Data/hora: 23/06/2024 04:58:13

Biblioteca(s): | Embrapa Gado de Corte.
Data corrente: | 01/02/2010
Data da última atualização: | 01/02/2010
Autoria: | RICCI, G. C. L.; PAGLIARINI, M. S.; VALLE, C. B. do.
Afiliação: | GLÉIA CRISTINA LAVERDE RICCI, UEM; MARIA SUELY PAGLIARINI, UEM; CACILDA BORGES DO VALLE, CNPGC.
Título: | Chromosome counting and meiotic analysis to select the best accessions in B. decumbens (Poaceae) for hybridization.
Ano de publicação: | 2009
Fonte/Imprenta: | In:SIMPÓSIO INTERNACIONAL SOBRE MELHORAMENTO DE FORRAGEIRAS, 2., 2009, Campo Grande, MS. [Anais]... Campo Grande, MS: Embrapa Gado de Corte, 2009. II SIMF. Comitê editorial: Liana Jank; Lucimara Chiari; Rosângela Maria Simeão Resende.
Páginas: | 4 p.
Descrição Física: | 1 CD-ROM.
Idioma: | Inglês
Notas: | Resumo C 04.
Conteúdo: | Tropical grasses for pastures represent the single most valuable resource in animal production worldwide. Native and cultivated pastures cover wide extensions of land in the tropics, however, are dangerously  composed of a few varieties derived of apomictic ecotypes, creating monocrops (VALLE; PAGLIARINI, 2009). This lack of biodiversity exposes the ecosystems by exerting tremendous selection pressure on pests and/or diseases and justifies the urgency in developing and releasing new cultivars by breeding and/or selection. A number of cultivars have been released in the last 30 years. In Brazil, there are ten registered cultivars listed on the National Service for Cultivar Portection. Brachiaria decumbens cv. Basilisk is the most widely used worldwide because it adapts to acid soils, is easy to manage and readly establishes from seed, presents several agronomic attributes that justify a breeding program on some selected accessions. Brachiaria decumbens has a narrow distribution in Africa. Some countries, as Rwanda, Burundi, and western Kenya are well covered by germplasm roldings. The Brachiaria collection expedition performed during 1984-85 by International Center for Tropical Agriculture (CIAT, Colombia), supported by the International Board for Plant Genetic Resources (IBPGR) resulted in the collection of about 800 accessions of at least 23 known species (KELLER-GREIN et al., 1996). Less than 15% of the collected accessions were of B. decumbens, reflecting their narrow natural distribution. The majority of the accessions are polyploidy, and polyploidy is correlated with apomixis. Although apomictic, the accessions are pseudogamic, which means that viable gametes are necessary to fertilize the secondary nuclei of the embryo-sac (VALLE; SAVIDAN, 1996), (VALLE; PAGLIARINI, 2009). But polyploidy is also correlated with abnormal chromosome segregation during meiosis, affecting pollen viability (MENDES-BONATO et al., 2002), (PAGLIARINI et al., 2008). Thus, the best accessions for breeding will be those presenting high meiotic stability. In this context, the objective it was determine the chromosome number and evaluate the meiotic behavior of 50 accessions of B. decumbens available at Embrapa Beef Cattle (Brazil) as a subsidy to the pre-breeding program.
Palavras-Chave: | Braquiária.
Thesagro: | Brachiaria Decumbens; Gramínea Forrageira; Melhoramento Genético Vegetal; Pastagem.
Categoria do assunto: | K Ciência Florestal e Produtos de Origem Vegetal
Registro original: | Embrapa Gado de Corte (CNPGC)
Exemplares: | CNPGC - (12923-1) - UMT - PL - CD - CD-105 - SIM -  - DIS