Variety Selection And Optimization Of Water And Fertilizer Management Scheme Of Pepper Suitable For Substrate Bag Culture In Northern Shaanxi Province

Pepper(Capsicum annuum L.)is the vegetable crop with the largest plant area and the highest output value in China,and it is also one of the main crops cultivated through substrate in the protected agriculture of Yan’an area in northern Shaanxi province.Screw pepper is favored by consumers because of its unique flavor.However,few attentions have been paid to the dominant varieties suitable for substrate cultivation and irrigation and fertilization management of pepper grown in substrate cultivation in northern Shaanxi province.In this study,20 kinds of screw pepper varieties were chosen as experimental materials and 10 indicators were measured.Principal component analysis(PCA),technique for order preference by similarity to ideal solution(TOPSIS),membership function analysis(MFA)and grey relational degree analysis(GRDA)were used to evaluate the yield and quality indicators of each screw pepper variety.After the prior consistency test(Kendall-W),fuzzy Borda evaluation method was used for combination evaluation to select the variety of screw pepper suitable for substrate bag culture in northern Shaanxi province.In addition,the more suitable irrigation frequency and nutrient solution supply mode of substrate bag culture in northern Shaanxi were explored.The main research results are as follows:1.The suitable varieties for substrate bag culture in northern Shaanxi province were screened.The evaluation results of the fuzzy Borda combination evaluation method showed that the top 5 varieties were’Silk Road New Star’,’HP29047’,’Silk Road Star’,’Longxuan 339’,and’Biosow 019’.2.The optimal coupling scheme of irrigation frequency and nutrient solution supply of pepper cultivation in spring and summer based on daily total irrigation was determined.Irrigation frequency,nutrient solution supply and its coupling had different effects on plant height,stem diameter,dry matter mass accumulation in different tissues and root-shoot ratio of pepper plants at different growth stages,and had highly significant effects on substrate enzyme activity,yield,water use efficiency and fertilizer partial productivity of pepper plants(P<0.01).The irrigation frequency had highly significant effects on all quality indexes(P<0.01)except fruit shoulder length;the nutrient solution supply had highly significant effects on vitamin C,soluble protein,capsaicin and hihydrocapsaicin(P<0.01),but had no significant effect on other quality indicators;irrigation frequency and nutrient solution supply coupling had highly significant effects on the quality indicators(P<0.01)except for the fruit wall thickness.The PCA-TOPSIS method,membership function analysis and grey relational degree analysis had the same evaluation results on the determination index,and the best treatment was as follows:the irrigation amount required to maintain the water content of the substrate 55%～60%was the total irrigation amount per plant per day,and the irrigation frequency was once a day.Nutrient solution supply was 250 m L/plant/d from flowering until just before 3rd layer fruit harvesting;500 m L/plant/d after 3rd layer fruit harvesting.The treatment had the best fruit quality,the highest yield,water use efficiency and nitrogen,phosphorus and potassium fertilizer partial productivity,which were 74482.24 kg/hm~2,34.21 kg/m~3,625.95kg/kg,679.54 kg/kg and 367.23 kg/kg,respectively.3.The optimal coupling scheme of irrigation frequency and nutrient solution supply of spring-summer stubble and autumn-winter stubble pepper cultivation based on substrate water content was determined.The comprehensive evaluation results of PCA of autumn-winter stubble and spring-summer stubble were consistent,and the comprehensive score of IF3NS2 treatment was the highest,and the yield and fertilizer partial productivity of pepper under this treatment were the highest,and the fruit qualities were better.Therefore,the optimal irrigation frequency and nutrient solution supply scheme of substrate bag culture pepper based on substrate water content was as follows:on the premise that the water content of the substrate was controlled at55%～60%,irrigation water was supplied 4 times/d after the flowering of door pepper,and the irrigation was stopped every time until the water content of the substrate was60%.A pepper plant was irrigated with 250 m L a dose of Yamazaki pepper nutrient solution every day.After each layer of fruit was harvested,the nutrient solution supply increased by 50 m L/plant/d,and did not increase until it increased to 500m L/plant/d.