Effect Of Nitrogen And Potassium Levels On The Growth Development And Characteristics Of Nutrient Absorption And Utilization In Grafted Peppers

The effects of nitrogen and potassium on the yield of grafted and own-root peppers were investigated with the design of two factors and double saturated D-optimal regression. A mathematical model for the optimization was established using nitrogen(N) and potassium(K2O) amounts as the independent variables, and the yield of grafted and own-root plants as objective function. Based on the above result, we studied the absorption and distribution lows of nitrogen and potassium in grafted and own-root peppers, as well as the effect of nitrogen application combined with potassium on the physiological characteristics and yield of grafted peppers. The results are as follows:1. The results showed that nitrogen and potassium significantly influenced the yield of grafted and own-root peppers, and there were interactive effect between nitrogen and potassium. However, potassium had higher effect on the yield of pepper. Through simulated computation, the schemes of optimized fertilization of grafted and own-root peppers were finally obtained. The yield of grafted pepper could reach to 3300 kg·667m-2 or more when the fertilizer rates are N 21.74~50.14 kg·667m-2 and K2 O 42.05~74.40 kg·667m-2; the similar yield of own-root pepper could obtains when the fertilizer rates are N 27.43~40.46kg·667m-2 and K2 O 57.89~77.89 kg·667m-2. The suitable ratio of N∶K2O of grafted pepper is 1:1.96, and that of own-root pepper is 1:1.85.2. Peppers grow slowly in the vegetativeperiod, and the dry matter accumulation is the largest in leaves, while the least in roots and fruits. Duringthefruit stage, the peppers showed a rapid growth and development, and the dry matter accumulation decreased gradually in leaves, but increased in fruits.3. The absorptive volume of N, P2O5 and K2O increased in peppers as growth stage progress. During the totalgrowth period, the absorptive amount of N, P2O5 and K2O in grafted peppers was 4.4 g·plant-1, 2.53 g·plant-1 and 8.0g·plant-1 respectively, and the ratio of N, P2O5 and K2O is 1:0.58:1.82, while in own-root peppers was 3.4g·plant-1, 1.91 g·plant-1 and 6.0 g·plant-1 respectively, and the ratio of N, P2O5 and K2O is 1:0.56:1.76.4. Asthe growth stage progress, the proportions of N and P2O5 showed a decrease in distribution to leaves, whereas an increase in fruits. Less change was found in the proportions of N and P2O5 distributed to roots and stems. The proportion of K2 O distributed to stems was the most and to fruits and roots were the least in the vegetative period. As the growth stage progress, the proportion of K2 O distributed to fruits increased, whereas to roots, stems and leaves decreased. During the totalgrowth period, the nitrogen utilization efficiency of grafted and own-root peppers were 33.30 % and 26.99 % respectively, and the potassium fertilizer utilization efficiency of them were 30.99 % and 23.57 % respectively.5. Nitrogen application combined with potassium can significantly increase growth, shorten blooming time, improve photosynthetic rate root activity, root absorptive area and active absorptive area, enhance activities of rhizosphere soil enzymes. The yield of nitrogen application combined with potassium treatment was increased by 31.2% compared with the control.