Effects of potassium and boron fertilization on sunflower yield, oil content, and quality

Potassium (K) and B are important for phloem translocation, reproductive growth, and grain formation. A 2-yr field study was conducted to evaluate the effect of K and B applied through the soil and foliar application on sunflower (Helianthus annuus L.) Experiments included the soil application of K (62 kg ha(-1)) and B (5 kg ha(-1)) and foliar spray of K (1%) and B (0.1%). Furthermore, the soil-applied K and B was supplemented with three foliar sprays of either K, B, or both at 45, 60 and 75 d after sowing. The results revealed that K and B fertilization improved the agronomic parameters of sunflower, including plant height, head diameter, achenes per head, achene weight, yield, seed oil contents and oil quality. The soil applied K at 62 kg ha(-1) followed by foliar spray of 1% K + 0.1% B at 45, 60 and 75 DAS resulted in production of taller plants (192 and 172 cm), head diameter (23 and 28 cm), achene per head (954 and 1063), 1000 achene weight (68 and 67.58 g), achene yield (2976 and 2621 kg ha(-1)), biological yield (11363 and 8430 kg ha(-1)), oil contents (43.37% and 41.87%), and oleic acid (70.33% and 80.83%) over 2 yr of study. Hence it can be concluded that soil application of 62 kg ha(-1) K followed by foliar application of 1% K + 0.1% B is the preferable fertilization strategy for sunflower for improved yield, seed oil contents, and oil quality.