Influence of different dates of planting on growth, herb, oil yield and quality of essential oil of menthol mint (Mentha arvensis) in the North Indian Plain

A field experiment was conducted for two years (2007-2008 and 2008-2009) to study the effect of different dates of planting for three menthol mint (Mentha arvensis) cultivars (Saksham, Kushal and Kosi; developed by Central Institute of Medicinal and Aromatic Plants, Lucknow, India) on herb yield, oil yield and oil quality. All the cultivars produced higher herb and oil yields when planted on 18 February, compared with cultivars planted on other dates in both years. Average herb yield for Saksham increased by 12.89, 30.66, 54.01 and 85.71%, average herb yield for Kushal increased by 15.09, 30.57, 71.69 and 104.91%, and average herb yield for Kosi increased by 32.48, 53.28, 87.23 and 109.49% when planted on 4 January, 19 January, 3 February and 18 February, respectively, over cultivars planted on 20 December. Among the cultivars, Kosi produced a higher herb yield than Saksham and Kushal planted on 18 February. Saksham, Kushal and Kosi produced similar to 89.39, 152.04 and 170.22% higher oil yield, when planted on 18 February over their respective planting date of 20 December. Maximum menthol content was recorded in cultivar Saksham when planted on 18 February and in Kushal and Kosi when planted on 4 March.