Impact of plant densities and NPK fertilization on growth and optimum economic return of sunflower.

A field experiment was conducted to study the response of sunflower hybrid (Hysun-33) to different plant densities (11.11, 5.5 and 3.7 plants m) and NPK levels (50:50:0, 100:100:50 and 150:120:100 kg ha) at the Faculty of Agriculture, Gomal University, Dera Ismail Khan during spring 2011. Growth and yield traits of sunflower such as days to flowering, plant height, disc diameter, 1000-seed weight, number of seeds disc, seed yield, biomass yield and harvest index were significantly (P0.05) affected by planting densities and NPK levels. The highest plant height (162.88 cm), seed yield (4645.8 kg ha) and biomass production (19736 kg ha) was recorded under the highest plant density (11.11 plants m) used in this experiment that received the highest fertilizer dose of 150:120:100 NPK kg ha. On the other hand, the head diameter, 1000 seed weight, and seeds head were the lowest under lowest planting density (3.7 plants m) that received the highest fertilizer dose. It is important to note that the highest benefit-cost ratio (BCR = 3.9) was obtained with highest planting density (11.11 plants m) and highest fertilizer dose (150:120:100 NPK kg ha). Based on this data 11.11 plants m plant density and 150:120:100 kg haNPK fertilizers are recommended to get the highest yield and net return of sunflower under the agro-climatic conditions of Dera Ismail Khan.