Abstract
Sunflower (Helianthus annuus L.) is a globally significant oilseed crop, yet its yields may suffer due to water deficiency. A field experiment was conducted through two summer seasons (2021 and 2022) at the agricultural research station, Luxor, Egypt, to study the effects of irrigation regime, cultivar selection, and silica gel application on sunflower growth and yield parameters. The experiment utilized a split-split plot design with three irrigation levels based on field capacity (85 %, 70 %, 55 %), three sunflower cultivars (Sakha-53, Giza-102, and Giza-120), and two Silica gel treatments (0 and 300 kg/ha). Analysis of variance revealed significant effects of irrigation (P < 0.001) on all measured traits except 100-seed weight. Utilizing various cultivars also revealed substantial influence, affecting most traits consistently across the two seasons. Silica gel application positively impacted head diameter, 100-seed weight, oil content, and oil yield (P < 0.05). Furthermore, treatments combining moderate irrigation with silica gel application exhibited the highest water productivity, with values reaching 1.35 kg/m³ in the first season and 1.38 kg/m³ in the second season, indicating the synergistic effects of improved water management and silica gel on crop water use efficiency. Multivariate analysis of principal component analysis and clustering heatmap revealed that treatment combinations such as I2S1 (moderate irrigation with silica gel) optimized sunflower productivity, particularly for seed yield and oil content, reinforcing the importance of tailored agronomic practices for maximizing crop performance under varying environmental conditions. These findings underscore the significance of integrated agronomic approaches in enhancing sunflower productivity while promoting sustainable crop management practices.