The effect of silver nitrate on micropropagation of Moringa oleifera Lam. an important vegetable crop of tropics with substantial nutritional value

An improved micropropagation protocol facilitating continuous multiplication of elite germplasm of Moringa oleifera has been developed. Initial culture of nodal explant in MS medium supplemented with 2.5 mu M BA resulted in the formation of 12.5 shoots per explant with high frequency of leaf fall (84.3%). To confirm whether the leaf fall is due to accumulation of ethylene in the culture vessel, effect of ethylene releasing agent CEPA in the medium was tested. In order to reduce leaf fall and improve multiplication, varying concentration of anti-ethylene agent, AgNO3 was incorporated in the medium. Addition of 2.5 mu M AgNO3 in combination with 2.5 mu M BA produced maximum number of shoots (17.6) including shoots originated from the base of the explant and shoots from the axillary buds of the primary shoots, where significant reduction in leaf fall (20.6%) was noticed. This enabled sustained multiplication of M. oleifera through continuous subculture without adversely affecting shoot number or shoot quality in terms of shoot length. Microshoots obtained from fourth subculture onwards were used for ex vitro rooting and found that by treating 50 mu M NAA for 30 s, maximum numbers of microshoots (83.3%) were rooted. Rooted plants were acclimatized, survived and were successfully transferred to field. Genetic fidelity analysis using 10 ISSR primers revealed more than 95% monomorphic bands among plants raised in MS medium containing low concentration (2.5 mu M) of AgNO3 and BA (2.5 mu M). The addition of AgNO3 in the medium sustained in vitro growth and effectively prevented leaf fall compared to control, thus demonstrating efficient micropropagation of M. oleifera.