Effects of Bradyrhizobium japonicum Inoculation and Supplementation with Phosphorus on Macronutrients Uptake in Cowpea ( Vigna unguiculata (L.) Walp)

Abstract

The current study was conducted to assess the effects of phosphorus supplementation and Bradyrhizobium ja-ponicum inoculation on the availability and uptake of N, P, K, Mg, Ca and Na on cowpea. The experiment was laid out in a split plot design where the main plots comprised two inoculation levels (with and without inocula-tion of B. japonicum) and sub plots contained four different levels of phosphorus (0, 20, 40, and 80 kg P/ha). The results indicated that B. japonicum inoculation and phosphorus supplementation significantly improved the up-take of N, P, K, Mg, Ca and Na in different cowpea tissues such as roots, pods, shoots, and whole plant relative to the control. The results also indicated that there was a significant interaction of B. japonicum and phosphorus on the uptake of sodium in the roots and whole cowpea plant in the screen house. Rhizobia inoculation and supple-mentation of phosphorus at 40 kg P/ha resulted in the improved uptake of the most elements over other treat-ments tested.