Effects Of Exogenous Putrescine On Drought Resistance Physiology Of Grape Seedling Leaves Under Drought Stress

Drought is one of the most important abiotic stresses in grape growth and development,which will seriously affect the quality and yield of grapes.Putrescine（Put）plays an important role in the adaptation of plants to stress,and it has the functions of removing active oxygen in plants,protecting plasma membrane and stabilizing biological macromolecules.However,the effect of Put on the mitigation effect of wine grapes under drought stress still needs further research.This experiment mainly studied the effects of exogenous Put treatment on the relevant drought resistance indexes of Cabernet Sauvignon grape seedlings under drought stress.In this study,Cabernet Sauvignon were treated with three concentrations（0.01,0.10,1.00 mmol/L）and sterile water control.The main research contents include the effects of spraying exogenous putrescine on photosynthesis index,active oxygen content,carbohydrate and antioxidant system of Cabernet Sauvignon seedlings under drought stress.The main findings are as follows:（1）Compared with the control,the concentration of 0.01 mmol/L and 0.10 mmol/L Put can significantly increased the the net photosynthetic rate（Pn）,stomatal conductance（Gs）and transpiration rate（Tr）of grape leaves,and 1.00 mmol/L had no significant difference with the control.Three concentrations of exogenous Put can significantly reduce the accumulation of hydrogen peroxide（H₂O₂）,superoxide anion（O₂.^-）and malondialdehyde（MDA）in the leaves,and reduce the relative conductivity of the leaves,of which 0.01mmol/L and the difference between 0.10mmol/L concentration treatment and control was significant,and the increase of 0.10mmol/L was larger.（2）Put at concentrations of 0.01 mmol/L and 0.10 mmol/L could significantly increase the accumulation of soluble sugar,fructose,sucrose and soluble starch in grape leaves at the late stage of drought stress.There was no significant difference between 1.00mmol/L treatment and control..（3）Three concentrations of Put treatment can increase superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）,ascorbate peroxidase（APX）,and single Hydrogen ascorbate reductase（MDHAR）,dehydroascorbate reductase（DHAR）and glutathione reductase（GR）,as well as ascorbic acid（As A）and reduced glutathione（GSH）,of which0.01 mmol/L Put increased significantly and was significantly different from the control.In summary,0.01 and 0.10mmol/L Put can significantly alleviated the damage of Cabernet Sauvignon seedlings under drought stress,enhanced photosynthesis ability and carbohydrate accumulation,reduced the accumulation of reactive oxygen species under adverse conditions,and protected cell membrane from Damage,improved the efficiency of the operation between antioxidant enzymes and antioxidants,and improved the drought tolerance of Cabernet Sauvignon.