Vol. 20, No. 2 GOSWAMI et al 105 Journal of Agrometeorology 20 (2) : 105-109 (June 2018) Potato is the most important non-grain field crop with a global production of 501 million tonnes in 2014 (FAO, 2014). However, potato production is likely to decline across many parts of the world by 2100 (Raymundo et al. , 2014). But, Stockle et al. (2010) indicated that, taking into account the positive effect of CO 2 and adaptation strategies on crop production might sustain the current production levels under future climate change conditions.The SUBSTOR-Potato model has been used extensively to evaluate effects of variability in climate (Patil et al ., 2018) nitrogen (Snapp and Fortuna, 2003) and water (Malkia et al. , 2016) for optimizing potato productivity and also for climate change studies (Franke et al ., 2013). IPCC (2013) projected the global temperature change based on various Representative Concentration Pathways (RCP). Their assessment suggests that the temperature change at the end of the 21 st century is likely to exceed 1.5°C relative to 1850-1900, for all RCP scenarios except RCP 2.6. Ravindranath et al. (2011) assessed the effects of climate change in the North East India with multiple socio-economic consequences and opined that since 80 per cent of the crop area is under rainfed agriculture in the region, present and future climate change and variability might potentially affect agriculture production here, by virtue of acute soil moisture deficit and lack of irrigation/water harvesting infrastructure. A study, based on standardized precipitation index, demonstrated the changes in overall seasonal proneness of the North East India to meteorological drying or wetting, and that most places of the region had suffered loss of monsoon wetness during 1991-2007 (Saikia et al. ,2013). At Jorhat, Assam increase in both maximum and minimum temperatures, under different RCPs for 2020, 2050 and 2080, suggested increasing level of heat stress during crop growth period (Goswami et al. , 2016). Under these circumstances, this study was taken up to evaluate the impact of climate change on potato production in Assam, which is a major potato growing area in the state. MATERIALS AND METHODS Field experiment The field experiment was conducted at Jorhat, Assam (26°44´N latitude, 94°l0´E longitude and 9l m above mean sea level),respectively during rabi seasons of 2014-15 and 2015-16 in a sandy clay loam soil (Table 1) with three cultivars of potato, viz ., (Kufri Jyoti, Kufri Pokhraj and Kufri Himalini ) and three dates of planting at 15 days interval (20 November, 6 and 22 December in 2014-15 and 19 November, 5 and 21 December in 2015-16) in a randomized Impact assessment of climate change on potato productivity in Assam using SUBSTOR-Potato model B. GOSWAMI 1 , R. HUSSAIN 1 , P.V. KUMAR 2 , U.S. SAIKIA 3 * and S. BANARJEE 4 1 Department of Agricultural Meteorology, AAU, Jorhat 785 013, Assam 2 Central Research Institute for Dryland Agriculture, Hyderabad 500 059 3 ICAR Research Complex for NEH Region, Umroi Road, Umiam 793 103, Meghalaya 4 Bidhan Chandra Krishi Viswa Vidyalaya, Kalyani 741 235, West Bengal *Email: ussaikia73@gmail.com ABSTRACT Potato tuber yield were simulated at Jorhat, Assam under various Representative Concentration Pathways (RCPs) scenarios for 2020, 2050 and 2080 using DSSAT SUBSTOR-Potato model. The model was calibrated and validated for three potato cultivars, viz., Kufri Jyoti, Kufri Pokhraj and Kufri Himalini with the experimental data collected during 2014-15 and 2015-16. Results revealed that if planting is delayed beyond November, all these cultivars are likely to record drastic reduction in tuber yield. Cultivar Kufri Himalini may incur tuber yield loss of 64 per cent in 2020 to 75 per cent in 2080, followed by Kufri Jyoti (57.6% in 2020 to 71.5% in 2080) and Kufri Pokhraj (45.2% in 2020 to 56.2% in 2080). Among the cultivars, Kufri Pokhraj may remain a viable cultivar up to 2050, but Kufri Himalini may lose its sustainability by 2020 itself. Hence, adjustment of planting time and development of improved adaptive potato cultivars only will ascertain future potato production in this region. Key words: Climate change, RCP, potato yield variability, DSSAT SUBSTOR-Potato model