Study On Water-iron Coupling Scheme Of Pepper With Substrate Bag Cultivated In Solar Greenhouse

Pepper plays an important role in Chinese vegetable production,and substrate cultivation of pepper has become one of the modes of efficient production in modern agriculture.Water and fertilizer management is an important technology for high quality and high yield of pepper,and Fe is one of the essential trace elements for crop growth,and the reasonable application of Fe fertilizer is beneficial to enhance the photosynthetic capacity of pepper and thus achieve yield increase.However,there is a relative lack of research on the coupling effect of irrigation volume and Fe²⁺concentration on pepper production.Therefore,this paper studied the effect of different irrigation volumes{30%-40%（2021 autumn crop removal）,40%-50%,50%-60%and 60%-70%of the relative volume water content of substrate}and nutrient solution Fe²⁺concentration{standard Yamazaki Pepper nutrient solution formulation Fe²⁺concentration of 200%（6.50 mg/L）,150%（4.88 mg/L）,100%（3.25 mg/L）and 50%（1.63 mg/L）}on the growth,yield,fruit quality,nutrient uptake and fertilizer bias productivity of pepper of different cultivation stubble,through comprehensive evaluation to obtain the best water-iron coupling for each index fit The optimal treatment was validated in spring 2022.The main research results are as follows:1.The results of the spring crop experiment in 2021 showed that the irrigation amount had a highly significant effect（P<0.01）on yield,fruit quality and fertilizer bias productivity;Fe²⁺concentration had a highly significant effect（P<0.01）on root dry matter mass;both irrigation amount and Fe²⁺concentration had a highly significant effect（P<0.01）on root-to-crown ratio and single fruit weight of pepper;the coupling effect of both had a highly significant effect（P<0.01）on fruit quality,element The coupling effects on fruit quality,element accumulation and utilization were all highly significant（P<0.01）.The overall evaluation showed that the Ci value of W4Fe4 treatment was the highest（0.71）,and the yield of pepper under this treatment was 74771.45 kg/hm²with a fruit weight of 60.29 g.The fruit vitamin C content was 94.45 g/100g,soluble protein content was 0.55 mg/g,free amino acid content was 628.32μg/g,reducing sugar content was 1.83%,and capsaicin content was 73.23%.Therefore,the optimal water-iron coupling treatment for spring crop substrate bagged peppers was:irrigation based on substrate water content of 60%-70%and Fe²⁺supply concentration of 1.63 mg/L.2.The results of the autumn crop trial in 2021 showed that irrigation rate had a highly significant effect（P<0.01）on yield,Fe accumulation and utilization at different fruiting periods;irrigation rate,Fe²⁺concentration and their coupling effects on fruit quality,Fe accumulation and distribution rate at the beginning of fruiting,Fe accumulation and utilization at the beginning of fruiting,root Fe³⁺reductase（FRO）content,stem wounding fluids Citric acid（Cit）content,substrate effective Fe content,and Fe utilization rate were all highly significant（P<0.01）.The comprehensive evaluation yielded the highest Ci value（0.72）for the W2Fe4 treatment,which yielded 72291.50 kg/hm²,85.71 g/100g of vitamin C,0.55 mg/g of soluble protein,328.53μg/g of free amino acids,2.16%of reducing sugars,and 98.41 ng/L of capsaicin under this treatment.98.41 ng/L,Fe accumulation was 2.52 g/g DW,and Fe utilization reached 88.32%.Therefore,the optimal water-iron coupling treatment for autumn crop substrate bagged peppers was:irrigation based on substrate water content of 50%-60%and Fe²⁺supply concentration of 1.63 mg/L.3.The top 5 water-iron coupling treatments in the overall evaluation of the spring and autumn 2021 trials were validated in spring 2022.The comprehensive evaluation using entropy-weighted-TOPSIS resulted in the T1 treatment(substrate water content of50%-60%and Fe²⁺concentration of 1.63 mg/L)ranking 1st in the comprehensive evaluation,with pepper yield of 81522.14 kg/hm²,fruit vitamin C content of 98.57 g/100g,soluble protein content of 0.54 mg/g,free The optimal solution for water-iron coupling in substrate bagged peppers was based on 50%-60%water content of the substrate for irrigation,and the Fe²⁺supply concentration was 1.63 mg/L（Na₂Fe-EDTA concentration was 12.5 mg/L）.