Effect Of Potassium Fertilizer Application By Stages On Sweet Potato Production

The split application of potassium fertilizer is one of the important technical measures to improve the yield and quality of sweet potato.In this experiment,Starch Sweet Potato Varieties Jishu 25 and Luxuan No.1 were used as experimental materials,and all of them were applied with potassium fertilizer at the bottom（K1）,60 days after transplanting（K2）,80 days after transplanting（K3）and 100 days after transplanting（K4）,the test results are as follows.1.The period of potassium application had significant effect on nutrient accumulation,absorption and utilization of sweet potato.The accumulation of N,P and above-ground K in sweet potato could be promoted by delaying the application of K fertilizer.The accumulation of N and P in Jishu 25 was the highest at 100 days after transplanting,potassium accumulation was the highest in the plants treated with one-time bottom application of potassium fertilizer.The highest accumulation of N,P and K appeared at 60 days after transplanting,while the highest accumulation of k appeared at 80 days after transplanting.The absorption and utilization of nutrients in Jishu 25 was higher in single application of potassium fertilizer at the bottom,while the absorption and utilization of nutrients in Luxuan No.1 was higher in topdressing application of potassium fertilizer at 80 days after transplanting.2.The dry matter accumulation of two varieties of sweet potato was faster in the early growth stage,slower in the late growth stage,and the t/r value decreased rapidly with the advancing of the growth stage.Treatment K1 of Jishu 25 and treatment K3of Luxuan 1 had the lowest t/r value and the highest dry matter accumulation among the treatments.3.The effect of potassium application stage on yield and yield characters of sweet potato was significant.K1 had the highest weight per plant and yield of38250kg hm^-2,while Luxuan No.1 had the highest yield of 58012.5 kg hm^-2,and K3had the highest yield of 58012.5 kg hm^-2.The percentage of large and medium tubers decreased with the delay of potassium application.4.The application of potassium fertilizer by stages has significant effect on the quality of Sweet Potato Starch.The highest starch content of Jishu 25 was treated with K4,and that of Luxuan No.1 was treated with K2.The K4 treatment viscosity and gelatinization enthalpy of Jishu 25 were the highest,and the K1 treatment was the best among the starch quality traits,while the K2 treatment was the best among the three treatments,the enthalpy of gelatinization was highest with K3 treatment.