Combining ability among apomictic and sexual parents of Urochloa humidicola

Abstract

The diallel cross constitutes an informative genetic design for choosing genitors and crosses in breeding programmes since it provides estimates of general (GCA) and specific (SCA) combining abilities. Because the breeding programme for Urochloa humidicola ([Rendle] Morrone & Zuloaga; syn. Brachiaria humidicola [Rendle] Schweick) at Embrapa Beef Cattle is recent, these estimates are still unknown. Thus, the aim of this study was to obtain the estimates of GCA and SCA from the partial diallel cross design between sexual and apomictic parents. The crosses involved nine sexual and ten apomictic parents. Seventy‐one full‐sib progenies were obtained and evaluated in an incomplete block design, using all parents and the cv. BRS Tupi as a check. The agronomic and forage quality traits were evaluated using seven harvests. Statistical analysis was performed using the mixed model approach. Significant variations were associated with GCA among sexual parents for biomass yield and forage quality traits. However, this cannot be observed for apomictic parents for GCA. The SCA effect was not significant for the assessed traits. These results showed the predominance of additive effects. Sexual parents SEX3 and SEX4 presented the highest potential for contributing favourable alleles in hybrid combinations. The absence of GCA among apomictic parents and SCA suggests the need to increase genetic variability for the generation of breeding populations of U. humidicola.

Evaluating General Combining Ability for Multiple Traits in Tetraploid Bahiagrass

“…This analysis has been successfully used in major crops, such as maize, to select superior parents based on the performance of their progeny and continue with the breeding process (Bernardo 1999). In single crosses of Urochloa humidicola, an apomictic forage species, this analysis allowed identifying the most promising sexual and apomictic parents based on their general combining ability for forage yield and quality (Figueiredo et al 2019). In this study which consisted of a progeny test belonging to a recurrent selection scheme of tetraploid bahiagrass, the mixed model analysis showed significant differences among families for most of the evaluated traits allowing identification of the best families for each trait (Fig 2).…”

Predictive approach to optimize the number of visual graders for indirect selection of high-yielding Urochloa ruziziensis genotypes

“…Nevertheless, in both cases (selecting versus discarding), it is important to consider that perennial grass breeding programs have a peculiar regrowth evaluation (Berchembrock et al 2020), which limits the number of generations and selection cycles on a per year basis. Various forage breeding programs have used visual evaluation to assess traits at different stages of selection cycles for crops such as red clover (Riday 2009), U. ruziziensis (Souza Sobrinho et al 2010, Teixeira et al 2020, U. decumbens (Matias et al 2020), U. humidicola (Figueiredo et al 2019), and Urochloa spp. (Gouveia et al 2020).…”

Comparison of selection methods among and within full‐sibling progenies in Urochloa humidicola

“…Seventy‐one U. humidicola full‐sib progenies with variable number of hybrids (1 to 46) were obtained, totalling 611 hybrids, from the partial diallel cross between 10 apomictic parents (H1, H120, H146, H193, H3, H30, H319, H347, H54 and H88) and nine sexual parents (H138, H179, H185, H2, H216, H24, H289, H350 and H64) selected by Figueiredo and Barrios (). These unreplicated hybrids, together with the controls (19 parents and cv.…”