Potato being a short duration crop, fits very well in rice based cropping system even under Terai Agro-Climatic situation of West Bengal, India where winter is prolonged and kharif rice is harvested even in mid December in low lying situation. There are many factors, which effect the potato production under delayed planting condition, however, nitrogen nutrition is of out most importance. Inadequate use of nitrogen decreases potato yield by decreasing plant growth characters. On the contrary, excess nitrogen may also hinder its yield by reducing translocation of photosynthates from top to bottom. Mr.Debadis Mahata conducted an experiment in a Randomized Block Design with eight different levels of nitrogen: 75 Kg N /ha (T1), 90 Kg N /ha (T2), 105 Kg N /ha (T3), 120 Kg N /ha (T4), 135 Kg N /ha (T5), 150 Kg N /ha (T6), 165 Kg N /ha (T7) and 180 Kg N /ha (T8) to study the effect of different levels of Nitrogen on Net Photosynthesis Rate, Stomatal Conductance Rate, Transpiration Rate and economics of potato cultivation and recommended the right dose of nitrogen for Terai agro-climatic region of West Bengal.