Regeneration potential of different explants during micropropagation of neem tree (Azadirachta indica A. Juss.)

Abstract

Azadirachta indica A. Juss., (Neem), a prodigious multipurpose tree, has immense potential to benefit mankind and to protect the environment. In order to investigate the effects of three different explants for its regeneration potential, de-embryonated cotyledon, immature zygotic embryo and nodal segments from a 30 year old neem plus tree were used. Half strength MS medium with benzyl amino purine (3 mg/L) and naphthalene acetic acid (0.5 mg/L) and casein hydrolysate (1 g/L) was effective in shoot bud sprouting from both nodes and cotyledons. Half strength MS medium fortified with TDZ (0.2 mg/L) was effective for induction of somatic embryogenesis from zygotic embryos. Shoot buds initiated from the cotyledons produced a maximum number of shoots per explants (4) which on further sub culturing induced maximum multiple shoots (15) on half strength MS medium fortified with BAP (1.5 mg/L), NAA (0.5 mg/L) and CH (400 g/L) and the nodal explants induced only 4-5 axillary shoots on further sub culturing. Even though immature zygotic embryos produced more number of somatic embryos per explant (25) within a short time (30-45 days), the plantlet conversion was poor (25.52 %). In vitro rooting was observed in half strength MS medium supplemented with IBA (2 mg/L). The regeneration potential of de-embryonated cotyledons through a simple regeneration system may be beneficial for efficient mass propagation of selected plus trees of neem.