Removal of senescing Curcuma leaves for essential oil extraction and its effect on rhizome yield.

摘要

Turmeric (Curcuma longa L.) rhizomes, commonly used as spice, are well known for medicinal values in the Indian traditional system of medicine. Essential oil of turmeric is reported to possess antifungal, anti-bacterial and insect repellent activities. The volatile oil from the turmeric leaves has been reported to contain a-phellandrene, 1,8-cineole, p-cymene and a-pinene, arturmerone, turmerone, p-cymene-8-ol, as the major constituents. The turmerones and ar-turmerone have been reported to contain insect repellent properties. The fresh leaf oil of C. longa contains 82.9% monoterpenes whereas fresh rhizome oil has only 16.3% monoterpenes. Monoterpenes in general have been well documented to be active as fumigants, repellents or insecticides toward stored grain insects. The turmeric crop takes 7-9 months for maturity and the rhizomes are harvested in January-February. In north India, the plant shows senescence of leaves with onset of winters and remains dormant during November to January. The present investigation was planned to study the effect of leaf removal on rhizome yield after the plant is exposed to senescence during winters. From uniform plant stand, 0, 25, 50 and 75 percent of leaves were removed, weighed and analysed for essential oil content in end of October or mid November during two consecutive cropping seasons, and the rhizomes were harvested in February. The effect of leaf removal was studied on the total rhizome yield on per plant and per unit area basis along with leaf yield, essential oil content and yield on area basis. It was concluded that without much adverse effect on rhizome yield, turmeric leaves can be harvested at start of senescence to get an additional advantage of leaf essential oil. The chemical composition of leaf oil varied greatly in two accessions studied.