Capacidade combinatória e modificações de ambiente na expressão dos componentes do rendimento de grãos e da qualidade industrial em trigo.

• Autor(a) principal: Schmidt, Douglas André Mallmann
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFPel - Guaiaca
• Texto Completo: http://repositorio.ufpel.edu.br/handle/ri/1153
• topic: Triticum aestivum, L.; Capacidade geral de combinação; Capacidade específica de combinação; Rendimento de grãos; Triticum aestivum, L.; General combining ability; Specific combining ability; Grain yield.; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA

In plant breeding programs, parental selection is a very important step. The selection of parents to be used to obtain the segregating populations can determine the success or failure in achieving genetic gains. Diallel analysis has been used to determine the general and specific combining ability and to aid the selection of the most promising combinations. The fitting of genotypes to environmental conditions that allow the expression of full genetic potential for the target characters, has shown great importance to maximize wheat grain yield and quality. In this sense, the main objective of the study was to determine the combining ability of wheat genotypes, and their performance for grain yield components and industrial quality traits in different environments under different nitrogen levels. Six parents were employed in diallel analysis, including reciprocal crosses, to evaluate general and specific combining ability of agronomic traits. The diallel cross experiments were conducted in Capão do Leão County/RS in 2007 and the experiment evaluating nitrogen levels was conducted in environments of Capão do Leão County in 2006 and 2007, and Ijuí County in 2007, both located in Rio Grande do Sul State. The nitrogen doses used were 0, 40, 80 and 120 kg ha-1 as cover fertilizer. The mean squares for general combining ability were greater than those for specific combining ability for the characters number of grains per ear, grain weight, number of ears per plant and grain yield per plant. Additive gene action was likely to more intensely affect these characters. It was possible to verify effects of heterosis, mostly for the character grain yield per plant with results above 100% of mean heterosis. The high heterosis values in F1, when associated with high advanced generation bulk yields in, increases the likelihood of obtaining high yielding genotypes by the increase of recombinant genotypic classes. Maternal and extrachromosomal effects were very intense, suggesting that breeding programs should pay attention to which parent is used as pollen donor and vice-versa. Different responses to nitrogen fertilization were observed regarding grain yield. The nitrogen fertilization promoted increases in the rates of lodging in all genotypes tested in the three environments. In environments with high yield potential, the increase in the level of nitrogen, did not increase gluten strength. Bread wheat genotypes better respond to nitrogen availability increases. On the other hand, genotypes with low gluten strength did not respond to nitrogen increases.