Effect Of Irrigation Amount And Frequency On Growth,Yield And Water Use Efficiency Of Apple

In order to explore the systematic characteristics of water demand for the growth and development of dwarfing rootstock close planted apple for improving the use efficiency of limited water resource,this paper conducted a 2-year field experiments in Tang County,Baoding City.Two sets of field experiment with irrigation volume and irrigation frequency were set up.The irrigation volume experiments set five treatments,with traditional irrigation volume as the control(W0),with an increase of 20%(W1),a decrease of 10%(W2),and a decrease of 20%(W3)Reduce by 30%(W4);Five treatments were set up for the irrigation frequency experiment,including 100%traditional irrigation frequency(TW0),120%traditional irrigation frequency(TW1),110%irrigation frequency(TW2),90%irrigation frequency(TW3),and 80%irrigation frequency(TW4).Study the effects of irrigation amount and irrigation frequency on the growth and development,leef and soil nutrients,yield and quality,and water use efficiency of dwarfing rootstocks close planting apple under integrated water and fertilizer conditions,clarify the water demand law of apple trees planted on short rootstocks,and determine the optimal irrigation plan for achieving high yield,quality,and efficiency of apple trees.The main findings of this study are as follows:(1)Under different irrigation amounts,the root dry matter quality and root morphology indicators of the water reducing group showed a trend of first decreasing and then increasing with the water reducing gradient.The water increasing treatment W1 showed no significant difference compared to the traditional treatment.Among them,the W3 treatmentshowed the most sensitive response of apple roots to water deficit,with improved root morphology indicators compared to the traditional treatment W0.The root dry matter mass,total root length,root surface area,volume,and root tip number increased by 14.81%,14.19%,28.53%,16.67%,and 25.49%,respectively.Under different irrigation frequency,the comprehensive performance of root system indicators is as follows:the group with fewer and more irrigation frequency>the traditional irrigation frequency>the group with fewer and fewer irrigation frequency,with TW3 and TW4 having relatively developed root systems.(2)Reducing the amount of single irrigation did not reduce apple yield and quality.On the contrary,reducing water by 10～20%can steadily promote apple quality improvement and yield increase.Under different irrigation amounts,the average annual yield of W1 treatment is the highest,followed by W2 treatment,with values of 27.74 and 27.28 t·hm-2,respectively.The solid acid ratio and Vc content of W3 treatment were the highest,with an increase of 27.35%and 10.02%compared to W0 treatment.However,there was no significant difference in fruit shape index between different irrigation treatments.Under different irrigation times,TW1 treatment had the highest yield,followed by TW3 treatment.The average yield between two years was 34.81 and 34.66 t·hm-2,respectively,with no significant difference between the two treatments.In terms of fruit quality,the fruit shape index,solid acid ratio,and Vc content of TW1 and TW2 treatments showed an increasing trend compared to other treatments,improving the quality and commercial value of apples.(3)Changing the amount and frequency of irrigation is beneficial for fruit trees to transform and absorb soil nutrients,with the nutrient content in the topsoil and subsurface layers being more affected by irrigation.Under different irrigation amounts,the nitrate nitrogen content of W3 and W4 treatments in the 0～20cm soil layer increased by 23.53%～31.97%compared to traditional treatments,respectively.The available phosphorus content of W2 and W3 treatments decreased by 16.48%compared to traditional treatments,and the available potassium content increased by 2.69%～19.19%.Under different irrigation times,the comprehensive performance of soil nutrient indicators is as follows:multiple small amount group>traditional irrigation times>small amount group.Reducing the amount of irrigation did not reduce the nutrient content of the leaves.Mild water deficit actually promoted the absorption and utilization of nutrients by the leaves.Under the experimental conditions of the two irrigation modes,the change trend of each treatment on the nitrogen,phosphorus,and potassium content of the leaves was almost consistent with that of the soil.(4)The water management mode of reducing single irrigation volume by 10～20%and increasing irrigation frequency by 10～20%can both improve soil water storage,reduce water consumption,and improve water use efficiency in orchards.The soil water storage at different stages of apple development shows a "V-shaped"change,reaching its maximum value during the fruit expansion period.Under different irrigation amounts,W3 treatment had the highest soil water storage capacity,while W2 and W3 treatments had higher water use efficiency,which increased by 3.53%～6.24%compared to traditional treatments;Under different irrigation times,the water use efficiency of TW1 treatment was the highest,reaching 64.72 kg·(mm·hm-2)which increased by 4.64%～18.02%compared to other treatments,respectively.In summary,a water management model that reduces single irrigation volume by 10～20%(W2 treatment,irrigation volume:9 mm;W3 treatment,irrigation volume:8 mm)and increases irrigation frequency by 20%(TW1 treatment,irrigation volume:10 times)is more conducive to apple growth and root development,promoting the absorption and transformation of soil nutrients by the root system.It improves apple yield,quality,and water use efficiency,making it an ideal water efficient technology management model,Worth promoting.