Department of Agricultural and Environmental Sciences;
Tennessee State University;
Nashville;
TN;
USA;
Department of Biotechnology;
University for Development Studies;
Tamale;
Ghana;
Council for Scientific and Industrial Research;
Savannah Agricultural Research Institute;
Tamale;
Ghana;
Department of Crop Sciences;
Tshwane University of Technology;
Pretoria;
South Africa;
Drought; Cowpea; Carbon; Isotope; Discrimination; Nitrogen; Fixation; Grain; Yield;