Variations in essential oil composition of fourteen released Mentha arvensis L. varieties harvested at four different developmental stages for determining optimum crop-age for harnessing maximum oil yield in Indo-Gangetic plains

India has emerged world leader, with a substantial share of 80–85 %, in the natural production and overseas trading of mint oil and its derivatives. This has been possible because of the concerted efforts of CSIR-CIMAP that has revolutionized the mint cultivation in India through development of superior agro and processing technologies, superior plant varieties, and popularization through its routinely organized seminars, training programs, and exhibitions such as ‘Kisan Mela’ for farmers. Till date, 14 varieties of Mentha arvensis are available to farmers for commercial cultivation. The essential oil composition of all the commercial varieties of Japanese mint grown in India is well known but knowledge on the variation in herb and essential oil yield, as well as variation in relative proportion of the major constituents in the essential oil with crop age is completely lacking. To address these gaps, the present study was designed where estimates of phenotypic and genotypic variance (σ 2 p and σ 2 g), phenotypic and genotypic coefficients of variance (PCV and GCV), genetic advance (GA), broad sense heritability ( h bs 2 ) and genetic advance as percent of mean (GAM), correlations and path analysis studies were conducted to assess the variability and breeding potential in all of 14 commercially cultivated varieties. The results of the present study also helped in identifying and classifying the varieties as very early maturing (Var. Gomti in 70 days), early maturing (vars. Saksham, Kosi, CIM-Saryu, MAS-1, CIM-Kranti, Damroo, CIM- Unnati in 90 days), late maturing (vars. Himalaya, Kalka, Shivalik, Kushal, Sambhav). • Timely harvesting is crucial in determining quality and quantity of mint oil. • The oil content (%) tends to increase in Mentha arvensis with crop age. • The variety Gomti matures earliest in 70 days. • Harvesting vars. Saksham, Kosi, Saryu, MAS-1, Kranti, Damroo, Unnati at 90 days is recommended. • The vars. Himalaya, Kalka, Shivalik, Kushal, Sambhav completely mature in 120 days.