Histological studies on callus and shoot induction in culture of Trifolium nigrescens Viv. in vitro

The development of callus and adventitious shoots from hypocotyl and cotyledon of Trifolium nigrescens seedlings was studied bjr light microscopy. Calli were formed by multiplication of all living cells of explants except for cotyledonary epidermis within the first week of culture on MS medium (Murashige and Skoog, 1962) supplemented with 0.5 mgl-1 NAA and 2 mgl-1 2iP. All the shoots induced from cotyledon- and hypocotyl-derived calli were of multicellular origin and resulted from meristematic cells at peripheral regions of the callus. Copious changes in starch content accompanying callus formation and shoot initiation indicate its significant role in organogenesis of T. nigrescens.