Using additive indices and principal components to select sexual genitors and hybrids of Urochloa decumbens

Abstract

The selection of sexual genitors in Urochloa decumbens breeding is dependent upon the performance of their progeny for several traits simultaneously. Thus, our objectives were to (i) compare the efficiency of indices to select genitors of U. decumbens, (ii) evaluate the genetic gains obtained through selection intensities, and (iii) evaluate the multivariate pattern of progenies through principal components analysis (PCA). For this purpose, 1415 hybrids from 75 progenies of full siblings were evaluated at Embrapa Beef Cattle (Brazil) using seven cuts for dry matter production, regrowth, protein, fiber, lignin, and percentage digestibility. Statistical analyses were performed using mixed models and PCA. The direct selection for dry matter production provided a 37.51% genetic gain. Agronomic traits using indices provided greater gains. Genitors selected using PCA Biplot were similar to selections using indices. Indices and PCA were proven to be an excellent tool to select multi-traits in U. decumbens.

Evaluating General Combining Ability for Multiple Traits in Tetraploid Bahiagrass

“…In this work, this selection tool was effective since it allowed us to select the 10 sexual parents that exhibited grater general combining ability based on their progeny behavior. It was also effective to estimate specific combining ability of a group of sexual genotypes of Urochloa decumbes taking into account a group of agronomic and nutritive traits (Matías et al 2020). These results are indicating that selection index based on mean BLUP might be use as a tool to estimate general and specific combining ability in recurrent selection schemes.…”

“…Nonetheless, it allowed selecting six families that highlighted for some of the most important forage traits. This analysis was also effective in a recurrent selection based on specific combining ability scheme of Urochloa decumbens, where it allowed to select the best sexual parents for agronomic and nutritional traits (Matías et al 2020). These data are indicating that in apomictic species the use of multivariate analysis based on BLUP were successful to identify sexual parents with greater general or specific combining ability based on their progeny behavior.…”

“…BLUP for estimating genetic parameters has been extensively used in sexual crops such as Zea mays (Bernardo 1999), however, in apomictic forage species there are few studies. In Urochloa decumbens, Matías et al (2020) were able to estimate specific combining ability of a group of sexual genotypes using indexes based on BLUP predictions.…”

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).…”

Combining ability and selection for agronomic and nutritional traits in Urochloa spp. hybrids

“…In forage breeding, the breeding pipeline is more complex than other crops because the goal is to improve traits of the forage to increase gain in animal performance (Valle et al, 2008), while decreasing methane emissions (Lee et al, 2017). The hybrid selection has been accomplished by additive indexes with subjective weights for several agronomical and nutritional traits or using biplots for major traits (Mateus et al, 2015;Matias et al, 2018Matias et al, , 2020. However, the selection based on NLM might be more effective for selecting superior hybrids in Urochloa (Gouveia et al, 2020).…”