Variabilidad genotípica y ambiental de parámetros morfológicos del grano de cebada cervecera (Hordeum vulgare L.) y su relación con parámetros de calidad maltera

Barley in Uruguay is the second most widely grown winter crop, and its main use is for malting, primarily for export. Malting quality is a key factor in its suitability for brewing. Understanding how malting quality parameters vary and how they are influenced is important for the efficient development of new cultivars. The main objective of this study was to evaluate the relationship between barley grain morphological parameters and fine extract, a malting quality parameter. Morphological parameters were measured in commercial cultivars and advanced lines from the INIA Breeding Program to determine whether barley grain morphological parameters (width, length, A_L ratio, perimeter, area, color) could serve as indicators of malting quality in earlier generations of the breeding program. Finally, the predictive power of these variables was assessed, validating their usefulness using independent phenotypic data from F7 lines obtained in preliminary trials. The Advanced and Elite trials were planted in the INIA Barley Breeding Program in 2023 using a randomized incomplete block design with two replications. The variables evaluated were 1000-seed weight, grain classification, morphometry, and malting quality for each sample. For malting quality analysis, the samples were micro-malted by the Uruguayan Technological Laboratory (LATU). Analysis of variance for the different variables was performed using mixed models, incorporating spatial analysis of the trials. For estimating fine extract, a multiple linear regression model with stepwise variable selection was used. The variance values ​​for yield, in both the Elite and Advanced trials, showed that most of the observed variability was explained by environmental effects. In contrast, the variables 1000-seed weight, grain classification, and morphometric parameters showed that the main source of variation was the genotypic effect. Regarding the correlations between morphometric parameters and malting quality, it was observed that seed size classification and 1000-seed weight showed a positive correlation, and grain width also demonstrated a positive correlation with both variables. The correlation between grain protein content and extract yield was negative in the trials evaluated. Among the regression models, the equations corresponding to the elite and preliminary trials were the most significant. Finally, among the models used to predict extract yield in Preliminary trials, the equation developed from the Elite trials was the most accurate, due to a higher coefficient of determination. This equation included grain protein content, grain width, and grain length as predictor variables. Therefore, determining parameters such as grain width, grain length, and grain protein content in an experimental line would allow for an estimation of malting quality in earlier generations of breeding programs, through a simpler measurement and without the need for pre-selection based on other characteristics.