The potato (Solanum tuberosum L.) is an important crop in moderate to cold regions, producing high yields of nutritionally valuable food in the form of tubers. In the cold steppe of the North West of Iran, nutrient management is a crucial component for successful potato production. This study was conducted to determine the effect of different fertilizers on growth, phenological development, tuber yield and tuber qualitative characteristics in two potato cultivars (‘Agria’ and ‘Spirit’). Specific objectives were to assess the effects of nanofertilizers on potato. Fertilizer treatments included: T1 – control (no fertilizer application), T2 – N-P-K chemical bulk fertilizer, T3 – MOG enzymatic bio-fertilizer, T4 – nano-chelated calcium, T5 – nano-chelated zinc+boron and T6 – nano-chelated complete fertilizer. The results indicated that application of nano-chelated Zn+B, complete nanofertilizer and chemical bulk N-P-K significantly increased plant height, the number of stems, main stem diameter and the number of leaves, and also accelerated the row closure (canopy closure). Application of nanofertilizer noticeably decreased the number of days to the initiation of tuberization. The evaluation of tuber yield components revealed that the highest numbers of tuber per plant, mean tuber weight, tuber weight per plant and harvest index were obtained by application of complete nanofertilizer. Comparisons of the cultivars indicated that ‘Agria’ was more responsive than ‘Spirit’ to nutrient managements and showed a more acceptable performance. Nutrient managements significantly affected the qualitative characteristics of tuber; so that the highest dry matter, starch and protein content was recorded for plant grown by complete nanofertilizer. The results of the present experiment agreed with the conclusion that balanced plant nutrition through the efficient nanofertilizers can improve potato productivity. Maintaining soil fertility through an adequate, suitable and balanced nutrien
