Micropropagation of mature tree of Citrus limon

Abstract

A protocol for in vitro cloning of mature plants of Citrus limon using nodal shoot segments has been developed. Three to four shoots were induced per axillary meristems on MS medium amended with 9 μM BAP. Repeated transfer of the initial explants for up to six passages on MS medium [having 50% of the original concentrations of NH4NO3 and KNO3, and supplement of 250 mg L (NH4)2SO4] with 0.22 μM BAP yielded crops of shoots. Three to four-fold shoot multiplication rate was achieved by subculturing of shoots. The shoots have been multiplied for more than 48 months without loss of vigour. One hundred percent of the cloned shoots rooted: (i) in vitro on half-strength MS medium+27 μM NAA+0.1% activated charcoal, and (ii) ex vitro on soilrite if pulse-treated with 1.07-2.68 mM NAA. Ninety five percent of rooted plantlets survived hardening and transplanting. Micropropagated plants are under filed trials in states of Rajasthan and Gujarat of India. These have flowered and produced fruits.