Estimation of genetic parameters associated with frosty pod rot (Moniliophthora roreri) and cacao production in Mexico

Abstract

Genetic parameters were estimated for frosty pod rot resistance and yield components in cacao using a linear mixed model approach (restricted maximum likelihood and best linear unbiased prediction). Two progeny trials established in the Rosario Izapa Experimental Field of the INIFAP in Chiapas, Mexico, were evaluated for frosty pod rot incidence and yield components, including the number of pods per tree, bean dry weight per tree, number of beans per pod, bean dry weight per pod, seed index, and pod index, for 4 years. Genetic correlations, age-age correlations, and heritabilities were estimated. The narrow-sense heritability for frosty pod rot resistance was 0.46, and for the yield components, it ranged from 0.14 to 0.99. Backward selection, using UF-273 and Pa-169 as parents for new combinations, resulted in a reduction from −36.54 to −29.05% in frosty pod rot, respectively. The genetic correlations between bean dry weight per tree and frosty pod rot, number of pods per tree, number of beans per pod and pod index were −0.72, 0.89, 0.25, and 0.40, respectively (all significant at p < 0.01). Age-age correlations and heritabilities from data subsets indicated that the first 2 years of evaluation and evaluating for only two specific months (August to September) in the year should result almost in the same genetic estimates as using all 4 years data, for key traits, including frosty pod rot resistance, reducing the costs, and accelerating breeding decisions.