Studying the effect of drought stress on yield and yield components of three sunflower cultivars

To investigate the effects of water deficit stress on some morphological traits of three sunflower cultivars, a split plot experiment based on randomized complete block design was conducted with three replications during 2007 growing season at Agricultural Research Station of Tabriz Azad University. Water deficit at five levels (50 as control, 100, 150, 200 and 250 mm from class A evaporation pan) was assigned to main- plots and three cultivars (Aramvirsky, Allstar and Euroflour) were considered as sub-plots. Results showed that seed yields produced under 100, 150, 200 and 250 mm evaporation from the pan were 78%, 65%, 50% and 43% of the control seed yield, respectively. Among the studied cultivars 'Armavirsky' produced greater yield than 'Allstar', but 'Euroflour' did not show significant differences with the two other cultivars. Increasing water deficit stress significantly decreased seed yield and oil percentage. The interaction effect between water deficit stress and cultivar was significant on percentage of unfilled grain and filled grain.