Improvement in growth parameters and essential oil content and characteristics of populations derived from intraspecific crosses of Mentha spicata and M. longifolia

Populations derived from intraspecific crosses within two mint species of Mentha spicata and M. longifolia, were studied for genetic and phenotypic coefficients of variation, heritabilities, and genetic advances in various traits including plant height, fresh and dry weights, number of branches per plant, plant canopy diameter, leaf area, and essential oil content and yield. The majority of agro-economic characters showed high heritability (h(2)) and genetic advances in the F-2 generation. The maximum genetic advance and genotypic coefficient of variation were recorded for fresh weight, leaf area, and essential oil content and yield. Based on these traits, total flavonoid (TFC) and phenolic (TPC) contents of the best genotypes from each species of M. longifolia and M. spicata were estimated. The results showed that some of the F-2 plants had a higher amount of TFC and TPC compared with the parents. The analysis of essential oil components also revealed that the amount of piperitenone and menthone in M. longifolia and carvone and limonene in M. spicata significantly increased in the selected genotypes derived from intraspecific crosses. It is hypothesized that the improvements in the offspring derived from intraspecific crosses of mint are attributed to transgressive segregation and heterosis. Therefore, crossing within mint species can be effectively utilized for recombination breeding to obtain genotypes with a novel genetic structure potentially usable in breeding programs for pharmaceutical purposes.