Interactive Effect of Potassium and Phosphorus on Grain Quality and Profitability of Sunflower in Northwest Pakistan

A field experiment was conducted using a split plot randomized complete block design with three replications to study the effects of potassium (K) and phosphorus (P) application on sunflower (Helianthus annuus L.) growth at the New Developmental Research Farm of Khyber Pakhtunkhwa Agricultural University in Peshawar, Pakistan. Six levels of K (0, 25, 50, 75, 100 and 125 kg K ha−1) were main plots while four levels of P (0, 45, 90 and 135 kg P ha−1) were subplots. Increase in both K and P levels enhanced grain oil concentration of sunflower. Increase in P level increased grain protein concentration, while increase in K level decreased grain protein concentration. Both oil and protein yields increased significantly with increase in K and P levels. The increase in oil and protein yields of sunflower was mainly attributed to the improvement in yield components (grains per head, grain weight and head size) and the significant increase in grain yield. The highest net returns of 297 and 368 US$ ha−1 based on grain and oil yields, respectively, were obtained from a combination of 100 kg K ha−1 + 45 kg P ha−1.