Cruzamento dialélico de genótipos da mini-coleção nuclear de arroz da Embrapa
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2011-08-26
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Universidade Federal de Goiás
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The Embrapa Rice Core Collection (ERICC) was established aiming to represent the genetic variability of the rice Genebank of Embrapa Rice and Beans. The agronomic and molecular characterization of 550 accessions from ERICC enabled to know the extension of the genetic variability of this collection. The molecular data from ERICC genotyping using 86 SSR markers were used to set up a sub-sample, known as Mini-ERICC, which was assembled with the 24 accessions with higher average genetic distance, 12 from upland and 12 from lowland accessions. Since the Mini-ERICC represents a large part of the rice genetic variability from Brazil, the crossings among its accessions could create several new allelic combinations. This dissertation aimed to determine, by means of diallel crosses from Mini-ERICC lowland accessions, plus four additional genotypes from ERICC, the estimates of genitor effect, genitor heterosis, Specific Combining Ability (SCA), General Combining Ability (GCA) and the correlation between heterosis and molecular genetics distance. The 16 genitors and 120 F1 hybrids were evaluated by 10 traits in a field experiment using a 12 x 12 Lattice experimental design. It was possible to identify crosses with high SCA for all traits. These information will be useful in planning new broad genetic basis crosses, aiming new hybrid combinations and the development of populations to extract genetically divergent inbred lines in relation to those currently selected in Brazilian rice breeding programs.The 33 hybrid combinations that did not differ the productivity in relation to high-yielding genitors and controls (P<0,05) indicated that crosses involving at least one less adapted genitor are able to generate favorable allele combinations to breeding programs. The RW genetic distance between genitors from hybrid combinations was positively correlated to traits plant height, panicle length, spikelet number, and negatively correlated to percentage of filled grains and yield. The crossings with rice must prioritize, initially, the maximization of rice genetic variability, and at the end, the development of lines and cultivars with new favorable allele and allele combinations, resulting in a reduction of the rice vulnerability to biotic and abiotic stresses, increasing the yield and the food security of the Brazilian population.
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MENDONÇA, João Antônio. Cruzamento dialélico de genótipos da mini-coleção nuclear de arroz da Embrapa. 2011 91 f. Dissertação (Mestrado em Genética e Melhoramento de Plantas. Universidade Federal de Goiás, Goiânia.