Anionic balance of nitrogen, phosphorus and sulphur in Potato leaves under rainfed conditions in Shimla hills

Studies conducted on acidic soils of Fagu (Shimla) revealed a synergistic effect of N on P and S concentrations in potato leaf at stolon formation and tuber initiation stage but antagonistic effect of higher levels of P and S on the bio-anions concentration. The triangular model showed that critical concentrations of N and P in leaves at threshold, economic and optimum level of fertilizers application of N, P and S decreased with time while that of S increased. Likewise, both P:S and N:S ratios in leaves were higher at stolon formation as compared to tuber initiation stage. The critical N:P:S ratio in leaves at stolon formation stage was 15.78:1.37:1.00 which narrowed to 12.87:0.65:1.00 at tuber initiation stage.