| The gully area of the Northwest Loess Plateau is an important production base for high quality apples in China.Due to unreasonable management measures and blind irrigation and fertilization in most orchards,the development of fruit production in the area is hindered,so the productivity of irrigation water and the output value of the fruit industry are improved,and the cause of unreasonable fertilization The resulting environmental pollution and other issues are the fundamental prerequisite and important guarantee for the sustainable development of the fruit industry in the region.Drip irrigation fertilization is a major technical means to improve water and fertilizer use efficiency and develop water saving agriculture.Different drip irrigation fertilization technical parameters affect the growth of fruit trees by affecting the supply and distribution of water and fertilizer,and indirectly lead to differences in yield and fruit products.Therefore,studying the effects of different fertilization technical parameters and their combinations on the growth,yield and quality of apple trees under drip irrigation conditions can provide a theoretical basis for choosing scientific and reasonable fertilization methods and promoting high quality and high yield apples.It is useful for orchard management and fruit industry development in Northwest China.It is of great significance.This study took apple trees as the research object.From 2017.10 to 2020.10,a three factor two level field experiment was arranged in Luo Chuan,Shaanxi Province.One row,one tube and two tubes(P1,P2)were set up,and the distance between drippers was 30 cm,50 cm(D1,D2),the fertilization cycle is 15 days and 30 days(T1,T2).In addition,in October 2018,a comparative test of two nitrogen fertilizer forms,urea and urea ammonium nitrate solution(U,UAN),was added to analyze the effects of different fertilization technical parameters and their combinations on the growth of apple trees under drip irrigation conditions,and explored the effects of experimental factors on the growth of apple trees.The effects of apple yield,water use efficiency,and apple quality are comprehensively evaluated by the TOPSIS model based on combination weighting.At the same time,by revealing the residual and distribution of nitrate nitrogen in the 0～200 cm soil of the apple orchard,the selection can promote the growth and development of fruit trees.The combination of drip irrigation and fertilization technology parameters to improve fruit quality has achieved the following main research results:(1)The influence law of drip irrigation fertilization technical parameters on apple tree growth was explored.Dynamic monitoring of changes in the growth indicators of apple trees,including main side branch stem thickness,new shoot length,plant height,stem circumference,crown width,and the study found that the capillary arrangement interacts with the distance between the drippers and the secondary interaction of three factors.The growth of the stem thickness is significant.The influence of the test factors on the other indicators alone and interactively is not significant.As far as the treatment combination is concerned,the maximum dry week and crown width both appear in a row with one tube,the emitter spacing is 50 cm,and the fertilization cycle is 30 days;the maximum new shoot length appears in a row with two tubes,the dripper spacing is 30 cm,and the fertilization cycle is 15 days.The maximum stem thickness of the main branch appears in a row with one tube,the dripper spacing is 50 cm,and the fertilization cycle is 15 days;the maximum lateral branch stem thickness occurs in a row with two tubes,the dripper spacing is 50 cm,and the fertilization cycle is 15 days.Urea ammonium nitrate solution treatment is beneficial to promote the increase of various growth indicators of apple trees.(2)Reveals the influence law of drip irrigation fertilization technical parameters on apple yield.The impact of drip irrigation and fertilization technical parameters on apple yield is as follows: the capillary arrangement,the distance between drippers and their interaction in2018 are significant;the single factor effect is not significant in 2019,the interaction of three factors is significant,and the three factors and their interaction in 2020 The interaction effect is significant.Considering that fruit trees suffered from freezing damage in 2018 and 2020,the data is not representative.According to the results of 2019,two pipes in a row are higher than one pipe in a row,reaching a significant level when the distance between emitters is 50 cm and the fertilization cycle is 30 days.Therefore,it is recommended under drip irrigation conditions.The combination of technical parameters is two tubes in one row,50 cm distance between emitters,and 30 days fertilization cycle.The form of nitrogen fertilizer has no significant effect on yield.(3)The effects of drip irrigation and fertilization technical parameters on apple quality indexes and comprehensive quality indexes were explored.The influence of test factors on apple quality in 2018 is that the capillary arrangement method and the distance between the drippers have significant effects on the weight,vertical and horizontal diameter,Vc,and soluble sugar of a single fruit,and there is a significant interaction between the capillary arrangement method and the distance between the drippers.Fertilization cycle has significant effects on titratable acid,sugar acid ratio,solid acid ratio and hardness.In 2019,the capillary layout method only has a significant effect on the transverse diameter and the solid acid ratio,and the distance between the emitters has a significant effect on the soluble sugar,sugar acid ratio,and solid acid ratio.The impact of test factors on apple quality in 2020 is roughly the same as in 2018.The TOPSIS model based on subjective and objective weighting was used to comprehensively rank apple quality,and it was determined that under the experimental conditions,the comprehensive quality of the treatment with two pipes in one row,50 cm distance between drippers and 15 days fertilization cycle was the best;in terms of nitrogen fertilizer form,urea nitrate The comprehensive quality of ammonium solution treatment is better than that of urea treatment.(4)The effect of drip irrigation fertilization technical parameters on the distribution and accumulation of soil nitrate nitrogen during the harvest period was revealed.In 2018 and 2019,as the soil depth increases,the nitrate nitrogen content first increases and then decreases.In 2020,due to the large amount of precipitation,nitrate nitrogen will undergo obvious deep leaching,and the overall distribution will move downward..It has been determined that most of the fine roots of the fruit trees in this test are distributed above the 80 cm soil layer.Three years data show that the treatment with two pipes in a row,50 cm distance between emitters,and 30 days fertilization cycle has a larger accumulation in the0～80 cm soil layer,while one row has one The treatment with the distance between the tube and the dripper of 30 cm and the fertilization cycle of 30 days is more prone to deep leaching.The technical parameters of drip irrigation and fertilization have an impact on the accumulation of soil nitrate nitrogen in the 2 m soil layer,and the differences between the treatments are significant.According to the results of 2018,the maximum accumulation of nitrate nitrogen in the 2 m soil layer appears in a row with one tube,and the emitter spacing is 30 cm.The fertilization cycle is 30 days,and the minimum value is one tube per row,the distance between drippers is 50 cm,and the fertilization cycle is 30 days.In 2019 and 2020,the maximum accumulation of nitrate nitrogen in the 2 m soil layer for two consecutive years all appeared in the same treatment,that is,two pipes in one row,50 cm distance between emitters,and 30 days fertilization cycle.The minimum value also appeared in the same treatment,that is,two tubes in one row,30 cm distance between drippers,and 30 days fertilization cycle. |
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