Effects of planting date on growth indexes and grain yield of sunflower (Helianthus annuus L.) cultivars in dry conditions

In each plant، planting date is the research priorities and in rainfed production is of great importance. In order to selection of suitable planting date for access of good growth and yield of various sunflower cultivars، special in dryland region، a field experiment was carried out in 2009. Treatments arranged as a split plot in randomized complete block design with three replications in Dryland Research Station of Agricultural Research Center of Kurdistan. Main plots consist of four levels planting date with ten-day intervals from (March 30 - April 30) and sub plots consist of three cultivars: Record، Zarya and Azargol. Results of evaluation total dry matter (TDM) showed that Record cultivar (92 g/m2) had more range of total dry matter. In various planting dates observed that sunflower plants had slow growth in primary stage afterwards had a quick growth، so in second planting date sunflower plants had a quick growth with received 1220 growth degree days. Among various cultivars (varieties)، Record had more crop growth rates and relative growth rate. Planting date and cultivar had a significant effect on grain yield، to be delayed in planting date grain yield reduce، Record had more grain yield (504 kg/ha) but not statistical significant different with Azargol cultivar. Also، among cultivars observed statistical significant different about the productivity efforts. With delay in planting date oil yield reduced. Maximum oil yield (261 kg/ha) was obtained from Record cultivar.