Optimized Cultivation of Starch-rich Sweet Potato, Rongshu 819, on Hilly Land

Effects of transplanting density and applications of nitrogen, phosphorus and potassium fertilizers for the starch-rich sweet potato, Rongshu 819, on hilly land were studied for cultivation optimization. An orthogonal experiment by a quadratic, orthogonal and pivoting regression for 4 factors was conducted. The results showed that (1) the effects of 4 factors on the tuber yield were in the order of potassium > phosphorus > transplanting density > nitrogen; and (2) the highest yield of fresh sweet potatoes above 37.500 t·hm^-2 could be achieved by using the transplanting density ranging 46 260-50 108 plants·hm^-2 with the fertilization of pure nitrogen at a rate of 0.081-0.107 t·hm^-2, P₂O₅ at 0.061-0.092 t·hm^-2 and K₂O at 0.303-0.329 t·hm^-2.