Seleção em populações de trigo visando tolerância ao estresse de calor

• Autor(a) principal: Oliveira, Davi Melo de
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4474
• topic: Triticum aestivum; Altas temperaturas; Índices de seleção; Triticum aestivum; High temperatures; Selection indexes; seleção; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

Brazil is very dependent of the importation of wheat, producing less than 50% of the national demand. This bothering position lacks for measures that aim the increase of the production, as the increase in the productivity and expansion of the planted area. The Central-Brazil Region presents great potential for expansion of the wheat crop, however it is characterized by raised temperatures, that is a serious limitation for the wheat crop in some locality. Moreover, climatic changes resulting of the global warming will be able to impose restrictions to the wheat crop. About this, tolerant genotypes to the heat are important for ample adaptation to environments with high temperatures stress. Objectifying to detect genetic variability for heat tolerance between genitors, segregating populations, and families of wheat; to quantify the effect of high temperatures on genotypes of wheat and; to evaluate the gains predicted with selection indexes, were lead two experiments in the experimental area of the Universidade Federal de Viçosa. The experiments had been sown on February (heat stress) and June (no heat stress) of 2007. In the first experiment F2:4 families were evaluated and in the second one, F2:5 families. Two hundred forty families and 16 genitors were evaluated in a square lattice design 16x16, with two replications. The characters flowering, plant height, grain yield and thousand grain weight were recorded. All evaluated characters presented reduction under high temperatures, being the grain yield the more affected character. There genetic variability for heat tolerance between genitors and wheat segregating populations. The most heat tolerant genotypes were the genitors 2 (BR 24), 3 (Aliança) and 4 (EP 93541), and the segregating populations 1 (BH1146/BR24//Aliança/EP93541), 2 (BR24/Aliança//EP93541/CPAC9662) and 3 (Aliança/ EP93541//CPAC9662/Pioneiro). The simultaneous gains prediction for all the characteristics made possible, being the indexes of Mulamba and Mock, Pesek and Baker and Kempthorne and Nordskog the ones that make possible gains in the desired directions for all the characters. The bigger predict gains in plant height were made possible with the Pesek and Baker index. Desiring to get the gain maximum in grain yield, without modifying the plant height, the Kempthorne and Nordskog index is the most efficient.