Improving micropropagation of Moringa oleifera: The use of semi-solid medium for rooting and sucrose-free liquid medium combined with temporary ventilation for hardening

Abstract

Moringa oleifera is a multi-purpose tree that is now becoming popular as an economic crop due to increasing discoveries of its nutritional and medicinal properties. The present investigation is aimed at improving the micropropagation of moringa, particularly the acclimatization of plantlets, which is still problematic due to the high mortality observed when the micropropagated plantlets are transferred in the field. Rooting of plantlets was done using a semi-solid medium solidified with 4 g/L agar, which was found to support growth and minimize root injury when the plantlets were taken out of the medium. The rooted plantlets were then subjected to in vitro hardening using a sucrose-free liquid medium combined with temporary ventilation through the uncapping of the culture tubes for 20 min in three consecutive days. This has effectively solved the rapid wilting observed when tissue culture-derived moringa plantlets were transferred into the soil. The improved protocol described in the present paper resulted in a very high survival rate (>98%) and is expected to facilitate micropropagation of M. oleifera on a commercial scale.