Potassium(K)and phosphorus(P)applications improve growth,increase yield and yield components of sunflower(Helianthus annuus L.)on K and P deficient soils in Northwest Pakistan.A field experiment was conducted using sunflower cv.Hysun-33 at the New Developmental Research Farm of KPK Agricultural University,Peshawar,Pakistan,during summer 2006.The experimental design was a randomized complete block in split plot arrangements,with six levels of K(0,25,50,75,100,and 125 kg K ha-1)as main plots and four levels of P(0,45,90,and 135 kg P ha-1)as sub-plots with three replications.Sunflower yield and yield components responded positively to K and P fertilization but the magnitude of response varied with the levels of K and P.Days to flowering and maturity,grains per head,1000-grain weight,shelling percentage,and grain yield increased tremendously in the K and P-fertilized plots as compared to the control with no K and P applied.The combined application of 100 kg K and 45 kg P ha-1 significantly increased yield components,grain yield,harvest index,and shelling percentage of sunflower,suggesting that 100 kg K ha-1 in combination with 45 kg P ha-1 could maximize productivity of sunflower planted after wheat on the K and P deficient soils in the study area.