Research Journal of Environmental Sciences1819-34122152-8238Academic Journals Inc.10.3923/rjes.2014.109.116BazgeerS. FadaviGh. HossainyS.M. 2201482Because the climatic factors are largely uncontrolled, the variables that influence crop production must be quantitatively evaluated if we want to explain adequately the effects of any climatic variable on cotton growth stages. Cotton (Gossypium hirsutum L.) is a major row crop grown primarily for fiber and seed. The objective of this investigation was to develop Agroclimatic-Yield based regression models for estimation rain-fed cotton for Gharakhil district (Mazandaran Province, Iran) using available historical data. Twenty-Seven years (from 1985 to 2011) historical cotton yield data published by Gharakhil Agromet. Station (GAS) was related to climatological variables and agroclimatological indices to develop Agroclimate-Yield models. On the basis of correlation coefficient, F-statistics, standard error of estimate (r = 0.455, F = 4.431, SEOE = 894 kg ha^{-1} for Logarithmic regression model and r= 0.722, F= 5.456, SEOE= 739 kg ha^{-1} for Cubic regression model) and relative deviation (RD) of the selected years, the suitable time of estimation for cotton yield was found to be at the end of squaring stage i.e., July 19th (3 months before harvesting) using climatological and agroclimatological data/indices of the squaring stage (from June 28th to July 19th). The best agroclimatic subset were selected as Temperature Difference (TD) for Logarithmic and Rainfall (R) for Cubic model.]]>Abbate, P.E., J.L. Dardanelli, M.G. Cantarero, M. Maturano, R.J.M. Melchiori and E.E. Suero,2004Ghaderi, F.A., A. Soltani, E. Zainali and P. Rezaee,2006Bazgeer, S., R.K. Mahey, P.K. Sharma, A. Sood and S.S. Sidhu,2006Bauer, A., A.B. Frank and A.L. Black,1984Boyer, J.S.,1982Cull, P.O., A.B. Hearn and R.C.G. Smith,1981Doorenbos, J. and W.O. Pritt,1984FAO,2012Guinn, G.,1998Hundal, S.S., R. Singh and L.K. Dhaliwal,1997Triticum aestivum) in Punjab.]]>Kerby, T.A., M. Keeley and S. Johnson,1987Lomas, J., M. Mandel and Z. Zemel,1977Mauney, J.R.,1986Meena, R.P. and A.K. Dahama,2004Arachis hypogaea L.) during different phenophases under irrigated condition of Western Rajasthan.]]>Nuttonson, M.Y.,1955Pettigrew, W.T.,2004Rao, G.S.L.H.V.P.,2003Reddy, T.Y. and G.H.S. Reddi,2003Reddy, K.R., V.R. Reddy and H.F. Hodges,1992Reddy, K.R., H.F. Hodges, J.M. McKinion and G.W. Wall,1992Reddy, R.K.,1996Sawan, Z.M., L.I. Hanna, G.A. Gad El Karim and W.L. McCuistion,2002Gossypium barbadense).]]>Silvertooth, J.C.,2001Singh, V., C.K. Pallaghy and D. Singh,2006Stoilova, A. and G. Nikolov,2000Waddle, B.A.,1984Yeates, S.J., G.A. Constable and T. McCumstie,2010