Abstract:
Two years field study was carried out with the objective to determine the effect of different levels of nitrogen (N) on growth, development, yield and yield components of sunflower (Helianthus annuus L.) hybrids under agro-climatic conditions of Faisalabad-Pakistan in spring 2008 and 2009. The experiments were laid out in andomized complete block design with split plot arrangement keeping hybrids in the main plots and N levels in the subplots with three replications. The net plot size was 4.2 m x 5.0 m. The results indicated that with increasing N rates, there was also increment in the total dry matter (TDM), grain yield and yield components while the oil content was negatively affected. There was higher grain yield during 2008 as compared to 2009, probably due to more rainfall in the formation of TDM than in the latter stages. Hysun-38 hybrid gave maximum TDM (13.51 t ha-1) and maximum grain yield (3.08 t ha-1). Minimum TDM (11.94 t ha-1) as well as grain yield (2.92 t ha-1) was observed from Hysun-33. Among different N rates, 180 kg ha-1 gave maximum TDM at 14.02 t ha-1 and achene yield at 3.57 t ha-1 than other N rates. Maximum oil content (41.9%) was resulted from Hysun-38 without application of N fertilizer and minimum oil content (38.4%) was observed from N5 treatment where 240 kg N ha-1 was applied. It was concluded that Hysun-38 with 180 kg N ha-1 proved to be better for good yield of sunflower crop under the prevailing semiarid conditions.
