Depressão endogâmica e variabilidade genética de populações para produção de milho verde
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2020-03-30
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Universidade Federal de Goiás
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The production of vegetable corn is an activity of great importance for several regions of Brazil. Despite this, breeding programs have devoted little effort to developing and recommending cultivars specifically for this purpose. Then, it is essential that programs for the improvement of public institutions seek to serve this niche market, which has a relevant social role, as it is conducted mainly in small areas. This work aimed to estimate inbreeding depression and the genetic components of three populations for the production of vegetable corn. The populations evaluated have a different genetic basis: a variety of open pollination, called UFG-Samambaia (P1), a population obtained by crossing two older hybrids (P2) and a third population obtained by crossing of the modern hybrids (P3). Progenies of these three populations were obtained by sampling self-fertilized S0 plants. S1 progenies, three S0 populations and two checks were evaluated in a triple lattice 14 x 14 with plots of a four meter line. They were evaluated the agronomic traits: ears weight, plant height, ears height, relative position of the ear, breaking and lodging plants, days to anthesis, days to silking; and quality traits of ears: mass weight, ears weight without straw, length of ears without straw, ears diameter, ear alignment, ear stuffing, grain color. Statistical analyzes were performed using a mixed model approach. Inbreeding depression was estimated for all characters and the components of means (m + a ’and d) and variance. Genetic variability was observed for most traits among P1 progenies. The progenies of the P2 and P3 populations did not show genetic variability for most characters. The three populations suffered an impact when subjected to self-fertilization due to the effects of inbreeding. Inbreeding depression in P1 has higher rates for most characters: plant height, ear height, relative ear position, mass weight, length of ears without straw, alignment of ears and stuffing; In P2, the male flowering characters, weight of ears without straw and diameter of ears show a higher index and in P3, the characters of ear weight, female flowering, breakage and lodging and grain color. In general, the
quality characters of the ear, important for the production of green corn, the greater depression due to inbreeding than the agronomic characters. This shows that, inbreeding depression must be considered in the selection process, with the frequency of favorable alleles increasing throughout the improvement process.
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CASCÃO, L. M. Depressão endogâmica e variabilidade genética de populações para produção de milho verde. 2020.46 f. Dissertação (Mestrado em Genética e Melhoramento de Plantas) - Universidade Federal de Goiás, Goiânia, 2020.