Effects Of Micronized Chitosan Loaded With Melatonin On Stress Resistance Of Wheat Seedlings

There are many abiotic stresses in wheat seedling growth,among which drought and salt stress are especially common.Drought will inhibit the growth of wheat before winter and cause insufficient tillering,making it difficult to lay a good foundation for high yield in the laterperiod.Salt stress not only causes plant mineral nutrient deficiency,but also leads to plant death.Adding exogenous melatonin can improve plant resistance to abiotic stress,regulate water balance,maintain leaf and chloroplast integrity,and regulate nitroxidation homeostasis and proline metabolism.However,there are still problems such as unclear dosage of melatonin in wheat resistance to abiotic stress and low agricultural utilization rate.Therefore,it is of practical significance to screen the optimal concentration of melatonin applied at the seedling stage of wheat to realize the efficient utilization of melatonin.In this study,by applying a series of different concentrations of melatonin to wheat seedlings under drought and salt stress,the optimal concentration of melatonin to relieve stress in wheat seedlings was screened,and the stress resistance mechanism of melatonin on wheat seedlings was discussed.On the basis of the test of melatonin enhancing wheat stress resistance,the melatonin was loaded with chitosan particles and applied to the experimental study of drought stress at the seedling stage of wheat to realize the efficient utilization of melatonin,in order to provide melatonin Provide theoretical and technical support in agricultural extension.The main findings are as follows:（1）Root application of 300umol L-1 melatonin significantly enhanced drought resistance of wheat.Compared with the drought control,300umol L-1 melatonin significantly increased wheat germination rate and dry weight by 31.25%and 65.38%,chlorophyll a content by50.51%,root length by 97.79%,and SOD activity by 45.64%,enhanced the activity of antioxidant enzymes,reduced the degree of membrane lipid peroxidation,and promoted the growth of wheat at the seedling stage.（2）Root application of 300umol L-1 melatonin significantly alleviated salt stress injury.Compared with the salt stress control,the germination rate of wheat seeds treated with melatonin at a concentration of 300umol L^-1was significantly increased by 19.41%,the biomass of the whole wheat seedlings was significantly increased by 65.38%,and the chlorophyll content was significantly increased by 41.77%;the root length was significantly increased.The increase of 121.10%,the SOD activity increased significantly by 77.73%,the antioxidant enzyme activity of wheat seedlings was improved,and the damage of salt stress to wheat was alleviated.（3）The melatonin chitosan particles prepared by the ion gel method realize the slow release of melatonin and improve the utilization rate of melatonin under stress.The simulated release test of melatonin-chitosan particles showed that the release rate of MP-MT was65.43%in phosphate buffer solution with p H 5.0 for 36 h.Compared with MT1.0 treatment,MP-MT0.5 treatment significantly increased wheat dry weight by 22.36%,root length by16.03%,and peroxidase activity by 15.65%.In summary,this study screened out the optimal application concentration of melatonin under drought and salt stress in wheat,explored the physiological and biochemical mechanism of melatonin in improving wheat stress resistance,and solved the problem of melatonin’s existence.Oxidation,photodegradation and other problems provide a solution,and provide theoretical and data support for the popularization and application of melatonin.