Association of traits promoting resistance to the adzuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) in pea genotypes grown at various soil fertility levels

Abstract

Adzuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Bruchidae), is one of the most important pests of pea (Pisum sativum L.) crops in Ethiopia. The study focused on the association of resistance potential in the no-choice test of pea genotypes managed at different fertility levels and trait contributions. Based on the significance of fertility levels, genotypes were grouped into four, six, and five clusters, viz. Under neither rhizobium and phosphorus, rhizobium alone and rhizobium and phosphorus, respectively. Regardless of fertility levels, the inter-cluster distance (D2) values of the two potential clusters were highly significant (P < 0.01). At all fertility levels, the average performance of genotypes in each cluster for individual traits to infestation varied significantly. Genotype distribution patterns tended to group together into a small number of clusters. Eighty genotypes of the pea (Pisum sativum L. subsp. sativum and Pisum sativum L. subsp. abyssinicum A. Braun) were systematically managed under three fertility levels, and the first four principal components accounted for 94%, 92.3%, and 94.2% of the total variation. The primary trait that determines the resistance potential of pea genotypes is the trait susceptibility index (SI), which exhibits highly significant and adverse associations with critical traits such as the date of adult emergency and the percentage of seed coat, while exhibiting highly significant and favorable associations with the remaining traits at all fertility levels. The remaining characteristics showed highly significant positive or negative correlations within and particularly with the characteristics that determine resistance. Therefore, the cultivar "Adi" from "Pisum sativum L. subsp. sativum" had higher susceptibility compared to other genotypes, while the small-seeded pea genotypes "Pisum sativum L. subsp. abyssinicum A. Braun"; fpcoll-1/07, fpcoll-2/07, fpcoll-21/07, and fpcoll-43/07 were moderately resistant.