EFFECT OF AUXINS AND CYTOKININS ON EFFICIENT PLANT-REGENERATION AND MULTIPLE-SHOOT FORMATION FROM COTYLEDONS AND COTYLEDONARY-NODE EXPLANTSOF GROUNDNUT (ARACHIS-HYPOGAEA L.) BY IN-VITRO CULTURE TECHNOLOGY

Tissue cultures were established from cotyledon and cotyledonary-node segments of Arachis hypogaea L. on Murashige and Skoog (MS) medium sup plemented with different concentrations of auxins (IAA, NAA, IBA, and 2, 4-D) and cytokinins (KIN and BAP). For callus initiation, high conc entration of auxins and low concentration of cytokinins were used, whe reas high concentration of cytokinins and low concentration of auxins were used for shoot-bud differentiation. Callus induction and shoot-bu d regeneration frequency, however, varied with genotype, explant, and the different plant-growth regulators combination in the medium. The s hoot-bud multiplication was also influenced by genotype, explant type, and growth regulators. The combination of BAP and NAA produced more s hoots than other combinations. The maximum number of shoots was obtain ed from cotyledonary-node segments on a medium containing BAP (5.0 mg/ L) and IBA (1.0 mg/L). Rooting of regenerated shoots was achieved on a medium augmented with NAA or IBA (2.0 mg/L) in combination with KIN ( 0.5 mg/L). Rooted plantlets were successfully established in the soil, where 95% of them survived.