13.12.2023

Accuracy of predicted breeding values (PBV) for low heritability traits may be increased in early generations by exploiting the information available in correlated traits. We compared the accuracy of PBV for 10 correlated traits with low to medium narrow-sense heritability (h^2) in a genetically diverse field pea (Pisum sativum L.) population after univariate or multivariate linear mixed model (MLMM) analysis. In the contra-season, we crossed and selfed S1 parent plants, and in the main season we evaluated spaced plants of S0 cross progeny and S2+ (S2 or higher) self progeny of parent plants for the 10 traits. Stem strength traits included stem buckling (SB) (h^2 = 0.05), compressed stem thickness (CST) (h^2 = 0.12), internode length (IL) (h^2 = 0.61) and angle of the main stem above horizontal at first flower (EAngle) (h^2 = 0.46). Significant additive genetic correlations occurred between SB and CST (0.61), IL and EAngle (-0.90) and IL and CST (-0.36). The average accuracy of PBVs in S0 progeny increased from 0.799 (univariate) to 0.841 (MLMM) and in S2+ progeny increased from 0.835 (univariate) to 0.875 (MLMM). An optimized mating design was constructed with optimal contribution selection, and predicted genetic gain in the next cycle ranged from 1.4% (SB), 5.0% (CST), 10.5% (EAngle) and -10.5% (IL), with low achieved parental coancestry of 0.12. Rapid genetic gain is predicted in these correlated traits based on high accuracy of PBV in early generations.