چكيده لاتين :
This experiment was conducted in Sadough Salinity Research Farm subordinating to National Salinity Research Center (NSRC) in two years during 2003 and 2004 in order to determinate of threshold values in cotton (Gossypium hirsutum L.) cultivars to salt tolerance. Treatments were saline water (main plots) in four levels: 2 (control), 6, 10 and 14 dS/m and subplots were cotton cultivars in three levels: Varamin, Bakhteghan and Siokra. Soil salinity (ECe) in root zone determined by soil sampling during of growth season, orderly and variation of relative yield (Yr) to ECe investigate with linear and sigmoidial models. Therefore, salinity threshold values for Varamin, Bakhteghan and Siokra cultivars obtained 4.1, 4.8 and 5.0 dS/m, upon linear model and in sigmoidial model C50 obtained for above varieties 12.05, 13.31 and 12.56 dS/m respectively. The effect of saline water treatments on yield was significant in %5 probability, so that, the highest yield produced in control treatment with 1834.0 kg.ha 1 and 6, 10 and 14dS/m treatments produced %9.5, %34.1 and % 58.9 less yield than control, respectively.
