Genetic variability and character association among morpho-metric traits and essential oil constituents in eight half-sib seed progenies of peppermint (Mentha piperita L.)

Menthol rich with low menthofuran peppermint (Mentha piperita L.) genotype MPK-5 and their eight half-sib seed progenies were evaluated for different genetic parameters, namely coefficient of variation, genetic advance, heritability, associations, and path analysis for different economic characters, viz., plant height, leaf length, leaf width, leaf: stem ratio, herb yield, essential oil content (%), and contents of various essential oil constituents (quality traits) such as α-pinene, β-pinene, sabinene, myrcene, limonene, 1,8-cineole, menthone, menthofuran, neo-menthol, isomenthone, menthyl acetate, menthol, and pulegone. The phenotypic coefficient of variations (PCV) was found slightly higher than the genotypic coefficient of variations (GCV) for the characters studied, indicating that the apparent variation was not only due to genetic but also influenced by the growing environment for the expression of studied traits. The highest genotypic coefficients of variation (GCV) was noted for the character pulegone, followed by menthofuran and 1,8-cineole. High heritability coupled with high genetic advance was observed for menthol followed by pulegone demonstrating that these chemical compositions might be under non-additive genetic control. The genotypic correlations were higher than the phenotypic correlations for studied traits. The significant and positive associations of β-pinene with sabinene and 1,8-cineole; α-pinene with β-pinene, sabinene, and 1,8-cineole; menthyl acetate with neo-menthol; and sabinene with 1,8-cineole were noted. A high direct positive effect was also recorded between menthofuran and limonene.