Progresso genético em três ciclos de seleção recorrente para tolerância ao calor em trigo

• Autor(a) principal: Assis, Josiane Cristina de
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1329
• topic: Triticum aestivum L.; Calor; Ganho; Seleção; Triticum aestivum L.; Heat; Gain; Selection; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL

The objectives were to estimate the genetic progress in three recurrent selection cycles and predict the genetic gains in the selection process in the third cycle of recurrent selection in wheat for tolerance to heat by using different selection strategies.The families of the cycle 0 were evaluated at the Experimental Station of Coimbra, belonging to UFV. The families of the first cycle of selection (cycle I) and the second cycle (cycle II) were evaluated in field experimental Prof. Diogo Alves de Melo, in the field of agronomy at UFV. We evaluated grain yield in all three cycles. In all evaluation of the families were the analysis of variance and the estimates of genetic and phenotypic parameters. We estimated the genetic progress for yield after three cycles of the three recurrent selection. As the cycles in different years, we used the performance of two groups that were present in all evaluations to mitigate the environmental effect in the estimates. The difference between the b's linear regression between the number of cycles, independent variable (x), and the average performance of the character under selection, the dependent variable (y), the progeny and witnesses, provided the estimate of genetic progress. To the prediction of genetic gain in the progenies of the third selection cycle, we used four strategies: truncated selection on grain yield (GY), Classic Index of Smith and Hazel, Index Rank Sum and Standardization Z Index. The characters included in the indices were: GY, ear number, grain weight per ear, grain weight and harvest index.The genetic progress by recurrent selection was 8.4% after three cycles of recurrent selection for grain yield. The existence of genetic variability among families, especially in the last cycle, suggests the possibility of continuous success with the selection in subsequent cycles.The predicted gains for grain yield with the use of different selection strategies in the progenies of the third selection cycle ranged from 16.2to 18.8%.There was good agreement in the selection of progenies of the third cycle of recurrent selection with direct selection and the indices and Hazel-Smith, Sum of Ranks and Z sum of the standardized variables.