Study On Root Distribution And Soil Water Dynamics Of Apple Trees Of Water Storage Pit Irrigation Under Different Irrigation Treatments

With the development of the social economy and the improvement of the people's living standard,the importance of apple in people's lives gradually reveals.Apple is rich in nutrition,and is one of the indispensable food of people's life,as a result,apple has become an important part of the agricultural planting structure in China.However,due to the existence of the drought problem,seriously affects the apple's yield and quality.Water storage pit irrigation is a method to solve the drought problem of north China,this new method is suitable for medium and deep level orchard irrigation.Different irrigation treatments,and the suitable soil moisture were the basis of high yield and high quality of the orchard in water storage pit irrigation.Therefore,the paper adopted the research methods of field experiment,theoretical analysis and simulation,studied on root distribution and soil water dynamics of apple trees under water storage pit irrigation,which set three different irrigation treatments(50-80% of the field capacity,60-90% of field capacity,70-100% of field capacity)in this experiment.The research results indicated:1.Before the irrigation,the distribution of moisture content with different treatment had the similar variation trend,it increased with the increasing soil depth,the values of moisture content with the 3 treatments followed a descending order of W3>W2>W1.After the irrigation,the distribution of moisture content was axiolitic,in which the central axis of water storage pit was taken as the symmetry axis.The more distance between the position and the pit centre was.the lower the moisture content was.Under different water treatment,the distribution range and the value of moisture content was not same,and it followed a descending order of W3>W2>W1.The one-dimensional,two-dimensional,three-dimensional distribution model with different water treatment under water storage pit irrigation was fitted to exponential function.The moisture content treated with the surface irrigation mainly distributed in the surface soil,while that treated with the method of the water storage pit irrigation distributed in the soil with the depth of 30-120 cm.The method of water storage pit irrigation had more advantages of water-saving and water-retention than the surface irrigation.In any soil depth,the moisture content with different treatment had the same changing trend with time,the average values of moisture content with the 3 treatments followed a descending order of W3>W2>W1.The average value of the whole soils showed the jagged changing trend with time over the whole stage,the relative size of the value with the three treatments was shown as W3>W2>W1,and the difference among different treatments had reach the extremely significant level.2.For fruiter water storage pit irrigation,the water requirement and water requirement intensity increased with the increase of irrigation amount in the whole growth period.The water requirement and water requirement intensity's size relation under different treatments were W1 <W2<W3;apple tree's water requirement and crop coefficient of different treatments presented change as parabola-shape with time,crop coefficient's size relation under different treatments was W1<W2<W3;the sap flow of different irrigation treatments gradually increased and then gradually reduced wit time,the sap flow account's size relation under different treatments assumed as: W3>W2>W1;orchard soil evaporation of different irrigation treatments gradually increased and then gradually reduced wit time,soil evaporation proportion for crop water requirement showed an opposite tendency.3.The vertical distribution law of root length density?root surface area density?root weight density? moisture content of fresh root and root activity under different irrigation treatments were in agreement,increases with depth.Distribution range of root length density?root surface area density?root weight density?moisture content of fresh root and root activity were different under different irrigation treatments in different growth stages,the depth distribution range of root length density?root surface area density and moisture content of fresh root was W3>W2>W1,depth range of root weight density was W2>W3>W1,the depth distribution of root activity was different in different growth stages,it assumed as W2>W3>W1 in fast-growing period of shoot and fullbloom stage,the result was W3>W2>W1 in young fruit period?expanding stage and maturity.For different irrigation treatments in different growth stages,the position relation of the vertical maximum of root length density?root surface area density?root weight density?moisture content of fresh root and root activity were W3>W2>W1.We established vertical distribution model spatial and temporal dynamic model,that is about root length density?root surface area density?root weight density?moisture content of fresh root and root activity under different irrigation treatments.The root length density?root surface area density?root weight density?moisture content of fresh root and root activity of water storage pit irrigation W2 were greater than that of surface irrigation DM,root length density?root surface area density?root weight density?root activity of W2 was 1.14,1.15,1.21,1.01 and 1.18 times more than that of surface irrigation DM.4.Different irrigation treatments had significant effects on the yield and quality of apple trees in water storage pit irrigation,the relation among the yield per plant?fruit shape index?brittleness and soluble solid was W3>W2>W1,titratable acid's size relation was W3>W1>W2,sugar acid ratio's size relation was W2>W3>W1.Comprehensive comparison of average root activity?fruit shape index?fruit firmness?soluble solid?titratable acid?sugar acid ratio and water productivity,principal component analysis method was used to draw a comprehensive ranking of different irrigation W2>DM>W1>W3,that is to say,the appropriate irrigation treatment for water storage pit irrigation was W2.5.Based on least squares support vector machine,LSSVM-WSP-1 soil water storage and LSSVM-WSP-10 layered soil moisture prediction model were established,initial soil storage or initial soil moisture?starting time?forecast period length?irrigation amount in period?rainfall in period?reference crop evapotranspiration ET0 and processing number were taken as input,soil water storage or moisture content of 2m thick soil layer in the root zone of water storage pit irrigation orchard were taken as output,accelerating differential evolution algorithm solves super parameter in the model was proposed,and the model was validated by field test data,the results showed that the model has high precision,can be used to prediction of moisture storage and layered soil moisture in water storage pit irrigation.