Influence of different substrates on the in vitro rhizogenesis process of early artichoke [Cynara cardunculus L. subsp. scolymus (L.) Hegi]

Micropropagation may represent a useful way to overcome some of the disadvantages of the vegetative propagation of artichoke and promote an effective advance in crop management by the use of selected propagation materia\. However, whereas late cultivars seem to have an easier in vitro adaptability, micropropagation of early cultivars (i.e. cultivars with an autumnal-winter production, the most widespread in our environments) is stili difficult since they show very low multiplication indexes and rooting rate is still unsatisfactory. With the aim at improving the in vitro multiplication technique of these last varieties, the I.S.A.Fo.M. section of Catania began a series of research. In this paper, on the cv. Violet Margot, results on the effects of nine substrates on rooting process are shown. Four substrates were chosen as the most representative of the literature, the other five resulted by the addition to these last of different quantities of B cyclodextrins. Best results as concerns rooted plantlets (62%)and root quality, were obtained by a medium containing NAA (2 mg L-1) and B cyclodextrins (2 g L-1). It seems that these last play a role in the differentiation of a rooting system with several adventitious roots. Genotypical differences may be on the basis of the low response of the studied cultivar to different substrates and may stress the necessity of specific adjustments for each genotype of the medium used for rooting.