Optimization of Integrated Water and Nitrogen Regulation System in Apple Based on Multi-Objective Comprehensive Evaluation
[Objective]The aim of this study was to explore the comprehensive impact of integrated drip irrigation and nitrogen regulation on the growth,physiology,water-nitrogen utilization efficiency,yield,and fruit quality of apple trees in northern semi-arid regions,and to determine the optimal water-nitrogen regulatory system.[Method]The experimental design involved two regulatory factors:irrigation and fertilizer application.Three irrigation levels were set up,representing 75%-90%(W1),60%-75%(W2),and 45%-60%(W3)of field water capacity,respectively.Four fertilizer application levels were set,with N-P2O5-K2O of 18-12-6 g/plant(F1),15-12-6 g/plant(F2),12-12-6 g/plant(F3),and 9-12-6 g/plant(F4).The study analyzed the effects of different water-nitrogen treatments on the growth and physiological indicators,water-fertilizer utilization efficiency,dry matter,yield,and fruit quality of apple trees.With the objectives of water and fertilizer saving,as well as high yield and high quality,a comprehensive evaluation model was established by combining the AHP-CRITIC combination weight method and the TOPSIS model.[Result]Water-fertilizer coupling produced highly significant effects on plant growth,chlorophyll content(SPAD),irrigation water use efficiency(IWUE),fertilizer partial productivity(PFP),fruit weight and yield of apple trees,and significant effects on basal stem growth.Under different water-fertilizer coupling treatments,the moderate deficit of irrigation and nitrogen application treatments were more favorable to increase plant growth,basal stem growth,leaf area,dry matter,yield,water use efficiency(WUE),water productivity(WP),IWUE,FPP,and fruit weight of apple trees,and their maximums occurred in the F2W2 treatment.The SPAD,photosynthesis rate,and transpiration rate of apple trees increased with increasing amounts of irrigation and nitrogen,but the moderate deficit of irrigation and nitrogen application treatments had no significant effect on physiological indices,with the F1W2 and F2W1 treatments decreasing by only 3.5%,3.1%,7.7%,and 3.5%,3.1%,and 3.8%,respectively,compared with F1W1.The AHP-CRITIC combination was used to determine the combination weights of the indicators,in which the weight of yield was the largest,amounting to 0.406,followed by vitamin C.The TOPSIS algorithm was used to construct a comprehensive multi-objective evaluation system for apples,and the result was that the comprehensive score under the F2W2 treatment was the highest,amounting to 0.8974,with the F1W2 and F2W1 treatments coming next,and the F4W3 treatment had the lowest score of 0.0177.The established interaction response model of coupled water and fertilizer in apples shows that the effects of both irrigation and fertilizer application on the composite score of apple growth were parabolic lines with downward opening.The apple growth composite scores showed a trend of increasing and then decreasing with increasing irrigation or fertilizer application,which was consistent with the diminishing reward effect,i.e.,irrigation and nitrogen application exceeding a certain range and then continuing to increase would lead to a decrease in composite scores,which was not obvious for the improvement of apple growth.When the fertilizer application coded value X1 was 0.681 and the irrigation coded value X2 was 0.488,the highest apple composite score was 0.923,i.e.,the fertilizer application rate was 34.56 g·plant-1(N-P2O5-K2O:16.56-12-6 g/plant),and the irrigation rate was controlled at 82.3%of field water capacity,so this irrigation and fertilizer application treatment was the most desirable for the growth of apples.[Conclusion]The comprehensive evaluation system constructed using the AHP-CRITIC-TOPSIS method could effectively determine the optimal water and nitrogen regulation system for apples,which provided a theoretical and practical basis for the actual production of apple orchards in northern semi-arid regions.
applegrowth physiologydrip irrigationwater and fertilizer utilizationintegrated evaluation modelwater and nitrogen regulation
国家科技期刊平台
NSTL
万方数据
