Path analysis reveals key traits associated with ascorbic acid in acerola

Understanding relationships among fruit quality traits can support indirect selection for nutritionally important attributes in acerola breeding. This study assessed direct and indirect relationships between fruit quality traits and ascorbic acid (AA) content in 35 acerola (Malpighia emarginata DC.) genotypes evaluated at the big green and red-ripe stages over two production cycles. The experiment followed a randomized complete block design with three blocks per cycle. Genotypic values were predicted by REML/BLUP, and path analyses were performed separately for each maturity stage, considering AA as the response variable and fruit mass, soluble solids (SS), titratable acidity (TA), and firmness as explanatory variables. Multicollinearity was negligible, with variance inflation factors below 1.21. At the big green stage, TA showed the strongest correlation with AA (0.586) and a similar positive direct effect (0.531), indicating a predominantly direct association. Firmness and SS had smaller positive direct effects (0.299 and 0.156), whereas mass had a negative effect (−0.128). At the red-ripe stage, TA showed an even stronger correlation (0.651) and direct effect (0.638), while effects of mass (−0.055), SS (−0.058), and firmness (−0.070) were small. The models explained 43.0 and 43.6% of the variation in predicted AA genotypic values at the big green and red-ripe stages, respectively. Overall, TA was the only trait with a strong, positive, and consistent direct association with AA across maturity stages, indicating its potential as an auxiliary criterion for indirect selection, although direct AA assessment remains important.