UFV Journals (Universidade Federal de Viçosa)
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Consequences of early selection for grain type in common bean breeding
Full text linkThe common bean grain color is controlled by a large number of genes, probably distributed in all the chromosomes. Therefore, early selection for this trait is likely to cause an expressive reduction in the variability of other traits such as grain yield, which is the main objective of most breeding programs. This study was carried out to verify the effect of early (F2 generation) selection for grain type on grain yield in more advanced generations. The F2 population from the cross between the Ouro Negro (black grains) and Pérola (“carioca” – cream with brown stripes) type grains was used. The harvest seeds were divided into two groups, one with “carioca” grains and another of mixed type, where no selection was applied. The F3 plants of both sub-populations were individually harvested resulting in 199 families per sub-populations. These 398 F3:4 families and the parent cultivars were assessed during the year 2000 dry season in Lavras and the F3:5 families in the winter of 2000 in Lavras and in Patos de Minas. On average, no yield differences among the non-selected and selected for grain type family means were detected. It was also observed that the heritability estimates were high and similar. It is, therefore, inferred that early (F2 generation) selection for grain type did not reduce the potential of the population for selection of superior inbred lines. Consequently, strong selection for grain color in the F2 generation, to screen out undesirable types will enable breeders to concentrate their efforts on the selection of other traits in the advanced generations. Only families with commercially acceptable grain type will be submitted to selection, increasing the chances of success
Banana breeding program at Embrapa
Full text linkThe principle factors related to the banana breeding are described: botanic classification, cultivars, origin and evolution of the banana, reproductive systems, sterility and partenocarpy, polyploidy, inheritance of characteristics. To solve the problems caused by fungus, bacteria, virus, nematodes and insects, high stature and low productivity of some cultivate, it has been used the creation of new resistant varieties by means of the genetic program. The breeding program consisting of the following stages: formation, characterization and evaluation of wide germoplasma collection, introduction and selection of clones, improvement for hybridization, improvement for mutation, somatic hybridization and genetic transformation. The principle results obtained in the breeding program are: the morphologic characterization of the germoplasma, allowing the identification of promising genotypes and its recommendation to the producers; the obtainment of resistant hybrid tetraploid (Pome type) to the yellow and black sigatokas and to the Panama disease, with reduced stature and cycle and high productive; the genetic improvement of diploid AA, whose pollen has been used in the improvement of the commercial cultivars and for the own hybrid diploid; the evaluation of the cultivars and hybrid in different ecosystems, allowing to identify potential varieties to be recommended as a local and national status for several ecosystems; obtainance of hybrid of Silk cultivar (AAB) with the diploid (AA) ‘Lidi’, by means of the employment of somatic hybridization for eletricfusion, although, none cultivar was obtain from this technique
Stability of Genetic Divergence among Eggplant Accesses in Three Stages of Development
Full text linkGenetic divergence stability among 19 eggplant accesses was estimated in three stages of development: vegetative, reproductive and productive. The experiment was carried out in a randomized block design, with three replications and four plants per plot. For each developmental stage, the divergence was calculated from 12, 12 and 5 characteristics, respectively. The cluster analysis, applied to the genetic distance matrix (D2), showed the formation of two clusters in the vegetative stage, four in the reproductive stage and six in the productive stage. Therefore, it was obseved that productive stage characteristics have greater discriminatory capacity. However, inconsistency in respect to the number and composition of clusters formed in different stages was observed. It can be concluded that the genetic divergence estimated among accesses is related only to the variability of the characteristics used in its estimation, and that extrapolation of this variability to other characters may lead to wrong interpretations
BRS 185 Soybean
Full text linkBRS 185 is a soybean cultivar developed by Embrapa Soybean for sowing in Parana State. It flowers and reaches maturity 53 and 121 days after germination and yields 3,090 kg/ha. BRS 185 is resistant to stem canker, frog-eye leaf spot, bacterial pustule and moderately resistant to powdery mildew