Ganhos genéticos via índice de seleção e modelos mistos em amendoim indicado para o semiárido

• Autor(a) principal: Ramos, Jean Pierre Cordeiro
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/123456789/15817
• topic: Arachis hypogaea; Variabilidade; Melhoramento; Procedimentos de seleção; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA

Peanut is an important leguminous at worldwide, widely cultivated in Brazil, mainly in Southeast region. The Northeast have potential for peanut crop, although face the climatic limitations, such as high temperatures and water deficit that could hazard the production. The improvement of cultivars adapted to these conditions is one of the main strategies adopted by breeders in order to leverage the crop in this region. The adoption of statistical tools are essentials, due provide estimates of the proportions of each variation source found in trials. The genetic variance, the coefficient of genetic variation, the heritability and the selective accuracy are the main estimators, meaning a basic assumption for selection procedures and consequent genetic gains. In this work, we estimated the gains obtained through selective practices in peanut genotypes, which findings are reported in two chapters. The first one reports on the selection gains of peanut families RC1F3, resulting from crossing between synthetic amphidioid (A. batizocoi K9484 x A. duranensis SeSn 2848)4x and a commercial cv. BR1 (A. hypogaea subsp. fastigiata), submitted to moderate water suppression aiming to selection of drought. Thirteen RC1F3 families were grown in the field and submitted to 21 days of water suppression. Two early and drought-tolerant cultivars (BR1 and Senegal 55 437) were used as tolerant controls. Eight agronomic traits were adopted to characterize the materials. The mixed models (REML / BLUP) and rank index selection index, proposed by Mulamba & Mock, were uses as selection procedures. We found a relative predominance of residual variance to the detriment of genotypic variance, meaning existence of segregation within the families. High accuracy values were found for most traits. Of the 13 families evaluated, three highlighted based on agronomic traits, with gains for: number of pods/plant, pod length and number of seeds/pod, and also increase of earliness in, at least, 1 day. The second chapter aimed to estimate the selection indexes and economic weights that enable maximum genetic gains in runner peanut. Eleven genotypes were evaluated through nine agronomic traits. The indices used were: Smith and Hazel (SH) classic index, Pesek and Baker (PB) index, Williams base index (W), Elston index (E), Subandi et al. index (S), Cruz index (GI), and the Index based on Sum of Ranks of Mulamba and Mock (MM). The economic weights were: main traits (MT), weight 1 (W1) for all the traits, coefficient of genetic variation (CGv), genetic standard deviation (GSD) and "B" coefficient, obtained through multivariate regression. We found a significant effect of genotypes for all traits (p<0.01), meaning genetic variability among materials. High heritability values were found for most traits (above 90%), indicating genetic progress with selection cycles. The SH-MT, SH-W1, SH-GSD, W-W1 and W-GSD combinations, followed by MM-MT, MM- x CGv, MM-GSD, GI-MT, GI-W1, GI- GSD and E, indicated higher gains for traits related to production, but with unsatisfactory values for Blooming and Cycle. In general, the Mulamba and Mock index was the most promising when applied with W1 in all traits. It was able to balance gains close to the maximum limits obtained through direct selection, for both production and earliness traits.