In Vitro Irradiation and Regeneration in Mints

ABSTRACT Regeneration from leaf disks and petioles was studied using orange mint (Mentha citrata Ehrh.), peppermint (Mentha piperita L. cv. Black Mitcham), native spearmint (Mentha spicata L.), and Scotch spearmint (Mentha gracilis Sole cv. Baker). Significantly higher regeneration and lower in vitro contamination rates were observed using petioles of stock plants grown in a controlled environmental chamber or maintained in vitro than using tissue from stock plants in a greenhouse. Regeneration from peppermint petioles was significantly higher on medium containing N6-(2-isopentyl) adenine (2iP) as compared with medium containing benzyladenine or zeatin. Regeneration from y-irradiated mint petioles was inconsistent with doses of 0.27 to 5.4 krad. Microcuttings of mint regener-ants grew significantly taller and produced significantly more roots in Redi-EarthR or a mixture of Redi-EarthR and vermiculite (1:1, v:v) as compared with vermiculite alone.