Effects of mutant cytoplasmic factors on the expression of agronomic traits in cowpea, Vigna unguiculata (L.) Walp.

Abstract

Nuclear genes have to a large extent been exploited in genetic cowpea improvement, but little is known about the effects of cytoplasmic mutations on agronomic traits. This study investigated the effect of cytoplasmic factors agronomic traits in crosses between two cytoplasmic mutants and some nuclear cowpea lines. The experiment was conducted at Department of Crop Protection Environmental Biology, University of Ibadan. A yellow variant derived from the sorting-out of mutant plastids of mixed cells lineage (IB-Y-Cyt.) was crossed to four normal green lines and a variegated mutant in all possible combinations. F₁ and reciprocal-F₁ progenies from the crosses and six generations comprising parents, F₁, F₂ and their reciprocals from four selected crosses were evaluated in pots using Randomized Complete Block Design with four replicates. Data were collected on the following quantitative traits; days to flowering and ripe pod, pod length and seed traits. Data were analyzed using t-test and correlation coefficient analysis. Crosses involving the cytoplasmic mutants as female parents had negative effects on most of the traits studied. The mutant cytoplasms had negative effects on traits affecting the productive capacity of the plants as well as related traits in the F₁ generation, these effects in turn transcend to most of the quantitative traits leading to poor seed formation especially in the yellow cytoplasmic mutant.

Keywords: Cytoplasmic mutation, Agronomic traits, Cowpea, Uniparental, Reciprocal differences