Maximizing Essential Oil Yield and Quality in Menthol Mint (Mentha arvensis L.) by Reducing Water Requirement through Deficit Irrigation Practices

Menthol mint (Mentha arvensis L.) is an aromatic and medicinal plant worldwide cultivated for high-value essential oil.  It comes under angiospermic plant and belongs to family Lamiaceae commonly known as Japanese mint. The high-value essential oil is obtained from the stem and leaf of plant by the process of hydro-distillation through which major ingredient L-menthol is obtained that is used in aroma and pharmaceutical industries. This investigation aimed to reduce water requirements which can enhance its productivity for sustaining menthol mint cultivation in India. The present investigation has been undertaken as treatment combination which includes two varieties viz. i) Kosi and CIM-Kranti; three depths of soil moisture viz. i) 3 cm, ii) 6 cm and iii) 9 cm along with three moisture regimes, i.e., i) 20±5%, ii) 40±5%, and 60±5% available soil moisture (ASM) were tested in split-split plot design during 2018 and 2019 (from February to June). Results from the present study revealed that the maximum oil yield was recorded 116.78 kg ha-1in cv. Kosi and 107.23 kg ha-1 in cv. for CIM-Kranti, whereas menthol yield was recorded 89.23 kg ha-1in cv. Kosi and 85.13 kg ha-1in cv. CIM-Kranti under 6 cm depth of irrigation when applied irrigation at 40±5% available soil moisture (ASM) in menthol mint. However, the lowest water requirement was recorded 118 mm in cv. Kosi and 148 mm in cv. CIM-Kranti. The highest water use efficiency was recorded 0.61 in cv. Kosi and 0.51 kg oil ha-1 mm-1 in cv. CIM- Kranti under 3 cm depth of irrigation and when irrigations were applied at 20±5 % ASM. The highest net returns of $ 1140.91 ha-1 and $ 989.70 ha-1 have been recorded in Kosi and CIM-Kranti, respectively were computed at 6 cm depth of irrigation and when irrigations were applied at 40±5% available soil moisture as compared with other treatments. The irrigation depth (6 cm) applied at 40±5% ASM was found to be a perfect combination for obtaining maximum oil yield, water use efficiency, net returns, and benefit-cost ratio.