Modulation of physiological activities, active constituents and essential oil production of Mentha arvensis L. by concomitant application of depolymerised carrageenan, triacontanol and 28-homobrassinolide.

Cornmint (Mentha arvensisL.) constitutes most important source of therapeutic agents used in the alternative systems of medicine. The essential oil of cornmint has wide applications in pharmaceutical, agrochemical and flavoring industries worldwide. This study was conducted to explore the individual as well as combined effect of the best foliar concentrations of gamma-irradiated carrageenan (IC), triacontanol (TRIA) and 28-homobrassinolide (HBR) on growth, yield and quality of cornmint. Foliar application of IC, TRIA and HBR, applied individually on plants, significantly improved the plant attributes studied. However, combined application of these plant growth regulators (PGRs) was more effective compared to their individual application. In comparison to other applied treatments and the control, the combination of three PGRs (80 ppm IC + 10−6M TRIA + 10−7M HBR) proved to be the best for most of the growth, physiological, biochemical and agronomic parameters studied. Combined application of the tested PGRs excelled the control in per plant yield of menthol, menthone and menthyl acetate by 135.9 and 134.1%, 180.0 and 161.1% and by 225.0 and 187.5% at 100 and 120 days after planting, respectively. [ABSTRACT FROM AUTHOR]