The Effect of Viral Infection on Essential Oil Content, Chemical Composition and Biomass Yield of Mentha cultivars

Abstract

Mentha species are cultivated as industerial crops mainly in Uttar Pradesh and parts of Punjab for production of essential oil but not commerially cultivated in Gujarat. To promote cultivation of some Mentha species in the region, promising cultivars of Mentha arvensis L. (cv. Himalaya and cv. Kosi) and M. spicata L. (cv. MSS-5) were planted in experimental fields to study their performance in ground conditions. During the initial growth period, some cultivars showed symptoms of virus infection for the first time from the region. The characteristic symptoms of the leaves were foliar rugosty, light yellow mosaic, upward curling and retarded growth. The composition of the essential oils obtained from the aerial parts of three viral infected cultivars of Mentha by hydro-distillation were determined by GC-MS. The amounts of oil in healthy and infected M. arvensis cv. Himalaya (0.46 % and 0.31 %), M. arvensis cv. Kosi (0.69 % and 0.21 %) and M. spicata cv. MSS-5 (0.59 % and 0.46 %) were recorded. Twenty two compounds, constituting 90.1 % to 98.6 % of the oil were identified. Menthol (60.8-68.2 %), d-menthone (13.2-17.3 %), menthone (6.5-7.1 %), limonene (6.1-7.1 %) and p-menth-2-ene (3.0-3.4 %) were main compounds in M. arvensis cultivars. Similarly, healthy and infected Mentha spicata cv. MSS-5 had carvone (53.3 % and 46.7 %) and limonene (26.5 % and 29.7 %) as main compounds. Results showed that the viral disease together with presence of whitefly have caused considerable loss of biomass yield and essential oil in the cultivars of Mentha species but had less affect on major compounds, mainly menthol, limonene, menthone and carvone.