Melhoramento de milho para eficiência no uso de nitrogênio

• Ano de defesa: 2007
• Autor(a) principal: Souza, Leandro Vagno de
• Orientador(a): Miranda, Glauco Vieira
• Banca de defesa: Carneiro, José Eustáquio de Souza , Coimbra, Ronaldo Rodrigues , Souza, Moacil Alves de , Vieira, Rogério Faria
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Melhoramento; Estresse abiótico; Milho
• Palavras-chave em Inglês: Breeding; Abiotic stress; Maize
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1277

The objectives were to determine the genetic control of nitrogen use efficiency (NUE) in environments with and without stress of nitrogen; evaluate the effects of the stress of nitrogen in the estimates of general ability (GCA) and specific ability (SCA) combining; identify the genetic control of agronomic characteristics of cultivars of maize in contrasting environments as to the application of nitrogen and phosphorus; predict the expected gains with a cycle of selection half-sib families of the population of maize UFV 8 in environments with and without stress of nitrogen. For that, were evaluated, in 2003/04 and 2004/05, hybrid combinations between eight cultivars of maize in a cycle of selection among half-sib families of the population of maize UFV 8, respectively. The tests were conducted in the Experimental Station of Coimbra, MG. In the 2003/04 season, were installed two tests, the first with high or low nitrogen and second with combinations of high and low nitrogen and phosphorus. In 2004/05, the cycle of selection was performed with and without stress of nitrogen. In the first test of 2003/04, for yield, (PG) in the absence of stress, were verified significances to GCA and (SCA). In stress, there was no significant effect. As for the efficiency of absorption of nitrogen (EAbN), the environment without stress there has been significant effects both for CGC and for the SCA and stress only for GCA. For the efficiency of the utilization of nitrogen (EUtN), in both environments, the CGC and SCA showed no significance. For (NUE) was significance to CGC and SCA only in the absence of stress. In the second test 2003/04, it was found that the sign of the genetic correlation of the secondary characteristics with PG, did not differ between the environments of high and low N recital low P. However, the correlations were change in the signal between the environments of high and low P. In high P, the GCA was significant only for PG at high N, showing that for this feature the additive genetic effects were differentiated between environments with and without stress of nitrogen, separate from the behavior occurred in low P, where GCA presented significance both In high as below N. In the 2004/05 harvest, it was found that the genetic correlations of the characteristics final stand, prolificacy and volumetric weight to the productivity of grain had signs opposing between environments. The heritability for grain yield, stand, plant height and spike suffered cuts below N. The genetic variability between households, half-sib families of the population UFV 8 was less stress on the environment. Gains predicted with the selection of 10% of the best families of half-sib families were differentiated between environments. The effect of nitrogen stress in families selected in the high N was higher in relation to the effect of stress on families selected in the low N. It is concluded that the genetic control of efficiency in the use of nitrogen varies with the availability of nitrogen, and the inter- relationship between nitrogen and phosphorus influence the genetic control of yield and the genetic correlations of secondary characteristics with PG; estimates of earned predicted, genetic parameters and genotypic variability are influenced by the stress of nitrogen and the expected gain is less stress in environments with nitrogen.