| The bagged substrate has been widely used in agriculture due to its good content for high yield and quality of tomato.Meanwhile,the problem of unbalanced nutrients content for plant growth and increasing amount of substrate waste has been noticed.Few researches have been down on this part and most farmers are using bagged substrate by their experience in practical,like the substrate filling height and the placement of substrate bag in the greenhouse.In addition,the formula of nutrient solution used in tomato cultivation substrate was designed for hydroponic systems.It is not suitable in current growth field.This study is aiming to improve this situation by designing a resource-conserving and nutrient balanced management scheme of bag culture which can promote high quality and high yield of tomato,and can be applied to industrial agriculture tomato production.We took‘burberry'cultivar as our model plant and focused on two research sections in this study.The first one is the placement depth of substrate in the bags and bags in the greenhouse.The substrate was filled with different depths?7.5,10.5,13.5 cm?and the substrate bag was placed in different ways?ground placement and ground subsidence 20 cm?.The effect of the interaction between different depth of substrate filling and the way of substrate bag placement on several tomato biological parameters were measured.It includes plant growth,tomato yield,tomato quality and nutrient content.In the second section,we studied the nutrient solution formulations in modification of four elements,nitrogen?N?,phosphate?P?,potassium?K?,and calcium?Ca?.23 different nutrient solution formulations were set up by using the four factor five level secondary regression response surface.We measured tomato yield and quality from different formulation treatments and a quadratic regression mathematical model was established.The cultivation effect of Yamazaki tomato nutrient solution formula was used as control treatment.Take this as a standard,we verified the best and the worst formula simulated in the model,and the highest and the lowest comprehensive score in 23 different nutrient solution formulations.Those formulations were applied in field experiments and the data were recorded on the tomato growth,photosynthesis,substrate enzyme activity,yield,quality and nutrient absorption.Those data were then applied to the model to optimized nutrient solution formula.The main findings are as follows:1. The tomato growth in 13.5 cm substrate depth?substrate supply is 9 L/plant?with ground placement in spring had the best results by measureing the indexes of yield,quality,nutrient uptake and substrate nutrient utilization.?1?Substrate depth had significant effects on tomato yield and fruit quality.The effect of substrate bag arrangement on tomato yield was not significant,but the contents of soluble protein,lycopene,nitrate and organic acid in fruit were significantly affected.There was significant interaction between substrate depth and substrate bag arrangement on tomato nitrate content.With the increase of substrate depth,tomato yield and quality were significantly improved.When the substrate depth is 13.5 cm,the yields of the tomato were the highest?3.83 kg/plant?.?2?The substrate bags arrangement and substrate depth had significant effects on the accumulation of P and K in flowering stage,initial fruit stage and full fruit stage of tomato.The depth of the substrate had a significant effect on the absorption of N in flowering stage,initial fruit stage and full fruit stage of tomato.There was significant interaction between substrate bags arrangement and substrate depth on the cumulative uptake of N,P and K in tomato plants at flowering stage and initial fruit stage.The N,P and K nutrient utilization efficiency of the substrate was the highest in the 13.5 cm substrate depth,and there was no significant difference in the nutrient utilization efficiency of the substrate between different substrate bags arrangement.2. The tomato substrate bag culture with the combination of 24.83 mmol·L-1N,4.50mmol·L-1P,9.49 mmol·L-1K and 5.73 mmol·L-1Ca is recommended.This is based on the optimization of nutrient solution formulation and validation test of tomato substrate bag culture.?1?The quadratic regression mathematical model established with N?X1?,P?X2?,K?X3?,Ca?X4?as independent variables.The yield and quality comprehensive evaluation score?Y?of different nutrient solution formulations was used as dependent variables.We can obtain the following mathematical model Y=0.0482-0.0003X1+0.0017X2+0.0014X3+0.0005X4-0.0039X12+0.0007X22-0.0024X32-0.0025X42+0.0022X1X2+0.0025X1X3-0.0009X1X4.The analysis showed that N,P,K and Ca influences order of tomato comprehensive evaluation score is P,K,Ca,N from large to small.P,K and Ca have a positive effect on the comprehensive evaluation value of tomato,and N has a negative effect on the comprehensive evaluation value of tomato.There was interaction between N and P,N and K,N and Ca,and the interaction was most significant when the concentration of elements in N and K,N and Ca were near zero level,the comprehensive evaluation score of tomato was higher.?2?The results showed that T1?the best formula simulated by equation?,T3?the highest scoring formula of 23 groups?and CK?Yamazaki tomato nutrient solution formula?were beneficial to tomato growth.T2?the worst formula simulated by equation?and T4?the lowest scoring formula of 23 groups?had little effect on tomato growth.At different periods,the photosynthesis,the activity of sucrase and urease in substrate of tomato were all the highest in T1 treatment,followed by T3 and CK treatments.T2 and T4 treatments were worst.The activity of catalase and neutral phosphatase in substrate showed that higher in T1?T3 and CK treatments than in T2 and T4 treatments.The N,P,K and Ca element accumulation of T1 and T3 treatments were significantly higher than those of CK treatment at full fruit stage and the end of fruit stage.The N element utilization difference of T1,T3and CK treatments were not significant within three treatments but they were significantly higher than that of T2 and T4 treatments.The tomato from CK treatment had the highest P element utilization.The utilization of K element in T1 and T3 treatments increased by16.69%and 7.74%respectively compared with the CK treatment,while the Ca element utilization of T1 and T3 treatments increased by 24.14%and 10.96%respectively compared with CK treatments.The K and Ca elements utilization of T2 and T4 treatments were significantly lower than CK treatment.We also conducted experiments to verify the effect of comprehensive evaluation and analysis of yield and quality of the five treatments in the cultivation.The order of the comprehensive evaluation scores of each treatment from high to low was T1,T3,CK,T4,T2.This proved the accurate reliability of the equation model in practical application.Meanwhile,the optimal formula simulated by the equation was most conducive to the improvement of tomato yield and quality. |
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