Biological nitrogen fixation by 15n isotope techniques in thesenegalese Cowpea: Method of a value

Niébé or cowpea [Vignaunguiculata(L.)Walp.] is a grain legume which occupies an important place in african agriculture. The ripe seeds contain high levels of protein, starch, B vitamins (folic acid), and are also rich in essential trace elements (iron, calcium and zinc). Protein-rich tops are also a preferred feed the livestock. In combination or in rotation with other crops, cowpea may yield 60-70 kg / ha of fixed nitrogen for the next crop (Rachie, 1985). The objective of our study is to estimate the biological fixation of the nitrogen of various varieties of cowpea from the national germplasm and to estimate their genetic variability to target interesting varieties. Isotope techniques used for the assessment of biological nitrogen fixation of 16 cowpea varieties have allowed us to classify the different varieties according to their potential for nitrogen fixation (NdFix) and their ability to take nitrogen from the soil. The results obtained allowed to target cowpea varieties that can be introduced into soil fertility improvement programs and increasing crop yields.