A study was carried out to determine the response of open pollinated sunflower (Helianthus annuus L. cv. Shumos) to boron fertilizer. Spring and autumn grown plots were sprayed with boron (0, 50, 100, 150, 200, and 250？mg？L？1) in a randomized complete block design. The results showed that boron and green Leaf area/LAI measured at the end of seed filling were linearly related in the spring crop. In the autumn crop, the relationship between boron and dry matter yield was linear, and applications above 100？mg？L？1 significantly increased dry matter compared to the control. For the autumn crop, 100, 200, and 250？mg？L？1 significantly increased seed number compared to the control, but only the 150？mg？L？1 treatment increased seed weight significantly. Boron tended to decrease the empty seed percentage, and for the spring crop, this was incremental and linear with applications above 150？mg？L？1 leading to significant reductions in empty seed percentage. Seed yield increased linearly in the autumn crop in response to boron, and 200 and 250？mg？L？1 applications gave significant increases in yield compared to the control. 1. Introduction Sunflower is the third most important oilseed crop in the Middle East after soybean and palm oil and has diverse markets for both oilseed and nonoilseed use including both as a bird food and as a human snack food [1]. Commercial sunflower production in Iraq is currently less than expected because of a variety of reasons including, suboptimal agricultural practices especially in regard to soil management and damage caused by bird attack either at sowing, germination, or flowering stages. Two sowing seasons are commonly used in Iraq, spring (for summer harvest) and summer (for autumn harvest) with a slightly higher yield potential associated with spring sowing due to more suitable growing temperatures. High temperatures at flowering and seed formation stages leads to pollen death and decreased seed fertility, and empty seed can form a high percentage at maturity exceeding 50% in some cultivars [2, 3]. Sunflower pollination is best performed by insects and in commercial fields honeybees are reported to be the most suitable pollinating vectors [2, 3]. Even under optimal honeybee activity in nonoilseed sunflower crops relatively large proportions (15–50%) of seeds can remain empty. The same problem has also been found in oilseed sunflowers but on a smaller scale [4]. Empty seeds are primarily located in the proximal (central) and distal (peripheral) regions of the capitulum [4]. It has been suggested that the empty seeds result from
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