Growth Assessment, Grain and Fodder Yield Potentials of Sunflower (Helianthus Annuus L.) Under Varying Phosphorus Rates in Southern Borno, Nigeria

Field experiments were conducted during successive rainy seasons of 2010 and 2011 at Wamdeo South of Borno State (100 30ʹ N, 130 09ʹE), 523 m above sea level in Sudan-Northern Guinea savanna transition of Nigeria. This was to study the performances of yield parameters, yield components and some yield contributing growth parameters under various phosphorus rates (0, 20, 40, 60 and 80 Kg P2O5 ha –1). The treatments were laid in randomized complete block design and replicated three times. Results showed that phosphorus application did not influence physiological growth parameters during most of the first sampling periods. Leaf area per plant increased with higher and statistically similar values recorded among 60-80 Kg P2O5 ha–1 during most of the sampling periods. Similarly, the application of 60-80 Kg P2O5 ha–1 recorded higher and statically similar crop growth rates during most of the sampling periods, as results were not statistically significant in 2010 (6 WAS), 2011 (8 and 10 WAS), and two years mean (6 and 10 WAS). Dry matter production also increased with increasing phosphorus application with statistical similarities among 40–80 Kg P2O5 ha–1 during most of the sampling periods, except at 6 WAS during 2011 rainy season. Data on yield components showed that days to 50% flowering reduced statistically with increasing P2O5 rates up to 60 Kg ha–1 in 2011 rainy season and the two years combined means averaging 75.13 days. Similarly, increasing P2O5 rates to 60 Kg ha–1 increased head dry weight in the two years mean (89.62g), and the performance of 1000-grain weight during 2011 rainy season. However, 20-80 Kg P2O5 ha–1 recorded similar values for 1000-grain weight in 2010 and the two years mean. Phosphorus application also influenced yield parameters as 40-80 kg P2O5 ha–1 increased grain yield with yield value for the two years mean averaging 2114.60 Kg ha–1 at 40 Kg P2O5 ha–1, which could be the recommended rate for seed growers in the study area. Similarly, application of 60 Kg P2O5 ha–1 statistically increased fodder yield with average value of 2546.20 Kg ha–1 recorded in the two years mean, which could be the recommended rate for optimum fodder yield benefit among sunflower growers in the study area. Conclusively, therefore, sunflower seeds and haulms can complement Nigeria’s traditional edible oil and the off-season availability of dry fodder for livestock use respectively.