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Perennial grass hybrids of Urochloa are evaluated for at least two years during the screening stage trials (SS) and advanced trials (AD) in breeding programs, an expensive and time-consuming process. In this study, we aimed to evaluate the potential for early selection of cultivars in this breeding scheme. We used multiple measurements of agronomic and nutritive value traits of Urochloa humidicola and Urochloa decumbens in the SS, and Urochloa ssp. in the AD. Repeatability coefficient, genetic correlation, selection efficiency (SE), and Spearman correlations were estimated. The results indicated that reliable early selection could be applied, decreasing the evaluation period to one year and a half for SS, and to one year for AD. These results were confirmed by high genetic and rank correlations, and overall SE above 50%. This proposed change in the breeding scheme could save considerable time, labor, and resources and accelerate the release of improved cultivars. Made available in DSpace on 2019-12-27T18:15:40Z (GMT). No. of bitstreams: 1 Evaluatingearlyselectioninperennialtropicalforages.pdf: 440642 bytes, checksum: bee96446e56a21634ae598716a81207a (MD5) Previous issue date: 2019

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. Made available in DSpace on 2019-12-28T00:36:34Z (GMT). No. of bitstreams: 1 Combiningabilityamongapomicticandsexual.pdf: 757816 bytes, checksum: 7c3419460589d2804b5d4210eed2d3c7 (MD5) Previous issue date: 2019

The objective of this study was to describe the genetic parameters, adaptability, and stability of clones from the Coffea canephora variety ?Vitória Incaper 8142?, and the genetic divergence between them. Following 12 and 24 months of plant growth, several traits were evaluated, including stem diameter, plant height, canopy diameter, number of plagiotropic branches, and number of nodes per plagiotropic branch. The agronomic performance of four crops was determined using measurements of productivity, yield, percentage of floating grains, and grade of the beans. Variability was observed between the clones for the majority of the traits measured. The clones V7, V10, V12, and V13 were the most stable and displayed the highest degree of adaptation for the studied traits, and thus these clones will be used to establish a base population suited to the growing conditions in Alto Suaçuí, Minas Gerais, Brazil. Additionally, the genetic dissimilarity identified between clones allowed suitable clone combinations to be proposed for use in future crosses. Made available in DSpace on 2017-12-07T23:22:54Z (GMT). No. of bitstreams: 1 Adaptabilitystabilityadgeneticdivergence.pdf: 394407 bytes, checksum: d16def10454a3e2bba8fa7e4406a818d (MD5) Previous issue date: 2017-12-07

Este trabalho foi realizado com o objetivo de estimar parâmetros genéticos para caracteres agronômicos e de valor nutritivo da folha e do colmo da forragem de progênies de B. humidicola avaliadas em nove cortes. Além disso pretendeu-se comparar a seleção das melhores progênies de B. humidicola considerando-se apenas os caracteres agronômicos e, posteriormente, em conjunto com os principais caracteres de valor nutritivo. Dissertação (Mestrado em Genética e Melhoramento de Plantas) - Universidade Federal de Lavras. Orientador: Dr.José Airton Rodrigues Nunes. Coorientadora: Dra. Cacilda Borges do Valle, CNPGC.