Response of sunflower (Helianthus annuus L.) to phosphorus and nitrogen fertilization under rainfed conditions, blue nile state-sudan

Abstract

Two field experiments were conducted on a typic chromusterts, fine, smectitic, isohyperthermic soil series in the Damazin Research Station Farm during two seasons (2005/06 and 2006/07). The objective was to investigate the effect of phosphorus (P) and nitrogen (N) and their interactions on sunflower (Helianthus annuus L.) growth, seed and oil yield. A randomized complete block design with four replicates was used to execute the experiments. Plant height, dry matter and seed yield were significantly increased by N and P applications in both seasons. The average yield of sunflower seed in the two seasons was 0.486 tons·ha-1 for the control and 4.893 tons·ha-1 for the highest fertilizer treatment (N80P80). Oil seed % gave significant increases in the two seasons due to P, N treatments and their interaction, and the average oil seed was 31.3% for the control compared to 37.5% for the highest treatment (N80P80). Phosphorus alone had pronounced effect on oil seed % in the two seasons. There were mutually synergistic effects between N and P which significantly (P<0.01) promoted growth and yield of sunflower. Phosphorus enhanced nitrogen uptake and nitrogen use efficiency and vice versa. At all N applications, phosphorus use efficiency tended to decrease with increase in the rate of P application. The highly significant response of sunflower to P and N fertilizers warrant recommending their application under the rainfed conditions of Damazin, Sudan.