One year field study was conducted to determine the effect of different levels of nitrogen on growth, development, yield and yield components of sunflower hybrids under. A field experiment was planted to check the effect of different nitrogen rates (0, 45, 90, 135 and 180 kg/ha) on growth and yield components of sunflower hybrids (Hysun 33 and S-78). An experiment was conducted at Research Area of Agronomy Farm, University College of Agriculture, University of Sargodha, Punjab, Pakistan in spring season 2013. The experiment was design RCBD under split plots with three replications hybrids which were allocated in main plots and nitrogen levels in sub plots, respectively. The net plot size was 4.2 × 6 m. The growth parameters, net assimilation rate g m-2 d-1, crop growth rate, and yield parameters were observed as plant height (cm), 1000-achene weight (g) and harvest index (%). The results showed that the highest harvest index S-78 and the lowest showed that Hysun-33.

Keywords: sunflower, nitrogen, growth and yield