Response of the Yield of Sunflower (Helianthus annuus L.) Cultivar Armavirski to Sowing Time and Plant Density in Rain Fed Conditions in Ghorveh Kordestan

The cultivation of sunflower cultivar Armavirsky which has shown advantages under both rain fed and various irrigation system conditions in different areas, is also common in the Kurdestan province. In order to determine the sowing time and appropriate plant density of this cultivar in the region, the effects of three sowing times on 18th April, 29th April, and 9th May, and 6 density levels 10, 8, 7.1, 6.6, 5.7 and 4.7 plant/m2 respectively. The experiment was carried out as split plots in a randomized block design with three replicas. By analyzing the seed yield, oil percentage, number of seeds per cap, 1000-seed weight and the percentage of unfilled grains, it was found that with a delay in the sowing time the number and weight of seeds per cap, 1000 seed weight and seed yield decreased significantly but the percentage of unfilled grains increased. Although by decrease in plant density the traits related to the weight of grain per cap, 1000 seed weight, unfilled grains percentage and seed yield were increased, the number of grains per cap was decreased. Based on the findings of this experiment and in order to achieve the highest yield, the sowing time of 18th April and the plant density of 4.7 plants per square meter in the Ghorveh region of Kurdistan and other regions with similar ecological conditions are recommended.