Effect of drought stress on yield and yield components of sunflower (Helianthus annuuss) at different plant densities

Effect of drought stress on yield components of two sunflower (Helianthus annuuss) hybrids at different plant densities was investigated. The experiment was conducted as a split factorial based on Randomized Complete Block Design with three replicates at Research Station of the Islamic Azad University of Tabriz in 2006. Treatments were varieties, four levels of water including control, 75%, 50%, 25% of available soil moisture and plant densities at 80, 90 and 100 thousands plants per hectare, Row spacing was 60 cm and plant interval 16, 18 and 20 cm, respectively for the three plant densities Results indicated that application of the drought stress had a significant decline in hundred seed weight, oil percentage, grain and oil yield per hectare (P