Análise dialélica e heterose como ferramenta para seleção de genitores de trigo para o ambiente de terras baixas

Abstract

Wheat is an important cereal consumed worldwide, in Brazil the cultivated area and production are growing, however the country still depends on the foreign market to supply the demand for the product. The path to self-sufficiency is related to the development of new cultivars adapted to different edaphoclimatic regions, as well as the expansion to new agricultural frontiers. Diallel analysis is an excellent alternative for selecting parents, it allows defining better combinations between parents and also allows the identification of promising crosses. The objective of this work was to analyze the combining ability and estimate heterosis as a tool for selecting wheat parents through an F2 segregating population, for the lowland environment. Six parents were evaluated, BRS Reponte, Fundacep Horizonte, ORS Ametista, TBIO Bandeirante, TBIO Sintonia, CD 1705 and the segregating populations of the partial diallel, the variables were ear weight (PE), in grams, number of grains per ear (NGE) and grain weight (PGE), in grams. The data were subjected to analysis of variance, the results of the sum of squares were decomposed into general and specific capacity, after comparing means, heterosis was determined. For general combining ability, the cultivar BRS Reponte had the highest averages and presented positive estimates for all characters, the parents CD 1705 and Fundacep Horizonte had positive estimates for PE and PGE characters. With regard to heterosis for the PE variable, the TBIO Bandeirante X TBIO Sintonia, TBIO Sintonia X CD 1705, ORS Ametista X TBIO Sintonia and Fundacep Horizonte X ORS Ametista populations showed positive values, for the NGE variable, only the BRS Reponte X CD 1705 population showed a negative effect for heterosis, for the PGE variable, the populations TBIO Bandeirante X TBIO Sintonia and TBIO Sintonia X CD 1705 showed positive effects for heterosis. Regarding the specific combining ability for PE and NGE variables, several segregating populations showed positive estimates, that is, with increment in values, for the NGE variable, the populations BRS Reponte X Fundacep Horizonte, BRS Reponte X ORS Ametista, BRS Reponte X TBIO Bandeirante, BRS Reponte X TBIO Sintonia, Fundacep Horizonte X ORS Ametista, Fundacep Horizonte X TBIO Bandeirante, Fundacep Horizonte X TBIO Sintonia, Fundacep Horizonte X CD 1705, ORS Ametista X TBIO TBIO Bandeirante, ORS Ametista X CD 1705, TBIO Bandeirante X TBIO Sintonia, TBIO Sintonia X CD 1705 presented positive estimates, for the PGE variable the populations Fundacep Horizonte X ORS Ametista, TBIO Bandeirante X TBIO Sintonia, TBIO Sintonia X CD 1705 had positive estimates. Therefore, the parent BRS Reponte showed productive potential and together with the parents, Fundacep Horizonte, CD 1705 and BRS Bandeirante can be used in crosses, the segregating population TBIO Sintonia X CD1705 has potential for generation advancement and the combinations BRS Reponte X ORS Ametista, ORS Ametista X CD 1705 can develop promising genotypes for PE, PGE and NGE.