Causas de correlação entre caracteres e efeito de ambientes na predição do potencial de populações segregantes no melhoramento do feijoeiro

• Autor(a) principal: Rocha, Gilmar Silvério da
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1353
• topic: Feijão; Produtividade de grãos; Melhoramento; Correlações; Bean; Grain yield; Breeding; Correlations; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL

The objectives of this work were to determine the causes of the associations between characters related to plant architecture and grain yield and their implications in the common bean plant breeding; to verify the effect of environments on the prediction of the genetic potential of the common bean plant populations regarding hypocotyl diameter and grain yield by the Jinks and Pooni method; and to verify the consistency of predicting the potential of these populations during the winter and dry seasons, using the methodologies of Jinks and Pooni and m+a and d. Forty-eight populations were evaluated in the 2009 winter season (F2 and F3 generations, simultaneously) and 2010 dry season (generations F3 and F4, simultaneously). As controls, 14 parents were used, besides the cultivars Pérola and BRSMG Talismã. The experiments were conducted at the experimental field of the Universidade Federal de Viçosa in Coimbra, MG, and was arranged in a randomized block design with three repetitions, with the plots being constituted of four 4 m long, 0.5 spaced lines. To determine the causes of associations between characters of the common bean plant, the following characters of the populations and controls were evaluated: hypocotyl diameter, plant architecture, plant mean height, 100-grain mass, and grain yield; phenotypic, genotypic and environmental correlations between these five characters were also obtained. A prediction of the potential of the segregating populations was made by the Jinks and Pooni methodology and by the estimates of the loci contribution in homozygosis (m+a ) and heterozygosis (d), using the grain yield and hypocotyl diameter data. This last character was measured in 20 plants randomly taken from the plots. Regarding the associations related to the characters plant architecture and grain yield, high and significant phenotypic and genotypic correlations between the characters hypocotyl diameter, plant architecture, and plant mean height were observed, both in the lines and populations of different generations, indicating that these associations are caused by pleiotropic genes of additive effect. As for the correlations of the characters hypocotyl diameter, plant mean height, and plant architecture with the characters grain yield and 100-grain mass, these are caused by the different linked genes, since these associations were surpassed as generations advanced. The characters hypocotyl diameter and plant mean height were found to be effective indicators of the common bean plant architecture. Based on the magnitude and signals of the correlations obtained in the populations, it can be confirmed that the evaluation of families derived from more advanced generations, in experiments with repetitions, is a promising strategy for the development of productive and erect bean plant lines, with commercially acceptable grain size. The probability of the populations to originate lines superior to line A805 in 10%, considering the hypocotyl diameter and cultivar Perola in 35% for grain yield, were inconsistent when comparing the different generations, evaluated in different seasons, for most of the populations. Due to the low coincidence between the best and worst populations, in the two crop seasons and different generations for the two characters, it became evident that the effect of environments interferes in the choice of common bean plant populations, when applying the Jinks and Pooni method. Thus, when using this methodology, it is recommended to evaluate populations in as many types of environment as possible. The correlation among the population means in the winter and dry season crops was significant and of a reasonable magnitude for the characters hypocotyl diameter and grain yield, while the correlation between the variances of these populations for the two season crops was inexpressive, indicating greater influence of the environmental effects on the variance estimates than on the mean estimates. A low correlation between the pairs m+a (winter season) x m+a (dry season) and d (winter season) x d (dry season) for hypocotyl diameter and grain yield was confirmed, evidencing that these estimates are also influenced by the environments.