Effects Of Irrigation Amount On Yield,Water Use Efficiency And Quality Of Several Crops Based On Meta Analysis

Water resources is one of the most important natural resources on the earth.With the population growth,climate change,rapid economic development and the change of people’s diet structure,the demand for water is increasing,and the global water shortage is becoming more and more serious.Irrigation is an important farmland management measure to increase crop yield and enhance crop adaptability to climate change.However,unreasonable agricultural irrigation has caused a lot of waste of water resources in production practice,aggravated the contradiction between supply and demand of water resources,and had a serious impact on food and social security.With the changes of crop varieties,management measures,climate,soil physical and chemical properties and other factors,there are obvious regional differences in the effects of irrigation on crop yield,water use efficiency and quality,but the impact on the global scale is still unclear.In this study,data from 4763 global distributions were collected and Meta analysis was used to analyze the effects of deficit irrigation(≤ 0.4I,0.6I,0.8I),excessive irrigation(≥ 1.2I)and full irrigation(= 1.0I)on the yield,water use efficiency and quality of several food crops(corn,wheat,soybean and potato),cotton and vegetable crops(tomato,cucumber,pepper,eggplant,melon,watermelon and onion).At the same time,we quantified the effects of different irrigation levels(deficit irrigation,excessive irrigation and complete irrigation)on crop yield under different soil types.The main results are as follows:1)Compared with full irrigation(control,CK),deficit irrigation(≤ 0.4I,0.6I and0.8I)significantly reduces the yield of grain,cotton and vegetables,and the order of yield reduction is(≤ 0.4I)> 0.6I > 0.8I,showing that the more serious the water shortage,the lower the crop yield.Excessive irrigation(≥1.2I)significantly reduces the yield of cotton and vegetables.There is no significant difference in the effects of deficit irrigation on crop yields under different soil types,but deficit irrigation reduces the grain yield of food crops in sandy soil by 54%,indicating that the worse the water holding capacity of the soil(the more serious the water loss),and the more the grain production will be reduced;2)Compared with full irrigation(control,CK),deficit irrigation(≤ 0.4I,0.6I,and0.8I)significantly reduces the single fruit weight of food and vegetable crops,and the less irrigation water,the smaller the single fruit weight.For cotton crops,only ≤ 0.4I treatment significantly reduces the single fruit weight.Excessive irrigation(≥1.2I)doea not significantly change the single fruit weight of vegetables,but it reduced the single fruit weight of cotton;3)Compared with full irrigation(control,CK),deficit irrigation(≤ 0.4I,0.6I,and0.8I)significantly improves the water use efficiency of grain,cotton and vegetables,and the order of the water use efficiency is(≤ 0.4I)> 0.6I > 0.8I,indicating that the less irrigation water,the higher the water use efficiency of crops.Excessive irrigation(≥1.2I)significantly reduces the water use efficiency of cotton and vegetable,indicating that Excessive irrigation may cause water waste.4)Deficit irrigation(≤ 0.4I,0.6I,and 0.8I)significantly reduces the protein and oil production(t/ha)of grain,and the less irrigation water,the lower the protein and oil production.However,deficit irrigation increases the protein content(%)of grain,increases the soluble solids,soluble sugar and Vitamin C of vegetables,indicating that deficit irrigation improves the quality of grain and vegetables.However,deficit irrigation increases the fiber fineness of cotton and weakened the fiber strength of cotton.It shows that deficit irrigation has different effects on the quality of different crops.In specific farming,different irrigation water treatments should be considered according to crop varieties and requirements for yield and quality.This study demonstrates the effects of different irrigation levels on crop yield,water use efficiency and quality,which is of great significance for ensuring food security,optimizing the use of water resources and promoting the sustainable development of agriculture and environment.