Determination of the suitable plant density and planting date for new hybrid (CMS-26 R-103) of sunflower (Helianthus annuus L.)

In order to determining the suitable planting date and planting density for new hybrid (Cms-26 ´ R-103) of sunflower, an experiment was conduct in Karaj, Iran in 2006 and 2007 cropping seasons, using split plot arrangement in a complete randomized block design with four replications. Two factors of planting date in four levels (9 May, 30 May, 20 June and 11 July) in main plots and plant density in four levels (6, 8, 10, 12 plant/m2) in subplots. The results showed that the effect of year on all traits was not significant. Planting date significantly affected all of measured traits except productivity index. The highest grain yield was achieved in the first planting date (i.e. 9 May) with 3540 kg/ha. The results also showed that the effect of plant density was significant on all traits (p<0.01), except 1000 grain weight and productivity index. Interaction of planting date ´ plant density was negligible on all studied traits except grain yield, total grain no. per m2 and number of filled grain /m2. The first planting date (i.e. 9 May) with 12 plants/m2 and the latest planting date (i.e. 11 July) with 6 plants/m2 produced the highest yield (4200 kg/ha) and the least grain yield (1430 kg/ha), respectively. The results revealed that planting dates from 9 May to 30 May with 12 plants per m2 were the most suitable combinations for obtaining the highest grain yield in sunflower new hybrid (CMS-26 ´ R-103).