaCl stress,Pn,Gs,and Ci indicators of cotton seedlings gradually decreased,this showed that 9 days of internal and external melatonin can promote the growth of cotton seedlings.4.The effect of exogenous melatonin on cotton seedlings under salt stress in the fieldSpraying exogenous melatonin can alleviate the inhibitory effect of NaCl stress on the growth of seedlings.By increasing the SPAD and the chlorophyll content of leaves to keep the normal growth.The accumulation of seedling biomass ultimately enhances the ability of cotton seedlings to resist salt damage,and relatively reduces the adverse effects of cotton on the quality and yield of harvest after salt damage at the seedling stage.The best melatonin spraied was 100μmol·L^-1.