چكيده لاتين :
Drought stress is one of the most important abiotic stresses influencing performance of crop plants. Therefore, the identification or development of tolerant genotypes is of high importance for incorporating in cotton production. In this study to evaluate the effect of drought stress on some cotton traits , 5 improved cotton varieties were studied in a split plot design with three replications in 2 years (2000-200 I) at 2 locations (Hashemabad and Anbaroloom); one with Mediterranean climate
and the other with drought- stress condition. Treatments were irrigation as main plot in 3 levels (I upsilon=w ithout irrig ation, II=one time irrigation; that carried out 70 day s a fter sowing, and 12=at least 3
time s irrig ation) and varieties as subplot in 5 levels (5 genotypes) . In the bas is of combined variance an alysis significant di fferences were detected among varieties for yield, boll number, boll weight,
length and number of sympodial and monopodial branches. Drought stress decreased yield, boll number, boll weight , and induced earliness . With increasi ng irrig at ion frequency , earl iness lightly redu ced in the former climate probably because of indu cing vege ta tive growth and retarding in gene rative phase. In latter climate increased irrigation frequ en cy had a pos itive e ffect on the yield. It seems that water defi ciency has reduced yield via decreasing boll number. The number of formed
bolls in stress fulconditions was less than that of in non -stressful conditions. Stress tolerance inde x (STI ) reve aled that Siokra-324 and Tab ladila were more tolerant and stable varieties.
