The effect of nitrogen fixation on the protein quality of southernpeas, Vigna unguiculata (Cowpeas)

Abstract

The effects of nitrogen fixation on protein quality of southernpeas were studied. Differences in levels of nitrogen fixation were induced through variety selection and inoculation with Rhizobium bacteria. Growing seasons also interacted with variety and inoculation effects to produce diverse levels of nitrogen fixation, as determined by measuring nitrogenase enzyme activity, weighing the plant roots and tops, and weighing and counting root nodules. Significant differences in levels of nitrogen fixation were achieved through a combination of cultivar selection, inoculation and other environmental conditions. The high nitrogen fixing Brown Crowder cultivar had a higher protein content; while the low fixing cultivar Mississippi Silver had a lower protein content. The high fixing Brown Crowder cultivar also had higher levels of the sulfur amino acids due to higher levels of protein, but this increased nutritional quality was offset by lower yields. Sensory panelists preferred the flavor and texture of the medium fixing Calico Crowder pea, due to organoleptic characteristics. No adverse effected were found on amino acid profile, protein quality or acceptability due to experimentally induced differences in levels of nitrogen fixation in three cultivars of crowder type southernpeas.