Effect of ray flower deleting on the unfilled grain and yield of two sunflower cultivars (Helianthas annuus L.)

In order to evaluate the effect of deleting of ray flower on the unfilled grain and seed formation, two cultivars of sunflower (Helianthus annuus L.) were used during 2008-2009 growing season in the research field of Kerman University. The experiment was conducted as factorial under RCBD. The main and sub factors were cultivars (two levels, Master and Euroflower), respectively and deleting ray flower (three levels, 0%, 50%, 100%) percentage of unfilled grain in the center of the head, number of unfilled grain around the head, weight of one thousand seeds, diameter of the head and yield. The combined results of two years study showed that there is significant difference between ray flower deleting treatment and cultivars related to percentage of unfilled grain at the center of head and yield. The Linear regression analysis was revealed a positive effect of deleting of ray flower on the recorded characteristic at the center of head and yield. Deleting 100% of ray flower deleting led to 307 and 201kg/ha yield of Euroflower cultivar in the first and second growing season. Also the yield of Master cultivar was calculated as 429 and 476 kg/ha in the first and second growing season, respectively.