In ̄uence of medium solidi®cation and pH value on in vitro propagation of Maranta leuconeura cv. Kerchoviana

Aseptic cultures of Maranta leuconeura were established from shoot tip explants. They were initiated on Murashige and Skoog (MS)-basal medium supplemented with benzyladenine (BA, 5 mg/l) and agar (6 mg/l) (starting medium). Explants were transferred at 6 week intervals until the onset of proliferation (ca. 6 months). Thereafter, four subcultures were made in liquid multiplication medium containing BA (5 mg/1) 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 signi®cant differences among the mean values of most treatments were also obtained. Agar and Gelrite (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 response was more pronounced at 5‡0.5 g/l. A medium pH of 5.7 resulted in the maximum 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, liquid medium is preferred for micropropagation until the third subculture. Thereafter, solid medium should be used to overcome production of vitri®ed shoots and to insure obtaining healthy vigorous plantlets with a higher chlorophyll content. Hardening-off and acclimatization of the plantlets that were produced resulted in numerous plants used for indoor decoration. # 2000 Elsevier Science B.V. All rights reserved.