Genetic analysis and heterotic potential of onion (Allium cepa L.) for some physiological and agronomic traits under rainy-season cultivation

Abstract

Onion ( Allium cepa L.) is the second most commonly produced and consumed vegetable worldwide. In West Africa, high heat and moisture are key constraints for onion productivity during the rainy-season. This study aimed to assess the combining ability, heterosis, and genetic variability of five onion genotypes and 10 F 1 hybrids generated through a half diallel mating design to identify superior parental lines and hybrids adapted to heat and moisture conditions. The experiment involved five parents: Prema 178, EW001, Violet d’Abéché, Violet de Galmi and AC980. The trials were implemented on station at the World Vegetable Center in Samanko by using a randomized complete block design. Twelve morphological, physiological, and agronomic traits were evaluated. Analysis of variance showed substantial genetic variability. Significant general combining ability (GCA) and specific combining ability (SCA) effects indicated that both additive and non-additive gene actions influence key traits. The best general combiner was Parent P1 (Prema 178), which had the best positive GCA effects on plant survival rate (5 and 4.98), plant height (2.36 and 2.53), number of bulbs (5.82 and 3.38), and bulb yield (2.09 and 2.44). The hybrids P4×P5 (Violet de Galmi x AC980) and P1xP5 (Prema 178×AC980) had the most positive SCA effects and the best heterosis values over the midparent (105.26%) and better parent (94.56%) for bulb yield, as well as strong vigor and root growth. These results demonstrate that the hybrids P4×P5, P1×P5, and P3×P5 are good candidates for multilocation testing in high heat and high moisture prone conditions.