Resumo

MORALES NIETO, Carlos Raúl et al. Phenotypic and molecular characterization of populations of arizona cottontop [Digitaria californica (Benth.) Henr.]. Rev. mex. de cienc. pecuarias [online]. 2012, vol.3, n.2, pp.171-184. ISSN 2448-6698.

Phenotypic and genotypic diversity were explored and characterized in arizona cottontop [Digitaria californica (Benth.) Henr.] populations at Chihuahua state grasslands. Principal component and cluster analysis were applied to the data using Ward method. There were differences (P<0.05) within variables and high phenotypic and genotypic diversity were detected among populations. Three principal components explain 79 % of the variation on 91 ecotypes. For the PC1, shoots number, biomass and forage height were the variables contributed on morphological diversity. Those variables are related with forage production and regrowth. When analyzing the correlation of PC1 with forage yield, was observed that as stem density increased, forage yield was also increased at about the same proportion (r = 0.94, P<0.01). A similar effect occurred on the forage yield with forage height (r= 0.77, P<0.01), plant height (r= 0.72, P<0.01) and tiller diameter (r= 0.72, P<0.01). According with Ward method, five groups were detected. Molecular markers showed 179 bands which represents 86.3 % of the polymorphism (154 bands) and 13.7 % of the monomorphysm (25 bands). Polymorphic bands were 38, 38, 38, and 40 for EcoRI-AAG + MseI-CTG, EcoRI-ACT+MseI-CTG, EcoRI-AGG + MseI-CAG y EcoRI-AAC + MseI-CAG combination, respectively. The AFLP discriminated the 30 populations evaluated with similitud values between 0.14 and 0.55. Ecotypes PB-270 and PB-277 in one side and PB-313 and PB-337 had the highest genetic heterogeneity; they have the lowest similitude (0.14). Ecotypes with high forage potential, based on morphology and genetic variability, were identified (ecotypes 505 y 596).

Palavras-chave : Digitaria californica; Phenotypic variation; Molecular variation; Genetic resources.

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