RESPONSE OF GIBBERELLIC ACID ON GROWTH BEHAVIOUR AND MENTHOL OIL YIELD OF MENTHA (Mentha piperita L.)

Field studies were conducted in Uttar Pradesh, India, in 2011, to investigate response of gibberellic acid (GA3) on the growth behaviour and menthol content in Mentha piperita under the influences of variable seasons (winter and summer). Uniform suckers of M. piperita were grown in nursery beds with appropriate supply of organic manures. Four weeks old nursery grown saplings were transplanted in pots. All pots were treated by the exogenous application of different successive concentrations (0, 10, 15, 25, 50 and 100 ppm) of GA3. At 75 days after GA3 application in each season (winter and summer), observations on plant height, number of stolons and leaves per plant, leaf area, plant biomass and menthol content were recorded. Results showed that the long photoperiod treatment along with higher concentrations of GA3 favoured more stimulation of menthol content in the peltate glandular trichomes of the M. piperita plant body.