Estratégias de condução de populações segregantes no melhoramento genético do feijoeiro / Driving strategies of segregating populations applied in genetic improvement of commo bean

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

In agreement with the convenience of the breeders, some modifications can be made in the traditional methods of conductions of the populations segregating. In bean, a common strategy used by breeders is the aspect selection for grain from early generations. Therefore, the aspect of grains is an important feature to obtain new cultivar. However, there is little information regarding the effect of such selection on other characteristics, especially when it is practiced in each generation. The present study aimed to evaluate the efficiency of method bulk whit selection by comparing it with traditional bulk and SSD, and evaluate the effect of selection for the advancement of segregating populations on other characteristics of interest. Therefore, we used the population from the cross between the cultivars Ouro Negro and Meia Noite, which was conducted by three methods. In the bulk whit selection (bulksel) selection was performed to grain in each generation. To compare the effectiveness of the current methods under study, were conducted two independent experiments: the first was to evaluate the population in generations F4 to F8 conducted by three methods, and the second experiment was to evaluate the families that derived from each method. In the first case the experiment was conducted in the dry season of 2008, the cities of Coimbra and Florestal, in Minas Gerais. The experiment was delineated according to a factorial scheme 3 x 5 + 4, three methods (bulk, bulksel and SSD), five generations (F4 to F8) and four checks in a randomized block design with four replications. We evaluated the productivity, thousand grain weight and percentage of grain pattern of Ouro Negro cultivar. In the second experiment it was evaluated 131 families derived from each method in the F6 generation and seven cheks, a total of 400 treatments. The families were evaluated at the experimental station of Coimbra in Minas Gerais during the seasons of winter/07, dry/08 and winter/08. A triple square lattice design was applied. It was evaluated the productivity, the appearance of grain, the severity of rust and plant height. In the evaluation generations, it was observed that the bulksel was appropriate method that provided the best results, with higher average yield and thousand grain weight and, most importantly, the percentage of grains with the Standard Ouro Negro. Regarding the assessment of families from each method, the bulksel also stood out. This method provided the greatest number of families among the most productive and of best appearance of grains, surpassing, in some cases, the average of the best parent (Ouro Negro). The behavior of families for resistance to rust and plant bearing, in general, the methods didn t differ significantly. In both experiments, it was found that selection for grain with the advanced generations did not affect the genetic variability for grain yield. Bulksel method proved to be an effective strategy in the genetic improvement of common bean, especially when it is wanted improvement in terms of aspect of grains.

ASSUNTO(S)

bulk ssd seleção precoce métodos de melhoramento ciencias agrarias ssd melhoramento do feijoeiro improvement methods phaseolus vulgaris early selection bulk improvement of bean phaseolus vulgaris

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