Physiological growth and yield evaluation in P-mineralized sunflower (Helianthus annuus L.) under sundano-sahelian agro-ecology, Nigeria

The study was carried out at the Research and Demonstration Farm, Department of Crop Production, University of Maiduguri (11 degree 47 'N, 13 degree 13 'E) during 2010 and 2011 rainy seasons, to investigate the response of sunflower to phosphorus fertilizer inorganically applied as P2O5 @ 0, 20, 40, 60 and 80 kg per ha. The experimental design was randomized complete block and replicated thrice. It was observed that leaf area per plant and plant dry weight increased with increasing P2O5 rates (40-60 kg per ha) at 6, 8 and 10 weeks after sowing (WAS). Crop growth rates similarly increased with increasing P2O5 rates (40-80 kg per ha) at 6 WAS in both years and the combined means for the two years, and at 8 WAS in 2011 and the combined analysis. Days to 50% flowering and head dry weight were not significantly influenced by P2O5 rates and 1000-grain weights indicated that increased P2O5 application (40-80 kg per ha) P2O5 enhanced grain filling efficiency and this influenced weight per 1000-grains during both years. The application of 40 kg P2O5 per ha increased grain yield statistically in 2010 rainy season (2289.10 kg per ha) and the combined analysis (1565.20 kg per ha). During 2011 rainy season, 80 kg P2O5 per ha recorded statistically higher grain yield (1153.60 kg per ha). Similarly, the application of 80kg P2O5 per ha statistically influenced higher fodder yield (4112.60 kg per ha) in 2010 rainy season; while 60 kg P2O5 kg per ha yielded statistically higher fodder values during 2011 (1873.00 kg per ha) and combined analysis (2393.30 kg per ha). Application of 60 kg P2O5 per ha also increased the biological yield statistically in 2010 (3709.70 kg per ha) and lower P2O5 rate of 40 kg per ha statistically yielded 3980.80 kg per ha in the combined analysis while biological yield was not statistically significant during 2011 rainy season. Considering 40 kg P2O5 per ha in yield performances for grain and fodder in this experiment, it could be recommended for farmers' adaptive farm trials in the agro-ecological location.