Field experiments in vertisols of low, medium and high available soil phosphorus status were conducted to study the response of graded levels of P application to sunflower hybrid (KBSH-1). Effect of P to sunflower in increasing yield and yield attributes was more pronounced in low P status soil. Response equations for seed yield of sunflower at an applied P level have been worked out. Nutrient use efficiency and productive efficiency were also computed. Soil available P status was found to vary significantly only in low P status. Critical P level in soil was found to be 20 kg P ha-1, below which sunflower may respond to phosphorus application.