Análise de trilha e estimativas de parâmetros genéticos para vitamina c e relação sólidos solúveis e acidez em progênies de goiabeira

Abstract

This dissertation investigated genetic improvement strategies for guava (Psidium guajava L.), a crop of economic relevance in Brazil, through the estimation of genetic parameters and the analysis of interactions among physicochemical and agronomic traits in progenies derived from three controlled crosses. Evaluations were conducted over three and four production cycles, according to the dataset analyzed, using analysis of variance, mixed models, and variance component-based methods to estimate heritability and repeatability, as well as phenotypic correlations with decomposition into direct and indirect effects through path analysis. The results revealed a positive association between vitamin C and soluble solids, as well as with the soluble solids/acidity ratio, and a negative association with yield-related and fruit size traits. Path analysis indicated a direct effect of the soluble solids/acidity ratio on vitamin C content, suggesting trade-offs in the simultaneous improvement of these traits. Transgressive segregants for vitamin C were identified, with values exceeding those of the parents, reaching up to 486.1 mg/100 g. Broad-sense heritability estimates were moderate in the PR (0.43) and PSR (0.51) populations and low in PSP (0.13), whereas for the soluble solids/acidity ratio, heritability was moderate only in PSR (0.42). Repeatability coefficients reached up to 0.46 for vitamin C and 0.39 for the soluble solids/acidity ratio. Overall, the results indicate the feasibility of selection for improving fruit nutritional quality, with emphasis on the PSR population.