Effect of drought stress and potassium sulfate on yield and yield components of sunflower

In ordsr to study yield and some physiologic characteristics of sunflower (cv. Euroflor) in reaction to water and potassium applying, a RCBD base split plot experiment was conducted in 2009 at Islamic Azad University- Tabriz branch research farm. Water deficite stress at four levels (50, 90, 130 and 170 mm evaporate from class A pan) arranged in main plots and five K2SO4 levels (0, 50, 100, 150 and 200 kg/ha) in sub plots. The results of variance analyzing of date showed that interaction of stress and K was highly significant on height of stem, leaf dry weight, number of grain in anthodium¸ weight of grain in anthodium, biomass, yield¸ harvest index and 100 kernel weight, effective filling period was significant. Result showed that the interaction effects of treatments had significant different in these traits. Rate of a traits under study increased when 200 kg/ha of potassium sulphate was used and field irrigated after 50 mm evaporation from pan. Application of potassium decrease drought stress damage. Irrigating after 50 to 90¸ 130 and 170 mm evaporation from pan decreased yield by 10.36¸ 24.43 and 59.46 percent. But yield reduction by application 200 kg/ha potassium sulfate fertilizer was only 32.48 percent. This indicates that by applying potassium fertilize yield reduction will be decreased under drought stress.