Comprehensive Effect Evaluation On Agronomic Quality Of Different Chinese Cabbage And Pepper Varieties In Southwest China Under Optimal Nitrogen Fertilizer

The large amount of nitrogen fertilizer in the vegetable system in Southwest China is the main factor limiting the low yield level and poor quality of vegetables in Southwest China.Optimizing nitrogen fertilizer management and screening suitable vegetable varieties is of great significance to improve the quality and yield of vegetables in Southwest China.However,the effects of optimized nitrogen management strategies on different vegetable types in this region are still unclear.Therefore,taking 6 typical Chinese cabbage varieties and 6 pepper varieties in Southwest China as the research object,two nitrogen levels of no nitrogen application and optimal nitrogen application,and three planting densities were set to determine the effects of optimal nitrogen management and different planting densities on the yield,nitrogen use efficiency and quality of different Chinese cabbage and pepper,and compare the differences among different varieties.In order to screen out high yield and high quality varieties of Chinese cabbage and pepper suitable for planting in southwest China and the best planting density,to provide reference for Chinese cabbage planting in Southwest China and even the whole country.The main results are as follows:1.Compared with no nitrogen fertilizer treatment,the total yield of Chinese cabbage was increased by 130% to 289%,the plant nutrient absorption was significantly increased,the vitamin C content was increased by 5.0% to 38.3%,the flavonoid content was decreased by 4.5% to 275%,and the nutritional quality index of Chinese cabbage was significantly increased under the optimal nitrogen application condition.Under optimal nitrogen fertilizer management conditions,different Chinese cabbage varieties had different response degrees to nitrogen fertilizer.Shandong No.4and Fengkang70 Chinese cabbage varieties were nitrogen efficient varieties.Its yield,nitrogen use efficiency,nitrogen accumulation,phosphorus accumulation and vitamin C content were significantly higher than those of other varieties 4.0%-42.0%,44%-225%,10.6%-61.4%,12.9%-52.6% and 1.2%-8.3%,respectively,and it also had better absorption of micronutrients.Among them,the accumulation of calcium,magnesium and zinc of Fengkang 70 variety was the highest,and the content of iron and manganese of Shandong No.4 variety was the highest.When the planting density was the highest(30cm×40cm),the cabbage yield was the highest.Compared with the minimum planting density(50cm×40cm),the total cabbage yield and commodity yield increased by 18.9% and 18.8%,respectively.In general,the yield,nutrient absorption,nitrogen use efficiency and quality of Shandong No.4 and Fengkang 70 were significantly better than other varieties,which was suitable for spreading planting in southwest China,and 30cm×40cm was the best planting density.2.Optimized nitrogen fertilizer management significantly improved the yield,nutrient uptake and quality of pepper.Under optimal nitrogen management and high planting density comprehensive management measures,King,Luojiaotiaojiao 28 and Erjingtiaojiao had higher response to nitrogen fertilizer and were nitrogen efficient varieties.Their yields were 4.0%～42.0% higher than other varieties.Lujiaotiaojiao 28 and Erjingtiaojiao had the highest fruit dry matter accumulation.The accumulation of nitrogen,phosphorus and potassium of King,Luojiaotiaojiao 28 and Erjingtiao varieties was the highest,which was significantly higher than other varieties22.7%-227%,33.3%-203% and 26.0%-281%,respectively.The content of vitamin C of King variety was the highest,which was significantly higher than other varieties12.8%-70.9%.Under optimal nitrogen fertilizer treatment,the highest pepper yield was obtained when the planting density was the highest(40cm×60cm).Compared with the minimum planting density(60cm×60cm),the pepper yield was significantly increased by 39.2%.In conclusion,the results showed that the varieties of King,Luojiaotiaojiao 28 and Erjingtiao pepper were more suitable for planting in southwest China,and the optimal planting density was 40cm×60cm.