Irrigation in relation to phosphorus nutrition in summer sunflower (Helianthus annuas L.)

An experiment was conducted on sandy loam soil during summer 1996 to study the performance of sun flower(Hy KBSH 1) as influenced by levels of irrigation and phosphorus nutrition. Four irrigation levels (0.6, 0.8, 1.0 and 1.2 IW/CPE) in main plot and three phosphorus levels (25,50 and 75 kg P₂O₅ ha⁻¹) as subplots were laid out in split plot design with four replications. Significantly higher seed yield of 2103 kg ha⁻¹ was recorded with irrigation at 1.2 IW/CPE compared to 1.0 (1689 kg ha⁻¹), 0.8 (1267 kg ha⁻¹) and 0.6 IW/CPE (1080 kg ha⁻¹). Crop fertilized with 50 (1593 kg ha⁻¹) and 75 kg Pps ha⁻¹ (1688 kg ha⁻¹) recorded significantly higher yield over 25 kg ha⁻¹(1324 kg ha⁻¹). At each level of irrigation, the seed yield increased with increase in P application. Maximum seed yield was obtained with 75 kg Pps ha⁻¹ at 1.2 IW/CPE level of irrigation. Field water use efficiency (FWUE) was high with 0.6 IW/CPE (9 kg seed mm⁻¹ water applied) and phosphorus use efficiency (PUE) was maximum with 25 kg P₂O₆ ha⁻¹ (53 kg seed per kg of kg P₂O₅ applied).