Effect of nitrogen, phosphorus and silicon calcium fertilizer on yield and quality of pepper

【Objectives】 Long-term unreasonable use of concentrated chemical fertilizers brings unbalance supply of other nutrients, calcium, magnesium, sulfur, silicon and other trace elements fertilizers emerge as crop yield limiting and quality factors. This article is aimed to determine the optimum fertilization of silicon-calcium fertilizer (SiCa), nitrogen fertilizer (N) and phosphate fertilizer (P) in pepper. 【Methods】 A secondary saturation D-optimal design with three factors was applied to analyze the effect of nitrogen, phosphorus and silicon calcium fertilizer on yield and quality of pepper using the DPS software. According to data of pepper yield and quality got in 2013, regression equation between the pepper yield and quality and nitrogen, phosphorus and silicon calcium fertilizers was set up through optimizing the polynomial regression analysis first. Then, the feasibility of model, including main and single factors and factor interaction, was tested using F test of the equations and t test of the regression coefficients. The model decision was finally simulated by computer, and the fertilization scheme was put forward for the high yield and good quality of the pepper. 【Results】 The results of model analyses show that the impacts of Si-Ca, N and P fertilizers on the yield and quality of pepper are significant, and the interaction between the any two factors are also significant. In the coding range, taking the interaction effect of Si-Ca and N for a case, the interaction space with higher pepper yield is medium Si-Ca level with high N level, while the interaction space with better pepper quality is high Si-Ca level with medium N level. The affected orders of three factors on pepper yield are: N P Si-Ca, while the influences on the quality are opposite. Pepper yield and quality are improved with the applied amounts of Si-Ca, N and P increasing under the soil fertility level, and decreased under the high fertilization level. Through the computer simulation, when the yield reaches 4500-6000 kg/ha and the comprehensive score of quality is above 95, the optimal fertilization amounts of Si-Ca, N and P are 304.76-398.24 kg/ha, 220.05-263.26 kg/ha and 44.80-64.50 kg/ha respectively. Considering marginal utility, when the yield reaches 5916.23 kg/ha and the maximum economic benefit is 80548.64 yuan/ha, the optimal fertilization amounts of SiCa, N and P are 332.66 kg/ha, 250.58 kg/ha, 57.75 kg/ha respectively, and the ratio is 1: 0.75: 0.17. 【Conclusions】 The proper application of Si-Ca, N and P can increase the yield and quality, and regulate pepper nutrient absorption and other functions, but excessive application can cause a reduced yield, quality and so on. The model constructed can explain in detail the influence of three kinds of fertilizers on the yield and quality of pepper, and the interaction of the three fertilizers can be obtained through the simulation model.