Study On The Effect Mechanism Of Substrate Cultivation On Tomato Growth Characteristics

In order to effectively improve the utilization rate of agricultural waste,a drought-resistant and root-promoting substrate was prepared by mixing agricultural waste such as compost,straw and clay.The effects of water and fertilizer coupling effect and different substrate ratios on plant height,stem diameter,yield,quality,Water Use Efficiency（WUE）and Partial Factor Productivity of Fertilizer（PFP）of tomato cultivated in’Aiji 3041’substrate were studied.Taking the local actual production of water and fertilizer application as the control group CK,9 groups of substrate water and fertilizer coupling treatments were set up,3 groups of drip irrigation water W1（100%ET₀,ET₀ is the reference crop evapotranspiration）,W2（80%ET₀）,W3（60%ET₀）and 3 groups of fertilization（N-P₂O₅-K₂O）levels F1（240-115-137 kg/hm²）,F2（180-88-121.2 kg/hm²）,F3（112-50-82 kg/hm²）,a total of 10 groups of coupling treatments.According to different volume ratios,five groups of substrate ratios were set as T1（organic fertilizer:loessial soil:straw=4:5:1）,T2（organic fertilizer:loessial soil:straw:distiller’s grains=3:5:1:1）,T3（organic fertilizer:loessial soil:straw:distiller’s grains=2:5:1:2）,T4（organic fertilizer:loessial soil:straw:distiller’s grains=1:5:1:3）,T5（loessial soil:straw:distiller’s grains=5:1:4）.The multi-objective optimization model of tomato yield,WUE,PFP and fruit comprehensive quality was established.The genetic algorithm multi-objective optimization method was used to find the Pareto optimal solution of the model and the AquaCrop model was used to simulate its biomass,canopy coverage,soil water content and yield.The main research contents are as follows:（1）The effects of different water and fertilizer treatments on the growth,quality and yield of substrate cultivated tomato were clarified.Nine groups of substrate water and fertilizer coupling treatments were set up.The variation of plant height,stem diameter and root characteristics of substrate cultivated tomato under different water and fertilizer treatments was analyzed by water and fertilizer coupling test.Taking the application amount of water and fertilizer as the independent variable,the sugar-acid ratio,yield,water use efficiency and fertilizer partial productivity as the dependent variables,the regression equation was established,and the multi-objective optimization method was used to solve the problem,and the water and fertilizer treatment suitable for substrate cultivation of tomato was determined.The results showed that the plant height,stem diameter,root weight,total root length,total root surface area and total root volume of tomato cultivated in substrate at different growth stages were significantly affected by different water and fertilizer treatments.Under the same water and fertilizer treatment,the plant height and stem diameter of W2F1increased by 16.3%and 24.2%,respectively,and the root weight,total root length and total root surface area increased by 36.0%,6.27%and 3.94%,respectively.By using VIKOR method,it was found that the flavor quality and yield of tomato cultivated in substrate under low water and high fertilizer treatment were the best,and the benefit ratio Q_i value was the smallest,followed by low water and fertilizer.The multi-objective optimization method based on genetic algorithm showed that the best irrigation and fertilization treatment for substrate cultivated tomato was low water fertilizer treatment W3F2.The results can provide reasonable scientific management of water and fertilizer for high quality cultivation of tomato.（2）Distiller’s grains,straw and livestock manure were used to make substrates according to different volume ratios of T1,T2,T3,T4 and T5.The physical and chemical properties of substrates with different ratios were determined.The Van-Genuchten model was used to fit the soil water characteristic curves of different substrates.The effects of different ratios on soil specific water capacity,soil equivalent pore distribution and water constant of substrates were investigated.The effects of different substrate ratios on the growth and development,root characteristics,yield,quality,water use efficiency and fertilizer partial productivity of tomato were studied.The results showed that compared with CK treatment,T2-T4 treatment could reduce soil acidity and electrical conductivity,and significantly increase total phosphorus and total potassium content.The fitting accuracy of soil water characteristic curve of all ratios is high.The addition of distiller’s grains and organic fertilizer can increase the soil specific water capacity of the substrate,the number of soil extremely micropores,micropores and small pores;in different ratios,the change of substrate ratio affected the total root length,total root surface area,total root volume,root tip and root diameter of tomato.The maximum FPF and WUE of T1 treatment were 28.34 kg/kg and 2.95kg/m³,respectively,which increased by 9.67%compared with CK treatment.The results provide a theoretical basis for the efficient utilization of agricultural wastes such as distiller’s grains and straw.（3）Based on the AquaCrop model,the growth process of tomato under different substrate ratios was explored.A multiple regression equation was established with tomato simulated yield,simulated biomass,water use efficiency and fertilizer partial productivity as the objectives,and the substrate ratio was determined by multi-objective genetic algorithm.The results showed that the correlation coefficient R²between the measured values and the simulated values of canopy coverage and soil moisture content of each substrate treatment was above 0.8.The R² between the measured values and the simulated values of tomato yield and biomass were 0.9175and 0.8018,respectively.The relative error Pe of the substrate treatment group was less than 10%,and the simulation accuracy was high.The model can be applied to the simulation of substrate cultivation tomato under different ratios.The multi-objective optimization method based on genetic algorithm showed that the suitable substrate ratio for tomato growth was T5 treatment,to provide a theoretical basis for the cultivation of high-quality tomatoes.