The aim of the study was to develop a protocol for in vitro shoot regeneration based on a solid Murashige and Skoog (MS) basal medium supplemented with various concentrations of plant growth regulators (PGRs) like Indole-3-butyric acid (IBA), kinetin (KIN) or benzylaminopurine (BAP) using leaf, petiole, root, and crown disk segments of a valuable medicinal plant Viola odorata. The best percentage of direct shoot regeneration (67.50%) and the maximum number of micro-shoots (9.50) were obtained with crown explants on MS medium containing IBA (0.5 mg A l ). The best elongation (5.25 cm) of micro-shoots was observed in crown explants on a medium containing 1 mg A l !1 gibberellic acid (GA3) followed by GA3 at 0.5 mg A l !1 and similar explants. Irrespective of the concentrations of GA3, the minimum length of shoots was observed in leaf explants. A half-strength MS medium containing activated charcoal and supplemented with 1.5 mg A l !1 IBA resulted in the best rooting (78%) of elongated shoots. All acclimatized plantlets survived and showed a normal growth.The study reports a simple and applicable protocol for micropropagation of V. odorata through direct organogenesis.

Valeriana officinalis, commonly known as valerian, is native to Europe and Asia and has economic importance as a medicinal plant. The effects of auxins (2,4-D and NAA) on callus induction were studied in vitro using basal piece of leaf + petiole (L1) and middle piece of leaf (L2) ). The results revealed that the effect of explant type on callogenesis was also significant. In contrast to KIN or TDZ, addition of IBA to BAP showed positive synergistic effect for plant regeneration and shoot number per callus.

Pomegranate seeds were exposed to electron and gamma irradiations at doses of 5, 10, 15 and 20 kGy to study the relationships between their condensed tannin, NDF, ADF contents, in vitro rumen methane production and protozoa population. Data were analyzed by using the GLM procedure. Orthogonal contrast showed that gamma irradiation significantly increased the NDF content of pomegranate seed as compared to control (P<0.05), however electron beam irradiation did not significantly affect NDF%. The condensed tannin content of the pomegranate seed was significantly decreased by gamma and electron beam irradiation compared to control (P<0.05). Our results showed that there was a negative correlation between the methane production and NDF content of the gamma irradiated pomegranate seed. This means that the methane production of the gamma irradiated pomegranate seed decreased with increasing NDF%. Therefore, it seems that, in addition to tannin, the reduction of the methane production was affected by the cell wall content. Generally, the cell wall content may be more important than tannins in limiting microbial and in vitro fermentation.

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