Influence of plant densities and sowing conditions on Sunflower cultivars yield under semi-arid conditions

A field experiment was conducted to determine the influence of two plant densities Pd1 (50400) and Pd2 (62500) plant ha-1, two cultivars C1 (Samsun-3) and C2 (Funtua), and six sowing conditions Sc1 (Sowing at 22 Feb.-covered), Sc2 (Sowing at 7 Mar.-covered), Sc3 (Sowing at 30 Mar.-free cover), Sc4 (Sowing at 22 Feb.-greenhouse), Sc5 (Sowing at 7 Mar.-greenhouse) and Sc1 (Sowing at 30 Mar.-free cover plus two irrigations) on yield contributing traits of sunflower under rainfed condition. Results showed that the effects of plant densities, cultivars, sowing conditions, and their interaction on the studied yield parameters, disk weight, disc diameter (cm), 1000- seed weight (g), number of seed disc-1 and seed yield (t h-1) were highly significant (P≤0.01). Maximum mean values were recorded for the disk weight (g) and number of seed disc-1 in Sc3 (Mar-30) with Samsun-3 and Pd1(50400 plants ha-1), disc diameter in Sc4 (Feb-22) with Samsun-3 and Pd1(50400 plants ha-1), 1000- seed weight (g) in Sc4 (Feb-22) with Samsun-3 and Pd1(50400 plants ha-1), and seed yield (t h-1) in Sc4 and Sc2 (Feb-22) with Samsun-3 and Pd1 (50400 plants ha-1). According to the seed yield, Samsun-3 surpassed Funtua by 23%, while Pd2 surpassed Pd2 by 17%. Yield reduction was large under Sc3 late spring sowing (22 %) compared with too early sowing Sc4. Based on the results, it is concluded that high quantity production was obtained on the Feb-22 date of sowing with Samsun-3 under a high population (62500 plants ha-1). Favorite or Performer variety can be grown for their high seed under climate conditions in Sulaimany-Kurdistan-Iraq or other similar areas.