Journal of Peanut Science

In order to explore the alleviation effects of exogenous melatonin(MT) on the growth of peanut seedlings and their roots under different salt concentration stress,the peanut cultivar Shanhua9 was taken as the test material,and five treatments were set up by nutrient solution culture method:CK(1/2 Hoagland nutrient solution);T1(1/2 Hoagland nutrient solution+150 mmol/L NaCl);T2(1/2 Hoagland nutrient solution+200 mmol/L NaCl);T3(1/2 Hoagland nutrient solution+ 150 mmol/L NaCl+15 μmol/L MT);T4(1/2 Hoagland nutrient solution+ 200 mmol/L NaCl+15 μmol/L MT).The growth,root activity,photosynthetic pigments,antioxidant system,osmotic adjustment substances and electrical conductivity of seedlings under different treatments were determined,and the correlation analysis between seedling growth and physiological indices was conducted to study the effects of exogenous MT on the growth and physiological characteristics of peanut seedlings under salt stress.The results showed that the application of exogenous MT significantly improved the growth and physiological indices of peanut seedlings under salt stress and effectively relieved the inhibitory effect of salt stress on peanut seedling growth.Among which, the MT exhibited stronger alleviating effect under high salt stress:Compared with T2,the plant height increased by 10.7%,fresh mass increased by 11.4%,root activity increased by 27.85%,chlorophyll a content increased by 19.58%.SOD activity increased by 21.97 %,while hydrogen peroxide content decreased by 17.13 % and the soluble protein content increased by 28.01% under T4 treatment.In conclusion,the exogenous MT can enhance the salt tolerance of peanut seedlings by increasing the content of photosynthetic pigments to improve photosynthetic performance,regulating the activity of the antioxidant system and reducingthe accumulation of reactive oxygen species to alleviate oxidative stress,and optimizing osmotic adjustment metabolism to relieve osmotic damage.Moreover,the stress alleviating effects of exogenous MT on peanut growth was better under the 200 mmol/L NaCl condition.