Análise de trilha para carotenoides em milho

Abstract

Path analysis for carotenoids in maizeAlthough aspects of magnitude and significance are considered, the study of correlations between traits, alone, does not necessarily guarantee a cause and effect relationship between them. Therefore, the objective of this study was to use path analysis to allow the unfolding of correlations in direct and indirect effects, considering the carotenoids profile of maize genotypes. Data was obtained from the national assay of maize cultivars conducted by Embrapa Maize and Sorghum in the 2004/2005 growing season, with means of ten genotypes in five environments. The contents of total carotenoids (CT), alpha and -carotene, lutein, zeaxanthin and -criptoxantin were evaluated. Xanthophyll zeaxanthin provided the highest direct effect on -carotene. The high correlations between -carotene and total carotenoids and between -carotene and -criptoxanthin are due the indirect effect via zeaxanthin. The direct selection of genotypes with high levels of -carotene appears as a more effective alternative, but if other fractions of carotenoids were also considered, methods of simultaneous selection of characters using selection indices are more efficient in obtaining genotypes with high levels of -carotene than the correlated response.

Path analysis for selection of feijoa with greater pulp weight

“…This suggested that the two methods were accurate in estimating the direct and indirect effects (CRUZ & CARNEIRO, 2006;RIOS et al, 2012). This similarity between the performance of the two methods of path analysis was due to the low degree of multicollinearity (CN = conditions number = 209.7), being close to the limit considered as weak, CN<100 (MONTGOMERY & PECK, 1981).…”

“…This technique avoids the exclusion of explanatory variables to maintain multicollinearity at acceptable levels. (CRUZ & CARNEIRO, 2006;RIOS et al, 2012). For comparison purposes, a second single chain path analysis method (with no multicollinearity control) was performed, since the CN was close to the lowest limit to be considered weak multicollinearity (CN<100).…”

Contribution of morphoagronomic traits to grain yield and earliness in grain sorghum

“…The understanding of the correlation between the characteristics under study at the initial stages of a breeding program is of great importance, especially in cases where the characteristic of interest exhibits low heritability and is difficult to measure (Rios et al, 2012). Assessing the direct and indirect effects is dependent on the traits set under study, which is usually established by the researcher's previous knowledge and possible interrelationships expressed in path diagrams (Cruz et al, 2014).…”

“…In breeding programs, the knowledge of the direct and indirect effects of the explanatory variables on a principal trait might help in deciding on to use a correlated response or progress in selection (Rios et al, 2012). Despite the importance of this analysis, studies that used path analysis in sorghum are scarce.…”

Análise de trilha em caracteres de frutos de jabuticabeira

“…Assim, há duas estratégias básicas para a análise de trilha: identificação e exclusão de variáveis responsáveis pela colinearidade; ou análise de trilha com regressão em crista, no caso de não se desejar a eliminação de variáveis. Nesta segunda estratégia, utiliza-se uma constante k, cujo valor deve ser o menor possível, para estabilizar os coeficientes de trilha e manter o fator de inflação da variância (VIF) menor que 10, em todas as variáveis explicativas (Cruz & Carneiro, 2006;Rios et al, 2012).…”