Genetic Variability of Quantitative Traits in F2 Hybrids of Cowpea and Parent Lines

Abstract

The grain yield of cowpea across the producing countries falls below expectation due to diverse production constraints. Hence, it seems that broadening its genetic base for sustainable yield improvement and tolerance to environmental stresses in the context of global climate change is necessary. Therefore, the objectives of the present study is to evaluate the genetic differences and correlation of characters in F2 hybrids of cowpea and their parent lines. The present study was performed in the field during the rainy season. The obtained data were subjected to various statistical analyses. The hybrids and the parents exhibited significant variation for all the traits studied, including the seed yield. High variability among the offspring and parents suggests better chances of producing the desired recombinants in the successive generation. Emergence ranged between 53.04% in offspring of IT98K-555-1 × IT98K-205-8 and 73.68% in IT98K-555-1. Parents exhibited higher main branches (4.72 and 4.80). IT98K-555-1 was superior for most traits, including the seed yield per plant (288.64 g). However, IT98K-205-8 flowered first at day 45 while IT98K-555-1 flowered last at day 56. Traits such as emergence percentage, days to first flowering, pods/plant, and seed yield/plant exhibiting a combination of high broad-sense and narrow-sense heritability (˃ 60%) and high genetic advance as a percent of the mean (˃ 20%) indicated that they were under genetic control and responsive to the improvement. Traits such as plant height, seeds/pod, pods/plant, and seeds/plant with a high positive genotypic correlation (r ≥ 0.99) to seed yield/plant could be considered the core selection indices in cowpea improvement programs. Nonetheless, further studies into F3 and later generations are required to exploit the relationships between the high yields, seed coat color, and drought tolerance among the cowpea hybrids.

Keywords

• coefficient of variation
• genotypic correlation
• heritability
• reciprocal crosses