Evaluating general combining ability for agro-morphological traits in tetraploid bahiagrass

Recurrent selection based on combining ability has been successfully used in tetraploid bahiagrass (Paspalum notatum Flüggé) to accumulate heterotic effects and exploit hybrid vigor. However, its efficiency depends on an accurate selection of the best genotypes to form a new recombinant population. The objective of this work was to assess the general combining ability of female parents of bahiagrass based on the performance of their progeny for agronomic and morphological traits using a mixed model approach, biplot analysis and selection index. Twenty-nine half-sib families were evaluated. They were generated by crossing 29 sexual tetraploid genotypes from a sexual synthetic tetraploid population and a group of apomictic tetraploid genotypes. Agronomic and morphological traits were analyzed using a mixed model approach (BLUP). The multi-trait analysis was based on a biplot analysis and a selection index using the family BLUPs. BLUP analysis showed significant differences among families for most of the evaluated traits. Sexual female parents of families 5, 9, 8, 28, 21 and 16 were identified as those with greater general combining ability. Biplot showed variability among families and allowed identifying six sexual parents with greater general combining ability. The same sexual parents that exhibited greater general combining ability by BLUP were identified with greater general combining ability by biplot. Selection index was variable among half-sib families and allowed identifying the same best sexual parents that BLUP and biplot. The three analysis methods were equally effective to estimate general combining ability of a group of sexual parents of tetraploid bahiagrass based on the performance of their progeny.