Improving the Drought Tolerance in Spring Planted Sunflower by Potassium Application and Sucking Pests Infestation

Water scarcity and improper nutrient management are major constraints to sunflower productivity in semi-arid regions. A two-year field experiment (2023 and 2024) was conducted to evaluate the effects of water stress at critical growth stages and potassium application on growth, yield, quality, nutrient uptake, fatty acid composition, and economic returns of sunflower. The experiment was laid out in a factorial arrangement with different irrigation regimes based on water balance scheduling and four potassium levels (0, 50, 100, and 150 kg K ha⁻¹). Results showed that water stress, particularly at the pre-anthesis stage, significantly reduced plant height, head diameter, achene number, leaf area index, crop growth rate, yield components, achene yield, biological yield, oil content, protein content, and nutrient uptake. Normal irrigation consistently produced the highest growth and yield parameters. Potassium application significantly improved head diameter, achene number, crop growth rate, nutrient uptake (N, P, and K), oil content, protein content, and economic returns. The combined application of normal irrigation and 150 kg K ha⁻¹ (I₀K₃) resulted in the maximum 1000-achene weight, achene yield, biological yield, oil content, and protein content during both years. Water stress increased linoleic acid content but reduced oleic acid concentration, while higher potassium levels slightly improved fatty acid composition. Economic analysis revealed that although 150 kg K ha⁻¹ produced the highest gross income, potassium application at 100 kg ha⁻¹ resulted in the maximum net income and benefit cost ratio. Overall, the study highlights the importance of water balance based irrigation and optimal potassium nutrition in mitigating water stress effects and improving sunflower productivity, seed quality, and profitability under water-limited environments.