A Study About Drought Stress Effects on Grain Yield Components of Three Sunflower Cultivars

In order to investigate the effects of drought stress on grain yield and its components, a study was carried out (2011) as split plots in randomized complete blocks design in Isfahan (32° 40'  N,51° 48' E). Main factor was drought stress in four levels including irrigation after 80, 100, 120, and 140 mm evaporation from evaporation pan (class A) and subplots were three cultivars (Sirena, Record, and Euroflore).Grain number per capitulum, 1000 grains weight, grain yield, biological yield, harvest index, oil percentage, and oil yield were measured. Results showed that by increasing the stress from 80 to 140 mm, all traits except oil percentage were decreased. The first irrigation treatment (80mm) seems to be the most appropriate treatment for this plant considering the highest grain and oil yields. Record cultivar produced the highest yield under 80 and 100 mm treatments while Sirena and Euroflore had the highest yields under 120 and 140mm treatments, respectively. Therefore, cultivating record will be better under drought stress or dry farming cultivation.