Evaluation of leaf analysis as an index for judging nitrogen needs of four potato cultivars in Shimla hills

Field study was undertaken on slightly acidic soil of Shimla (Palehumults) with four potato cultivars to study the effect of N application on leaf composition at various growth stages and to work out critical limits for NO₃-N (petioles) and total N (leaf blades). Potato cultivars did not differ significantly among themselves with regard to nutrient content in leaves and petioles at 75., 95 and 115 DAP. N application significantly increased NO₃-N (petioles) and total N (leaf blades) but decreased K content. Both NO₃-N in petioles and total N in leaf blades showed a curvilinear relationship with final tuber yield and correlation coefficients were significant in early growth stages.