اثر تغييرات ضريب تخليه مجاز رطوبتي خاك بر كميت محصول پنبه در منطقه گرگان

The effect of soil moisture allowed depletion on in gorgan cotton yield

in order to determine the cotton irrigation time based on soil moisture allowed depletion and the effect on cotton quantity of siokra and 818-312 varieties, an experiment was conducted in 1999 and 2000 in a silty clay loam soil in Hashemabad Cotton Research Station as split plot with completely randomized blocks comparing four treatments and three replications. Irrigation treatments were: lrrigtion after depletion of 40% , 60% and 80% of soil available moisture during growing season in every irrigation and the other 40% depletion before flowering and 60% after flowering. The results showed that the effect of irrigation treatments were not significant on total yield and boll weight in every years, but on earliness was only significant in the first year. The highest yield was in siokra variety that 818-312 was increased 11.7% and 5.6% in two years, respectively and its difference was only significant in the first year. The results of complex analysis showed that there wasnʹt significant difference on totally yield of years but it was on earliness. Irrigation treatments were not different in view of yield and earliness. The higher yield in two years with 3592 kg/ha belong to siokra that increased 10.2% than 818-312 and 818-3 12 was the more earliness. Ultimately the best irrigation treatment in view of management and decreasing of irrigation numbers were 80% soil moisture allowed depletion and the best variety was siokra.