Research On Effect Of Alternate Root-zone Drip Irrigation On Physiological,Growth And Yield Of Processing Tomato

Object:Processing tomato is one of the important economic crops in Xinjiang,but the shortage of water resources and the contradiction between supply and demand limit the productivity of processing tomato.Early studies reported that alternate partial root-zone irrigation（APRI）can use water stress signals to regulate optimal stomatal opening,reduce ineffective evaporation losses and total irrigation,and improve root-to-water and nutrient utilization without sacrificing photosynthetic products.Accumulate to achieve the purpose of saving water.The results of applying the alternate partial root-zone irrigation in processing tomato cultivation are still relatively small.Therefore,under the special geographical environment and climatic conditions in Xinjiang,the experimental processing tomato alternate partial root-zone irrigation pot experiment was carried out to accurately control the irrigation amount,and to study and analyze the root zone.The effects of alternate partial root-zone irrigation techniques on the growth characteristics,physiological characteristics,yield and quality indicators of processing tomato,in order to provide a reference for the optimal irrigation method and irrigation level of processing tomato.Methods:Using the pot planting experiment,the processing tomato variety“JinFan 3166”was taken as the research object.According to the local agronomic management,two factors of irrigation method and irrigation level were set,and the two factors were used to complete the treatment.Irrigation methods include alternate partial root-zone irrigation（APRI）,fixed irrigation（FPRI）and conventional irrigation（CDI）combined with drip irrigation film,with irrigation level of 5850 m³·hm^-2 and moderate deficit of 4500 m³.hm^-2 and severe deficit 3150 m³·hm^-2,APRI and FPRI irrigation is two-thirds of CDI,a total of 9 treatments,each treatment set 3 replicates.Results:（1）Compared with conventional irrigation treatment,the alternate root-zone irrigation under the mild stress（W₁）treatment effectively controlled the plant height,expanded the stem diameter and leaf area index,and effectively reduced plant growth redundancy.The plant height,stem diameter and leaf area index of processing tomato were significantly affected by the interaction of irrigation method and irrigation amount（P<0.01）.The plant height,stem diameter and leaf area index of the treated tomato were consistent with the“slow-fast-slow”rule of the logistic curve.The growth potential and maximum growth of plant height,stem diameter and leaf area index of processing tomato under different irrigation combinations were studied.The rates are as follows:AW₁>CW₁>CW₂>AW₂>FW₁>FW₂>CW₃>AW₃>FW₃.（2）The roots of processing tomato were concentrated in the surface layer（0²0 cm）.The effect of alternate partial root-zone irrigation on the root system of processing tomato was mainly on the small root system with surface layer（0²0 cm）and diameter≤2 mm.The root quality,root length,root surface area,root volume and average diameter of processed tomato were significantly affected by the interaction of irrigation and irrigation levels,and were significantly linearly positively correlated with yield.Increasing the irrigation amount was beneficial to root growth.Alternate partial root-zone irrigation significantly increased the characteristic parameters of the root system,reached the maximum value under the conventional irrigation level,and the highest yield,which increased yield by 18.84%compared with CDI.APRI also increased the the roots N,P and K nutrients,and APRI root activity was the highest in moderate deficits,which was significantly higher than conventional irrigation and fixed irrigation treatments of 6.12%and11.60%,respectively.By simulating the exponential functions of root density and soil depth under two-parameter and three-parameter models,it is found that the correlation coefficient between the three-parameter exponential fitting and the average root-zone density and the depth of the soil layer is significantly higher than that of the two parameters.However,when simulating conventional drip irrigation,the two-parameter model has a higher correlation coefficient than the three-parameter model.（3）The processing tomato leaves treated by alternate partial root-zoneirrigation with mild water stress（W₁）maintained high chlorophyll content,photosynthetic characteristics（P_n,T_r,and G_s）,fluorescence Characteristics（F_v/F_m,F_v/F₀ and q^p）,but to some extent reduce intercellular CO₂ concentration（C_i）and non-photochemical quenching coefficient（NPQ）,which indicated that under the premise of sufficient irrigation and water supply in the root zone,it can effectively reduce the intensity of photoinhibition,stimulate the compensation effect and self-light protection function,inhibit the decomposition of photosynthetic pigments,and benefit the secondary growth of plants.（4）Compared with conventional irrigation,the treatment of mild water stress（W₁）in alternate root-zone irrigation significantly increased the number of fruits per plant and reduced the weight of single fruit,but the total yield per plant increased by 0.02 kg/plant.The correlation between the yield of processing tomato and the number of fruits per plant（R²=0.9034）was greater than the correlation between yield and single fruit weight（R²=0.5425）.This indicates that the increase in production is mainly attributable to changes in the amount of fruit,and measures that are beneficial to increase the amount of fruit can increase the yield of processing tomatoes.Under the same water treatment conditions,APRI treatment showed higher irrigation water use efficiency,which was significantly higher than FPRI and CDI treatment irrigation water utilization efficiency by 53.51%and 50.86%,30.21%and 15.47%,8.43%and 15.38%,respectively.The biological water saving potential of the plant itself has been exerted.（6）Alternate root-zone irrigatione significantly increased the V_c content,lycopene,soluble sugar and sugar-acid ratio of processing tomato fruits under the same water conditions,and reduced the titratable acid content and soluble solids compared with fixed irrigation.By improving the fuzzy gray correlation degree method,the comprehensive quality evaluation of processing tomato was obtained,and the comprehensive index of processing tomato was ranked as AW₁>AW₂>CW₂>AW₃>CW₃>FW₂>CW₁>FW₃>FW₁,and the top of the alternate root-zone irrigation area was ranked 2nd.It is higher than conventional irrigation treatment,and the comprehensive quality of fixed irrigation treatment is the worst.Therefore,it is considered that the treatment of alternate irrigation in high water（W₁）and middle water（W₂）can be used as the optimal irrigation combination model for improving the comprehensive quality of processed tomato.Conclusion:Comprehensive processing tomato growth,physiology,yield,irrigation water use efficiency,quality and other indicators,the results of this test that the combination of APRI and mild water defict treatment(3900 m³·hm^-2)can be used for planting processing tomato water-saving and high-yield planting mode in the local area.