An efficient protocol was developed for in vitro propagation of Abrus precatorius L. through induction of indirect organogenesis in nodal segment derived callus tissue. Yellowish-green nodular callus was induced at the cut surface of the nodal segments cultured on MS fortified with 5.0 mg/l BAP and 0.5 mg/l NAA. The callus differentiated into adventitious shoots when it was subcultured on to MS supplemented with 3.0 mg/l BAP + 0.5 mg/l Kn + 0.5 mg/l NAA. On an average 6.87 ± 0.26 shoots/culture developed. These microshoots were rooted in half-strength MS containing 1.0 mg/l IBA and the rooted plantlets were transferred to soil after proper acclimatization.

Multiple shoots were induced on MS fortified with 2.0 mg/l BAP and 0.2 mg/l NAA within 30 days of culture. Maximum (93%) explants produced multiple shoots with an average 12 shoots per culture after two successive subcultures at 14 days interval in the same medium. Cent per cent rooting was achieved in half strength of MS supplemented with 1.0 mg/l IBA. Following 21 days in vitro rooting period and seven days of ex vitro acclimatization, plantlets were successfully established in natural condition. The survival rate of regenerated plants was 90 per cent.

An efficient regeneration protocol through in vitro direct organogenesis was developed for a valuable medicinal plant Aristolochia tagala Champ. using nodal segments as explants. Multiple shoot buds were induced directly from nodal explants cultured on MS (Murashige and Skoog 1962) basal medium supplemented with 2.0 mg/l BAP (N6-benzylaminopurine) and 0.5 mg/l NAA (a-naphthalenacetic acid). The average number of shoots induced per culture was found to be six. Excised shoot roots were cultured on half -strength MS medium containing 0.5 mg/l IBA. The rooted plantlets were transferred to natural environment after proper acclimatization.

Nodal segments of Stemona tuberosa Lour. were found to proliferated without any differentiation on to MS supplemented with 3.0 mg/l BAP and 0.5 mg/l NAA under continuous dark condition. After 20 days of inoculation under dark condition the cultures were transferred to a daily cycle of 16/8 hrs light/dark photoperiod and there the proliferated nodal segments underwent direct organogenesis producing huge number of shoot buds (25.87/culture). The shoot buds underwent rapid elongation on a range of BAP (0.1 -1.5 mg/l) and IBA (0.1 -1.0 mg/l) supplemented MS. Rooting of elongated shoot buds was successfully achieved (90%) in half strength MS with 1.0 mg/l NAA. The plantlets were finally established in outside environment through a successive phase of acclimatization.

An effective and consistent in vitro propagation technique for Boerhaavia diffusa L. was developed using different types of explants and media compositions. Shoot apex and nodal explants of field grown plants were aseptically cultured on Murashige and Skoog (MS) medium supplemented with different concentrations and combinations of auxins (IAA and NAA) and cytokinins (BAP and Kn). The maximum number of multiple shoot buds (6.65 ± 0.09) obtained from nodal explants on MS medium containing 2.0 mg/l BAP + 0.5 mg/l IAA. Multiple shoot buds underwent rapid elongation (4.24 ± 0.06 cm) on MS media fortified with 3.0 mg/l BAP + 0.5 mg/l NAA. Half strength MS media supplemented with 1.0 mg/l IBA + 0.5 mg/l IAA was better for induction and proliferation (6.42 ± 0.07) of roots and 75% of plantlets were successfully acclimatized to ex vitro condition, exhibiting a normal development. Somatic chromosome number of in vivo and in vitro grown plants were confirmed to be 2n = 26. Chromosome length ranged from 1.40 to 2.43 µm in the mother plants and 1.34 to 2.31 µm for in vitro grown plants. The total form percent (TF%) of mother and in vitro grown plants was 42.91% and 41.16%, respectively. The karyotype formula of in vivo grown plants was 2n = 26 = 4L sm + 6M sm + 2M m + 14S m , whereas that of the in vitro grown plants was 2n = 26 = 8L sm + 4M sm + 2M m + 12S m . The frequency of the chromosome having arm more than 2:1 was 0.08 for in vivo grown plants and 0.15 for in vitro raised plants. Thus, according to Stebbins classification (1971) the karyotype of both plants falls into 2A symmetrical type.