Nanotized kinetin enhances essential oil yield and active constituents of mint via improvement in physiological attributes.

Often mint (Mentha arvensis L.) faces unforeseen limitations, resulting in a low yield and quality of essential oil (EO), especially menthol content necessitating the need to explore the potential of modern technology to overcome this predicament. One of such techniques is the use of nanomaterials. The bulk (un-nanotized) form of PGRs (plant growth regulators) has been considered as a potential tool for crop improvement. Utilizing the top-down approach of nanotization, bulk PGR kinetin was ball-milled to the nano-scale range. A pot experiment was conducted on mint applying bulk- and nano-kinetin through foliar application. The concentrations of spray-treatments included 0 (de-ionized water, control), 10, 20, and 30 μM of bulk-as well as nanotized-kinetin. Both forms of kinetin manifested their patterns in the plant. Treatment N2 (20 μM of nanotized-kinetin) excelled in all other treatments for most of the parameters studied. As compared with De-ionized water-spray control, it resulted in the highest improvement in photosynthetic efficiency, Carbonic anhydrase activity, EO content (46.6 %), EO yield (50.8 %), and density as well as the diameter of PGTs (peltate glandular trichomes). Treatment N2, equalled by treatment B2 (20 μM of bulk-kinetin), maximally improved the menthol yield. The highest content and yield of EO, as a result of N2 application, was attributed to its manifestation in terms of the improved photosynthetic machinery, enzyme activity, and vigour (density and diameter) of PGTs. Since treatment N2 increased the most desirable EO-traits, viz. content and yield of EO along with yield of menthol, it might be recommended for successful production of mint.

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