Evaluation of cowpea [Vigna unguiculata (L.) Walpers] lines developed through backcross breeding method for early maturity and high grain yield

Abstract

Cowpea [Vigna unguiculata (L.) Walpers] is a herbaceous annual crop predominantly grown in the dry agro-ecologies of the tropics in Latin America, Africa and South Asia. It is an essential crop in Botswana, valued for its nutritional importance and adaptability to the country’s semi-arid climate. The purpose of this study was to evaluate the genetic variability of the cowpea lines developed through backcross breeding method for early maturity and high grain yield. The offsprings were developed between August 2022 and April 2024 using B138 and  ER7 as  parental lines. Four  F1, 9 reciprocal F1, 4 BC1, 6 reciprocal BC1, 8 BC2 and 13 reciprocal BC2 were produced and evaluated for various traits. Days to flowering ranged from 31 (EB-5F1) to 37.00 days (EB9-9-3BC2) while days to 50% flowering ranged from 34 days (EB-5F1) to 40 days (BE3-2-1BC2). The results of this study indicated that EB-5F1, EB8-7-1BC2 and EB8-7-2BC2 can be exploited in breeding programmes targeting earliness and adaptation to short growing seasons. Seed yield per plant ranged from 16.10 g (EB-3F1) to 134.62 g (EB4-1BC1), with BE2-1-2BC2 and EB5-6-1BC2 yielding higher than ER7 but lower than B138. These lines are promising recombinants for further selection and improvement.