Asian Journal of Biological Sciences1996-3351xxxx-xxxxScience International10.3923/ajbs.2009.35.42AbbasiA. TobehA. Shiri-e-JanagradM. Jamaati-e-SomarinSh. HassanzadehM. HokmalipourS. 2200922In order to evaluate responses of two potato cultivars to different nitrogen levels, a split-plot design based on randomized complete block design with four replications was conducted at agricultural research field, Ardabil, Iran in 2008. Main-plots included nitrogen levels: 0, 80, 160 and 200 kg ha-1 nitrogen and sub-plots were assigned to Agria and Satina cultivars. Measured traits were mean tuber weight, tuber yield and number of tuber were sorted according to size and harvest index. Results showed that cultivar Agria in all traits was superior to Satina except for the number of small size tubers. The highest mean tuber weight and tuber yield was observed using 160 and 200 kg ha-1 nitrogen. With increasing nitrogen levels, number of tubers larger than 55 mm was increased. The rate of 160 kg ha-1 nitrogen resulted in the tubers ranged between 28 and 55 mm. Agria cultivar gained more leaf biomass during the season than Satina cultivar 160 kg ha-1, N produced the highest and control, produced the lowest biomass, respectively. The highest leaf biomass was obtained 83 DAP and finally decreased because of senescence and falling of leaves. Impact of nitrogen was not significant on small size tubers. Also, cultivar Agria had the highest values for most traits in treatment of 160 kg ha-1 nitrogen.]]>Ankumah, R.O., V. Khan, K. Mwamba and K. Kpomblekou,2003100201207Beraga, L. and K. Caeser,1990Solanum tuberesom L. cv. erntestolz) as influenced by different day length.]]>33257267Carter, J.N. and S.M. Bosma, 197466263266Cole, C.S.,1975182837Jamaati-e-Somarin, S., A. Tobeh, M. Hassanzadeh, M. Saeidi, A. Gholizadeh and R. Zabihi-e-Mahmoodabad,20081119491952Jamaati-e-Somarin, S., A. Tobeh, M. Hassanzadeh, S. Hokmalipour and R. Zabihi-e-Mahmoodabad,20093122126Jenkins, P.D. and D.G. Nelson,199235127132Khajehpour, M.,20062nd Edn.,pp: 580pp: 580Kleinhenz, M.D. and M.A. Bennet,1992Solanum tuberosum L.) cultivars Atlantic and Monona as influenced by seed type and size.]]>69117129Love, S.L., J.C. Stark and T. Salaiz,2005822130Osaki, M., H. Ueda, T. Shinano, H. Matsui and T. Tadano,199541557566Jackson, S.D.,199911918Struik, P.C., A.J. Havercort, D. Vreugdenhil, C.B. Bus and R. Dankerts,199033417432Vos, J.,1995Solanum tuberosum L.).]]>38271279Zrust, J. and M. Juzl,199642293300