Banca de DEFESA: BEATRIZ TOMÉ GOUVEIA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: BEATRIZ TOMÉ GOUVEIA
DATA: 19/12/2019
HORA: 14:00
LOCAL: Departamento de biologia - Anfiteatro DBI02
TÍTULO:

PALAVRAS-CHAVES:

Brachiaria spp. Indirect gain. Biplot. Parental selection. Diallel.

PÁGINAS: 66
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
RESUMO:

Urochloa breeding is complex because involves apomictic and sexual genotypes, selection for multiple traits and the final aim is animal performance. Therefore, the aims of this study were (1) to identify traits with greater direct and indirect effects on yield of high nutritive value leaf mass (NLM) in Urochloa hybrids (2) to assess genetic gains for agronomical and nutritional traits by selection based on selection indexes, NLM, and by genotype by yield*trait (GYT) biplot analysis using NLM as a basic variable, and (3) to estimate the general combining ability (GCA), specific combining ability (SCA) and contribution of additive and nonadditive effects, from a partial diallel cross design between apomictic and sexual parents, for agronomical and nutritional traits in Urochloa spp. For selection strategies, we evaluated 99 interspecific hybrids (U. ruziziensis x U. brizantha x U. decumbens) in an experiment laid out in a randomized complete block design with four replications. For combining ability, a total of 1380 interspecific hybrids from 29 full-sib progenies were evaluated in an experiment laid out in an incomplete block design. In both trials, a series of agronomic traits and nutritive value traits were measured, and the data were analyzed using a mixed model approach. Path analysis and GYT were performed with the basic variable NLM, and different strategies using selection indexes were adopted. The leaf dry matter (LDM) and field green weight (FGW) traits exhibited greater direct effects on NLM. All selection strategies proved to be effective in obtaining gains in the NLM variable. GYT analysis and the selection index with weights corresponding to the relative direct effects to each trait on the NLM were the strategies that resulted in a greater correlated response for NLM. Indirect selection for NLM via FGW or the index with the FGW and regrowth capacity traits proved to be viable strategies for selection of Urochloa genotypes in the initial stages of the breeding cycles due to their practicality and lower requirement regarding traits to be measured. There was a predominance of nonadditive effects on the phenotypic expression of agronomical and nutritional traits in Urochloa spp.

MEMBROS DA BANCA:
Presidente - JOSE AIRTON RODRIGUES NUNES (Membro)
Interno - EVANDRO NOVAES (Suplente)
Externo ao Programa - CAROLINA RIBEIRO DINIZ BOAVENTURA NOVAES - DBI (Membro)
Externo ao Programa - JULIO SILVIO DE SOUSA BUENO FILHO - DEX (Membro)
Externo à Instituição - SANZIO CARVALHO LIMA BARRIOS - EMBRAPA (Membro)
Externo à Instituição - MATEUS FIGUEIREDO SANTOS - EMBRAPA (Membro)
Externo à Instituição - ESTEBAN FERNANDO RIOS - UF (Suplente)