Influence of medium solidification and pH value on in vitro propagation ofMaranta leuconeura cv. Kerchoviana

Aseptic cultures of Maranta leuconeura were established from shoot tip expl ants. They were initiated on Murashige and Skoog (MS)-basal medium suppleme nted with benzyladenine (BA, 5 mg/l) and agar (6 mg/l) (starting medium). E xplants were transferred at 6 week intervals until the onset of proliferati on (ca. 6 months). Thereafter, four subcultures were made in liquid multipl ication medium containing BA (5 mg/l) and the produced shoots were cultured in media having different levels of gelling agents and pH. Superior growth and development were obtained in liquid media and significant differences among the mean values of most treatments were also obtained. Agar and Gelri te (gel) used at 5 and 1.5 g/l, respectively, supported the fastest growth and development of both root and shoot. Adding agar plus gel at the rate of 3+1 g/l led to the best growth and development of shoots, but rooting resp onse was more pronounced at 5+0.5 g/l. A medium pH of 5.7 resulted in the m aximum multiplication rate, shoot strength and leaves differentiation. Maranta leuconeura can be successfully micropropagated at pH 5.7 whether in liquid or solid media, but in the solid we recommend the use of gel (1.5 g /l), agar plus gel (3+1 g/l) or agar (5 g/l) in the same order. Also, liqui d medium is preferred for micropropagation until the third subculture. Ther eafter, solid medium should be used to overcome production of vitrified sho ots and to insure obtaining healthy vigorous plantlets with a higher chloro phyll content. Hardening-off and acclimatization of the plantlets that were produced resul ted in numerous plants used for indoor decoration. (C) 2000 Elsevier Scienc e B.V. All rights reserved.