N Save Nature to Survive 12(1): 515-519, 2017 (Supplement on Agronomy) www.thebioscan.com 515 EFFECT OF NITROGEN LEVELS ON YIELD EFFECT OF NITROGEN LEVELS ON YIELD EFFECT OF NITROGEN LEVELS ON YIELD EFFECT OF NITROGEN LEVELS ON YIELD EFFECT OF NITROGEN LEVELS ON YIELD, NITROGEN UPT , NITROGEN UPT , NITROGEN UPT , NITROGEN UPT , NITROGEN UPTAKE AKE AKE AKE AKE AND EFFICIENCY OF POT AND EFFICIENCY OF POT AND EFFICIENCY OF POT AND EFFICIENCY OF POT AND EFFICIENCY OF POTATO V TO V TO V TO V TO VARIETIES UNDER T ARIETIES UNDER T ARIETIES UNDER T ARIETIES UNDER T ARIETIES UNDER TARAI ARAI ARAI ARAI ARAI REGION OF UTT REGION OF UTT REGION OF UTT REGION OF UTT REGION OF UTTARAKHAND ARAKHAND ARAKHAND ARAKHAND ARAKHAND GIRISH CHANDRA*, MANOJ RAGHAV 1 , UDIT KUMAR 2 AND PANKAJ KUMAR 3 *Department of Life Science, SGRRITS, Patel Nagar, Dehradun - 248 001, Uttarakhand, INDIA 1 Department of Veg. Sci. GBPUA&T Pantnagar, U.S. Nagar, Uttarakhand, INDIA 2 Department of Hort., RPCAU, Pusa, Samastipur - 848 125, Bihar, INDIA 3 GPB, UUHF, CoF, Ranichauri, Tehri Garhwal, Uttarakhand, Pin - 249 199 e-mail:girishctiwari24@gmail.com INTRODUCTION Potato belongs to genetically diverse genus Solanum which contains about 2,000 species of which, 235 are tuber bearing species. It is rich source of carbohydrates, proteins, phosphorus, calcium, vitamin C and carotene (Reshi et al., 2013). It produces more protein (524 kg/ha) as compared to wheat (254 kg/ha) (Sajid and Aftab, 2009). Potato tuber contains about 80 % water and the rest is dry matter. Starch is the principal constituent of the dry matter accounting for approximately 70 % of the total solids (Lokendrajit et al., 2013). Potato is highly responsive to nitrogen nutrition and it is usually the most limiting essential nutrient for activity of potato growth and development. Nitrogen supply also plays an important role in the balance between vegetative and reproductive growth of potato plant. It is a vital nutrient for the activity of plant organs (Najm et al., 2013). Nitrogen uptake by potato crop is a function of yield potential and variety. The period of nitrogen uptake in potato plant begins about the time of rapid biomass accumulation and it is completed long before the crop reaches maturity. Nitrogen uptake on per day basis is some time even more than 1.5 kg/ ha when only active growth period is considered (Sullivan et al., 1999). It’s important, for two reasons, to know the nitrogen demand in potato crop. First is the excessive use of nitrogen nutrition increases economical cost and second is the negative effects on environments, as problems associated with leaching and runoff (Rahemi et al., 2005). The efficiency of nitrogen fertilizer management is influenced by many factors including source, form, placement, application rate and timing of the nitrogen fertilizer in addition to soil and environmental conditions. Nitrogen leaching is the primary mechanism for nitrogen loss in potato production (Zebarth and Rosen, 2007). Improved nitrogen fertilizer management will reduce the risk of NO 3 leaching and N 2 O emissions during the growing season and will also reduce residual soil nitrate at harvest. In humid environments, where significant NO 3 leaching and N 2 O emissions occur either before or after the crop growth period, reduced residual soil nitrate is an important factor in limiting environmental nitrogen losses (Cambouris et al., 2008). Thus keeping this in mind the present investigation was carried out to know the effect of nitrogen fertilizer on yield, nitrogen uptake and nitrogen use efficiency of potato varieties. MATERIALS AND METHODS The present investigation was undertaken at Vegetable Research Centre of G.B.P.U.A. and T. Pantnagar, Uttarakhand, during Rabi season of 2012-13 and 2013-14. The experiment consists of five levels of nitrogen fertilizer viz., 0 (N 0 ), 75 (N 1 ), 150 (N 2 ), 225 (N 3 ) and 300 kg/ha (N 4 ) and two variety viz. Kufri Sadabahar (V 1 ) and Kufri Surya (V 2 ), which were replicated thrice in factorial randomize block design. The half of the each level nitrogen apply as basal and remaining half amount top dressed after 30 days of planting. The source of nitrogen was urea (46% N). The potato crop was de-haulmed at 90 ABSTRACT In order to know the marketable yield and nitrogen use efficiency of potato, five nitrogen levels and two potato varieties were replicated thrice in the experiment at Vegetable Research Station, GBPUAT Pantanagar. It was observed from the study that variety Kufri Surya performs better than Kufri Sadabahar in relation to marketable yield, nitrogen uptake, nitrogen use efficiency and nitrogen apparent recovery. Maximum marketable yield (43.87 t/ha), nitrogen content in tuber (1.17 %) and total nitrogen uptake (193.94 kg/ha) were recorded with application of 150 kg N/ha (N 2 ), while nitrogen use efficiency (141.60 kg tuber/kg N) and nitrogen apparent recovery (67 %) were observed maximum with application of 75 kg N/ha (N 1 ). Interaction effect of variety Kufri Surya and 150 kg N/ha (V 2 N 2 ) gave maximum marketable tuber yield (45.75 t/ha) and total nitrogen uptake (199.05 kg/ha) among all treatments. The maximum nitrogen use efficiency was recorded (152.80 kg tuber/kg N) with treatment combination V 2 N 1 . It can be concluded that the variety Kufri Surya with application of 150 kg/ha nitrogen was best among all other treatments for potato production. KEYWORDS Potato tuber nitrogen variety Received on : 10.04.2016 Accepted on : 06.02.2017 *Corresponding author