Growth and yield response of cowpea (Vigna unguiculata L. Walp.) as affected by phosphorus levels and bradyrhizobial strains in Kano State, Nigeria
Field trials were conducted during the 2015 wet season at the Bayero University Kano Teaching and Research Farm and National Institute of Horticultural Research Technology (NIHORT), Bagauda. The study was conducted to determine the effect of phosphorus levels and Bradyrhizobial strains (USDA 3384 and 3451) on the growth and yield of cowpea varieties in the Sudan savanna zone of Nigeria. The treatments consisted of four (4) cowpea varieties (UAM-09-1051-1, IT99K-573-2-1, IT99K-573-1-1, and TVX 3236), two (2) levels of Bradyrhizobium (0, and 100 g/ha) and three (3) levels of phosphorus fertilizer (SSP) (0, 20, and 40 kg/ha) which were laid out in a Split Plot Design (SPD) and replicated three (3) times. Phosphorus levels and inoculation were allocated to the main plot while variety occupied the sub plot. The result revealed that application of 40 kg/ha P2O5 statistically recorded the highest grain yield ha-1 ()at BUK. No significant phosphorus effect was recorded on grain yield ha-1 at Bagauda. Bradyrhizobium Spp. Inoculation on cowpea had also maintained a consistent result across the two locations with the exception of emergence count which was found to be higher at Bagauda and BUK respectively. Significantly higher grain yield was observed from inoculated plants at BUK (1007.220 kg/ha) and Bagauda (719.91 kg/ha). The findings of the study also revealed that there was significant varietal effect on cowpea growth performance at both study locations. Higher grain yield was recorded from variety IT99k-573-2-1 (1193.400 kg/ha), followed by variety TVX 3236 (950.900 kg/ha) and IT99k-573-1-1 (776.500 kg/ha) at BUK while no significant effect of variety was recorded at Bagauda. Based on the result of the study, application of 40 kg/ha P2O5 can be recommended for better cowpea growth and yield at BUK. Similarly, variety IT99k-573-2-1 can be recommended to BUK location.
Keywords: USDA 3384 and 3451, Cowpea varieties, Phosphorus ad Sudan savannah