N Save Nature to Survive 12(1): 503-506, 2017 (Supplement on Agronomy) www.thebioscan.com 503 EFFECT OF PHOTOPERIODS, GENOTYPES AND THEIR EFFECT OF PHOTOPERIODS, GENOTYPES AND THEIR EFFECT OF PHOTOPERIODS, GENOTYPES AND THEIR EFFECT OF PHOTOPERIODS, GENOTYPES AND THEIR EFFECT OF PHOTOPERIODS, GENOTYPES AND THEIR INTERA INTERA INTERA INTERA INTERACTIONS ON QU CTIONS ON QU CTIONS ON QU CTIONS ON QU CTIONS ON QUALITY TRAITS OF POT ALITY TRAITS OF POT ALITY TRAITS OF POT ALITY TRAITS OF POT ALITY TRAITS OF POTATO (SOLANUM TO (SOLANUM TO (SOLANUM TO (SOLANUM TO (SOLANUM TUBEROSUM L.) TUBEROSUM L.) TUBEROSUM L.) TUBEROSUM L.) TUBEROSUM L.) RAVI SHANKAR 1 , DHIRENDRA SINGH 1 , JITENDRA KUMAR 2* AND ANKIT PANCHBHAIYA 1 1 Department of Vegetable Science, 2 Department of Horticulture, College of Agriculture, Govind Ballabh Pant University of Agriculture and Technology Pantnagar - 263 145 (INDIA) e-mail: jkumar_hort@outlook.com INTRODUCTION The potato (Solanum tuberosum L.) is a vegetable crop of major economic importance worldwide. It is the fourth most cultivated food crop after wheat, rice and maize (Jones et al., 1994). Potato is used as vegetable, stock feed and in industries for manufacturing starch, alcoholic beverages and other processed products. It is an important temperate crop which has been adopted well for cultivation under sub-tropical conditions. It is a starchy, tuberous crop from the perennial genus Solanum of the Solanaceae family. Potato is an integral part of human diet. It produces more protein (524 kg/ha) as compared to wheat (254 kg/ha) (Sazid and Aftab, 2009). Potato tubers contain about 80 per cent water and the rest is dry matter. Starch is the major component of the dry matter accounting approximately 70 per cent of the total solids. Potato is a cheap source of energy and good supplier in relation to requirement of dietary nitrogen of high quality and was pre- eminent as a source of vitamin C, vitamin B, high dry matter, mineral and carbohydrates per unit area (Gopalan et al., 1972).The average raw material composition of a potato tuber is as dry matter (20%), starch (13-16%), total sugars (0-2%), protein (2%), fibre (0.5%), lipids (0.1%), vitamin C (31 mg/ 100 g fresh weight), minerals (trace), ash (1-1.5%), and amylase (22-25%). Two major environmental factors that control development of potato are temperature and photoperiod. These factors are represented in crop development simulation models by temperature and photoperiod response functions. Potato is a short-day plant for tuber initiation and long-day or neutral plants for flowering, i.e. short-days accelerate tuber initiation and delay flowering (Van Dam et al ., 1996). Photoperiod response in potato is dependent on genotype and on developmental phases (Kooman et al., 1996). Dories et al. (1995) observed that Sweet pepper could also benefit from an extended light period. Under continuous photoperiod, the photosynthetic rate was higher and more photo assimilates were translocated to the fruit. Diurnal translocation rates were 2 to 3 times higher under 18h and 24h photoperiod than 12h lighting and linear relationship between translocation rate and photosynthetic rate was observed. Stutte et al. (1996) found that in potato plants grown under 24h photoperiod, photosynthesis was 33% lower than in plants grown under 12h photoperiod. Therefore, the present study was conducted to assess the effects of photoperiod on quality traits of different potato genotypes. MATERIALS AND METHODS The experiment was conducted at Vegetable Research Centre of Govind Ballabh Pant University of Agriculture and Technology Pantnagar, District Udham Singh Nagar, Uttarakhand during rabi season of 2012-13. Geographically, Pantnagar situated at 29.5ºN latitude, 79.3º E longitude and having an altitude of 243.8 meters above the mean sea level ABSTRACT Present study was conducted at G.B. Pant University of Agriculture and Technology Pantnagar during rabi season to determine the relationship between photoperiod and potato genotypes with respect to quality. Study showed significant differences among genotypes, photoperiods and their interactions for total soluble solids (TSS), protein and ascorbic acid content. In case of dry matter and specific gravity, effects of genotypes and photoperiods were found to be significant but their interactions between them showed non-significance. Differences in the entire traits between two photoperiods P 1 and P 2 were found significant. Mean values for different traits revealed that plant under extended photoperiod have shown maximum TSS (5.27%), dry matter (18.77%), specific gravity (1.35 g/cm 3 ), protein (1.46%) and ascorbic acid (4.97mg/100g) content. Among all the interactions between photoperiods and genotypes both Kufri Chipsona-2 and Kufri Chipsona-3 under extended (22.50 and 22.00%, respectively) and normal (20.63 and 20.56%, respectively) photoperiod gave better results in comparison to other interactions. For protein content, among all the interactions genotypes C-15, EM-1, AICRP-08-2 under extended photoperiod and Kufri Bahar under normal photoperiod were better than other interactions. The mean values of above interactions were 1.80, 1.76, 1.69 and 1.68%, respectively. Most of the quality traits were better under extended photoperiod. KEYWORDS Photoperiod Potato Genotype Quality Received on : 00.00.2016 Accepted on : 00.00.2017 *Corresponding author