| Cabbage and pepper are important cultivated vegetables in China.Plug seedling is the main method of seedling raising.In order to ensure the comprehensive,balanced and appropriate supply of nutrients in the plug seedling of cabbage and pepper,while taking into account the different nutrient absorption capacity of seedlings and sensitivity to nutrient deficiencies during vegetable seedlings,it is necessary to apply a quantitative and precise amount of nitrogen,phosphorus and potassium fertilizers during seedling development,Phosphorus and potassium fertilizers need to be applied quantitatively and precisely during seedling development.In order to cultivate strong seedlings with high quality and efficiency,eight different fertilization ratios(N:P2O5:K2O/(kg/m3))were set up in this experiment using ’Zhongkan 15’cabbage variety and ’Kawasaki Hidemi’ pepper variety as test materials,namely:CK(0.00:0.00:0.00);T1(0.00:0.60:0.60);T2(0.60:0.00:0.60);T3(0.60:0.60:0.00);T4(0.15:0.60:0.60);T5(0.30:0.60:0.60);T6(0.45:0.60:0.60);T7(0.60:0.60:0.60),to study the effects of different fertilization treatments on the growth and development,photosynthetic characteristics and the content and accumulation of nitrogen,phosphorus and potassium nutrients in different tissues and organs of cabbage and pepper plug seedlings,with the goal of clarifying the nutritional requirements of nitrogen,phosphorus,and potassium in cabbage and pepper seedlings,with a view to providing a basis for establishing a set of safe,green,efficient and economic fertilization methods for cabbage and pepper seedlings.The principal results were as follows.:(1)PK fertilization increased cabbage plant height by 9.05%compared with CK after 28 d of seedling emergence;stem thickness increased by 0.54%to 5.28%compared with CK in the same period.In the six treatments with N fertilizer,cabbage plant height increased by 11.64%to 34.48%compared with CK;stem thickness increased by 1.02%to 20.37%compared with CK in the same period.In the six treatments with N fertilizer,the plant height of pepper cavity seedlings increased by 34.88%～85.43%and the stem thickness increased by 30.06%～43.41%compared with CK in the same period.(2)Compared with CK,NPK fertilization(T6 and T7)increased root,stem,and leaf N content of cabbage cavity pan seedlings by up to 1.16,1.27,and 0.99 times;NP fertilization increased root,stem,and leaf phosphorus content of cabbage cavity pan seedlings by up to 89.19%,69.62%,and 48.62%;NK fertilization increased root,stem,and leaf potassium content of cabbage cavity pan seedlings by The root,stem and leaf potassium contents of cabbage cavity seedlings increased by 21.99%～122.13%,9%～46.69%and 7.79%～35.88%with NK fertilizer.The application of sufficient NPK fertilizer(T6 and T7)increased the N content of roots,stems and leaves of pepper cavity tray seedlings by up to 1.08,3.2 and 3.57 times;the application of PK fertilizer promoted the phosphorus content of leaves of pepper cavity tray seedlings by 24.29%～113.12%.(3)The cumulative total nitrogen,total phosphorus,and total potassium in cabbage plants ranged from 0.268 to 4.264 mg/plant,0.214 to 2.948 mg/plant,and 1.241 to 19.731 mg/plant;in pepper plants,the cumulative total nitrogen,total phosphorus,and total potassium ranged from 0.258 to 17.657 mg/plant,and 0.15 to 4.468 mg/plant.The accumulation of nitrogen,phosphorus and potassium was mainly concentrated on the leaves,where the accumulation of nitrogen in cabbage cavity tray seedlings accounted for 85%-89%,phosphorus 58.54%-81.91%and potassium 45.07-82.37%;the accumulation of nitrogen in pepper cavity tray seedlings accounted for 43.8%-80.65%and phosphorus 80.65%.The accumulation of N in the leaves of pepper cavity seedlings ranged from 43.8%to 80.65%,phosphorus from 49.77%to 77.62%,and potassium from 28.89%to 77.21%.(4)After PK fertilizer application,the proportion of nitrogen requirement of cabbage seedlings increased by 3%-16.8%,phosphorus requirement increased by 18%-62%,and potassium requirement increased by 13.44%-49.14%;with NK and NP fertilizers,the proportion of nitrogen requirement of cabbage seedlings increased by 47.05%-189%and 41.67%-99%,phosphorus requirement increased by 23%-69%and 32.29%-99%,and potassium requirement increased by 58.62%.The N,P and K requirements of cabbage cavity seedlings increased by a maximum of 241%,311%and 124.56%with NPK fertilization.With PK fertilizer,the percentage of N requirement of pepper cavity seedlings increased by 8.56%to 58.26%(decreased by 2.17%at 28 d of emergence),phosphorus requirement increased by 27%to 146%,and potassium requirement increased by 22.94%to 41.43%;with NK and NP fertilizer,the percentage of N requirement of pepper cavity seedlings increased by 190.57%to 576%and 210.47 to 580.87%,and the percentage of phosphorus requirement increased by 91%to 176%and 5%.NPK and NP fertilizers increased the N requirement of pepper cavity seedlings by 190.57%～576%and 210.47～580.87%,phosphorus requirement by 91%～176%and 5%～391%,and potassium requirement by 95.66%～218%and 15.22%-100%;the maximum increase of pepper cavity seedlings was 8.61,9.41 and 5.3 times with NPK fertilizer.(5)Ternary quadratic regression analysis was conducted with urea,calcium superphosphate,and potassium sulfate application rates as independent variables and cabbage cavity tray seedling strength index at different periods as dependent variables,and the optimal rates of N,P2O5,and K2O for cabbage cavity tray seedlings were obtained as 0.43-0.69 kg/m3 for N,0.34-0.70 kg/m3 for P2O5,and 0.46-0.68 kg/m3 for K2O,the optimal dosages of N,P2O5 and K2O for pepper cavity tray seedlings were 0.61-0.69 kg/m3 for N,0.38-0.69 kg/m3 for P2O5 and 0.65-0.68 kg/m3 for K2O.(6)After the application of N fertilizer(T2～T7)treatments,the substrate N content of pepper cavity tray seedlings increased up to 2.44 times compared with CK in the same period;the substrate fast-acting N increased up to 27 and 11.42 times compared with CK in the same period.The total phosphorus content of the substrate increased 0.05-0.8,0.21-0.47,1.98-4.45,0.13-0.45,and 0.27-0.79 times,respectively,for each treatment of P fertilizer(T1,T3～T7);the substrate fast-acting phosphorus content increased 1.468.22 and 1.38-5.45 times,respectively.After the application of K fertilizer,the basal potassium content of T1,T2 and T4-T7 treatments were higher than that of T3;the quick-acting potassium content of T1,T2 and T4～T7 treatments were significantly higher than that of CK and T3 treatments.(7)Application of N and K fertilizers(T2,T4～T7 treatments)showed significantly higher urease activity than CK at all periods;more abundant N and P fertilizers increased the sucrase activity in the substrate;after 28 d of seedling emergence,the phosphatase activity was significantly higher in the treatments with N fertilizers(T2～T7)than CK;more abundant use of NPK fertilizers increased the substrate peroxidase activity. |
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