Abstract
Grain yield is a complex quantitative trait, because its expression is associated to the large number of genes with small effect. In addition, there is interaction among different yield components and environment effect, making difficult the direct selection of genotypes. The most viable alternative for wheat breeding programs, an autogamous plant, is use artificial crosses in order to obtain superior genotypes. Hybridization after use of successive self-fertilizations results in segregating populations, which reveal the genetic variability, especially when the parents are genetically different. Therefore, it is important to know genetic relationships between crosses, which will serve as reference for decision making in the choice of combinations. Therefore, general combining ability (GCA) and specific combining ability (SCA) are used, which facilitate choice of the best parents to compose crossover block. In addition to these parameters, path analysis can be used to determine importance of primary and secondary traits and to guide indirect selection of promising genotypes by means of interest traits.
Highlights
In quest for greater yields, wheat breeding programs tend to identify combinations ability and associations between yield traits, in order to facilitate selection of genotypes with the desired trait
It is known that grain yield is considered a quantitative character of high complexity, due to its influence by several genes and to be involved by combination of numerous components, making it difficult the direct selection of genotypes by low heritability that it presents (Silva et al, 2005; Gondim et al, 2008)
Correlation knowledge among traits is of great importance for the genetic improvement, making it possible to quantify how much a trait can influence others and to determine traits for indirect selection of genotypes
Summary
In quest for greater yields, wheat breeding programs tend to identify combinations ability and associations between yield traits, in order to facilitate selection of genotypes with the desired trait. It is known that grain yield is considered a quantitative character of high complexity, due to its influence by several genes and to be involved by combination of numerous components, making it difficult the direct selection of genotypes by low heritability that it presents (Silva et al, 2005; Gondim et al, 2008). Correlation knowledge among traits is of great importance for the genetic improvement, making it possible to quantify how much a trait can influence others and to determine traits for indirect selection of genotypes. Phenotypic correlation between traits is little used in plant breeding because it is result between environmental with genetic factors interaction. Genetic correlation presents satisfactory results considering only traits with high heritability allowing its use in breeding programs (Oliveira et al, 2007).
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