Micropropagation of woody taxa and plant productivity.
Regeneration of nine woody taxa, i.e. Acacia auriculiformis, A. nilotica, Albizia amara, A. lucida, A. procera, A. richardiana, Leucaena leucocephala, Sesbania macrocarpa and Populus × euramericana [P. canadensis] has been accomplished. The explants were excised from in vitro raised seedlings in the first five species, field-grown as well as juvenile tissues in the next three and 20- to 25-year-old trees in the last taxon (Populus). The axillary buds differentiated multiple shoots in Acacia auriculiformis and A. nilotica on B5 + BA + CW medium. Shoots of the former taxon, after subsequent transfer to B5 + NAA or IAA medium, organised roots. Plantlets developed in hypocotyl explants of all the four species of Albizia through organogenesis. Plants also differentiated via somatic embryogenesis in A. richardiana. In Leucaena leucocephala, plantlets were obtained from cotyledons and axillary buds on B5 + BA medium and from shoot tips of 5-year-old field-grown trees on MS + BA + NAA medium. Both the nodal and internodal segments of Populus differentiated multiple shoots even on MS basal medium. Its excised shoots rooted well on MS + NAA + AC medium. In this species, seasonal variation in morphogenic response of stem explants is very conspicuous. Maximum response (up to 95%) was observed from March to May, which declined gradually and dropped to zero from December to February. In Sesbania macrocarpa, multiple shoots developed from cotyledon, hypocotyl and nodal explants on B5 + BA medium. Such excised shoots organised roots on B5 + IBA. The plantlets were transferred to the field where they flowered and set viable seeds. In addition, leaflet explants of Sesbania also organised 15-20 shoots per explant on B5 + BA + NAA + PVP medium.