Nitrogen Fixation and Yield Potential of Some Early-Maturing Cowpea (Vigna Unguiculata (L) Walp) Lines

Abstract

Field experiment was conducted at Mampong Campus of the University of Education to determine the yield and nitrogen fixation potential of some cowpea lines. Nine lines plus Asontem variety were studied in a Randomized Complete Block Design with four replications. The results showed that all the lines nodulated freely with the natural rhizobia in the soil. There was significant differences (P<0.05) in the nodulation abilities of the lines. Number of nodules negatively correlated with nodule dry weight (r= -0.38) whiles the amount of nitrogen fixed positively correlated with total seed yield (r= 0.94). Line IT97K-506-1 produced the highest number of nodules per plant but did not fix the highest amount of nitrogen. Lines IT97K-566-18 and IT97K-570-18 which contained the highest amount of nitrogen (4.43 and 4.70kgN/ha) respectively in their residue also produced the highest seed yield (3.58 and 3.61t/ha) respectively. The results showed that lines IT97K-570-18 and IT97K-566-18 have high yielding potentials and N-fixing abilities and should be tested on farmers’ fields.

Key words: Cowpea (Vigna unguiculata (L) Walp), Nitrogen Fixition, Anova, Soil Fertility.