Effect of Spatial Distribution and Nano-Boron Foliar Spray on the Yield of Two Sunflower Cultivars under Aswan Conditions

The field study was carried out during the 2023 and 2024 growing seasons at the Experimental Farm, Faculty of Agriculture and Natural Resources, Aswan University, to evaluate the effects of plant spatial distribution, foliar application of nano-boron, and sunflower cultivars on yield and its components. The experiment followed a strip-split plot design within a randomized complete block design (RCBD) with three replications. Results showed that the 25 × 70 cm spatial distribution was the most effective, producing seed yields of 1903 and 2189 kg fed⁻¹, representing increases of 5.8% and 5.0% over the 30 × 60 cm spacing, and 7.8% and 11.5% over the 35 × 50 cm spacing in the two seasons, respectively. Oil yields reached 819 and 940 kg fed⁻¹, exceeding the 30 × 60 cm spacing by 8.5% and 9.0% and the 35 × 50 cm spacing by 12.8% and 13.9%, respectively. Foliar application of nano-boron had significant effects, with the 80-ppm treatment recording the highest seed yields (2067 and 2502 kg fed⁻¹), surpassing the control by 22.7% and 36.7% in the first and second seasons. Oil yield under 80 ppm treatment reached 880 and 1089 kg fed⁻¹, representing increases of 28.0% and 44.8% over the control. Cultivar comparison revealed that Giza 102 outperformed Sakha 53 in all traits except oil percentage. Giza 102 achieved 1886 and 2135 kg fed⁻¹ for seed yield and 780 and 890 kg fed⁻¹ for oil yield across the two seasons, while Sakha 53 recorded higher oil percentages of 42.1% and 42.2%.