Effects Of Water-retaining Fertilizer And Exogenous Melatonin On The Yield,Quality And Water Use Efficiency Of Grape

Grape(Vitis vinifera L.),as an important economic fruit tree,is widely populared by consumers and growers,and planted in the northwest China.The northwest region belongs to the arid and semi-arid areas in the traditional sense,with large evaporation and low rainfall,and is facing the problem of agricultural water shortage.In the local area,the shortage of agricultural water and the unreasonable irrigation system have become important factors restricting the development of the grape industry,and grapevine requires a lot of water.Therefore,it is imperative to improve the water use efficiency and promote the development of the grape industry in the direction of water saving and high efficiency.In this study,’Shine Muscat’ grapes were used as materials under protected culture.Moderate drought stress was applied during the grape coloring and ripening period,and water-retaining fertilizers and exogenous 100 μM melatonin were used respectively,and adequate water supply and no treatment were used as controls.To provide suggestions and references for water-saving and efficient production of grapes,determine the physiological indicators and yield quality of grapes,and explore the effects of water-retaining fertilizers and exogenous melatonin on the water utilization rate of grapes.The main results are as follows:1.During the ripening period of the grapes,the growth of the grapes slowed down.The transverse diameter of the main vine,the length of the internodes,and the growth of the mature functional leaves decreased.Compared with adequate water supply,moderate drought stress at veraison maturity did not have a greater impact on grape growth.There was no significant difference in growth among the groups.2.Long-term drought stress led to the increase of cell membrane permeability,the decrease of relative water content in leaves and chlorophyll accumulation.After using water-retaining fertilizer and melatonin,the decrease of relative water content of leaves slowed down,the damage degree of cell membrane reduced,and the accumulation rate of chlorophyll increased,and the improvement degree of water-retaining fertilizer was higher than that of melatonin.3.Under drought stress,the photosynthetic capacity of leaves decreased.From the beginning to the end of drought stress,the net photosynthetic rate,transpiration rate,and stomatal conductance all decreased.The application of water-retaining fertilizer and melatonin improved the photosynthetic capacity under drought stress,and the improvement degree of water-retaining fertilizer treatment was higher than that of melatonin treatment.,the difference is not significant.At the end of drought stress,the instantaneous water use efficiency of leaves under drought stress decreased significantly,and the water-retaining fertilizer treatment improved the instantaneous water use efficiency of leaves.4.Moderate drought stress at the veraison maturity stage improved grape fruit quality and decreased fruit yield.Under drought stress,the size and weight of grape fruit and ear were decreased,the water content of the fruit decreased,the content of soluble solids and soluble sugar increased,the content of titratable acid decreased,the content of vitamin C and soluble protein increased significantly,and the content of anthocyanins,total The content of phenol and flavonoid increased slightly,but not significantly.The use of water-retaining fertilizers and melatonin alleviated yield losses under drought stress,and fruit quality improved to a certain extent relative to adequate water conditions.5.The use of water-retaining fertilizers and melatonin improved the water use efficiency at the yield level,and the water-retaining fertilizers improved the water use efficiency to a higher degree than melatonin.Through the comprehensive evaluation of fuzzy mathematics membership function,it is concluded that the comprehensive effect of using water-retaining fertilizer is the best among the groups.In conclusion,moderate drought stress during the coloring and ripening period can reduce the fruit yield and water use efficiency,and improve the fruit quality.The use of water-retaining fertilizer and melatonin reduce yield loss under drought stress,maintain the fruit quality,and improve water use efficiency.The comprehensive evaluation of water-retaining fertilizer is better,and it is more instructive for production.