Study On The Coupling Effect Of Water And Fertilizer On Apple Under Well-type Water-saving Irrigation

Apple（Malus domestica Borkh）is one of the important fruit trees in the characteristic forest and fruit industry in the Tarim Basin.Apple plantation is a characteristic industry that promotes regional economic development and improves the ecological environment.However,the management of orchards in this area is generally extensive,and still focuses on flood irrigation and"empirical fertilization".This management mode not only causes waste of water resources and deterioration of the soil environment,but also leads to unsatisfactory apple yields and fruit quality.In order to effectively improve the efficiency of water and fertilizer use in regional orchards,optimize the water and fertilizer management system,and promote the demonstration of simplified cultivation of apple orchards that are conducive to mechanized operations under water-saving irrigation conditions,the 13th company of the fifth group of the first agricultural division in the Aksu area of Xinjiang was held from April to September 2020 The apple orchard has carried out an apple water-fertilizer coupling experiment under well-type water-saving irrigation conditions.The experiment set low,medium,and high fertilization levels（F₁,F₂,F₃）and three irrigation levels（W₁,W₂,W₃）,using a completely random design,a total of 9 treatments,with flood irrigation as the control（CK）.Monitoring and exploring the response of soil water movement and leaf transpiration water consumption,leaf photosynthetic characteristics,apple tree growth and yield quality indicators,irrigation water and fertilizer utilization efficiency under well-type water-saving irrigation conditions to water and fertilizers,the results show that:（1）The seasonal change trend of soil water content under different irrigation amounts（W₁,W₂,W₃）under medium fertilizer treatment showed a multi-peak change,and its main peak appeared within 3 days after irrigation.The soil water content between different irrigation treatments showed CK>W₃>W₁>W₂;the vertical change of soil water content of each soil layer is different.As the depth of the soil layer increases,the soil water content first increases and then decreases.The soil water content at 30cm is larger,and the soil water content at 70cm is larger.The amount of water is the smallest.（2）The stem flow rate is different under different irrigation amount under the medium fertilizer treatment,and its value is CK>W₃>W₂>W₁;on the instantaneous scale,the response of stem flow to meteorological factors under different irrigation gradients is different.However,temperature,solar radiation,and water vapor pressure difference have a greater impact on the stem flow;on a daily scale,30-50cm soil moisture is the key soil layer that affects the stem flow,and it is also an important soil layer area for apple nutrient absorption and water and fertilizer management.（3）The diurnal variation curve of photosynthetic parameters Pn,Tr,Gs,WUE is dominated by single peak in June,and bimodal in August,and the overall photosynthetic level of leaves is higher in August.This period（fruit swelling period）This is the critical period when apples need fertilizer and water.The daily average maximum values of Pn,Gs,and WUE generally appear in the treatment of low fertilizer and high water F₁W₃,the minimum value of Tr appears in the treatment of low fertilizer and low water F₁W₁,and the maximum initial fluorescence value F₀ and maximum fluorescence value Fm generally appear in the treatment of high water W₃.Pn,Gs,WUE,F₀,Fm can reflect the water deficit in the orchard during the main growth period（June-August）of apples to a certain extent.（4）The growth of branches,fruit growth and leaf area of apple trees under different water and fertilizer treatments have different responses to water and fertilizer in different growth periods.The growing branches grow fastest in the young fruit stage,and the largest increase occurs in the F₃W₂ treatment;the fruit increase increases the fastest in the early stage of the young fruit,and the largest increase occurs in the F₃W₂ treatment;the growth period of the leaf growth requires water and fertilizer with the growth period Advance and decrease.（5）Under different water and fertilizer treatments,yield,PFP,IWUE,fruit quality and other indicators have different responses to water and fertilizer.The maximum individual fruit weight,yield,and IWUE all appeared in the F₂W₂treatment,and the maximum PFP appeared in the F₁W₃treatment.The effects of irrigation,fertilization,and water and fertilizer coupling factors on the individual fruit weight,yield,IWUE,PFP were expressed as fertilization>irrigation>water and fertilizer coupling;The maximum acid,ascorbic acid,and fruit water content appeared in F₂W₂,F₂W₃,and F₁W₁ treatments respectively.Fertilizer deficiency and proper irrigation are beneficial to increase the total sugar content in the fruit,but are not conducive to the formation of soluble solids in the fruit.High-fertilizer and high-water treatments Can produce the largest soluble solids,but is not conducive to the accumulation of fruit sugar;F₁W₂ treatment is conducive to the increase in the content of calcium,sodium,magnesium,and zinc in the fruit,F₂ treatment is conducive to the accumulation of potassium and copper in the fruit,F₃ treatment has Conducive to the accumulation of iron and manganese elements in the fruit,the effect of fertilization on the mineral elements in the fruit is greater than the coupling factors of irrigation and water and fertilizer.（6）Based on the principal component analysis,the net photosynthetic rate Pn,,SⅡprimary light energy conversion efficiency Fv/Fm,growing branch growth,yield,IWUE,PFP,soluble solids,total sugar,ascorbic acid,and calcium are comprehensively evaluated,and the most The optimal water-fertilizer combination is the middle water fertilizer treatment F₂W₂,that is,the annual fertilization and irrigation are 1800kg/hm²and 6772.56m³/hm² respectively.Binary quadratic regression analysis shows that when the fertilizer rate is 2175kg/hm² and the irrigation rate is 10594.019,10141.510,10462.033,10742.539,12750m³/hm²,the yield,IWUE,PFP,soluble solids,and calcium can reach the maximum.When the fertilization rate is 1425 kg/hm²and the irrigation rate is 12750 m³/hm²,the total sugar and ascorbic acid can reach the maximum value.（7）The integrated management of water and fertilizer for apple orchards in Aksu area under well-type water-saving irrigation can ensure normal growth of apple trees,stable yield and fruit quality,and can save more than 50%of water and save water compared with flood irrigation.More than 40% fat.