Sur la variabilité de la capacité rhizogène d'explantats racinaires de Cichorium intybus (var. Witloof) cultivés in vitro : influence de la dimension des explantats initiaux et de la durée de conservation des racines au froid

Abstract

On Cichorium intybus root explants of different size, it is possible to demonstrate the existence of a relation between the volume/surface ratio and adventitious root formation capacities. With a volume/surface ratio equal to one, the highest number of adventitious roots and percentage of explants able to produce roots have been observed. When this ratio deviates from unity, adventitious root formation declines. Cold storage of chicory roots causes breakdown of fructosans and accumulation of sucrose, glucose, and fructose. At the same time, adventitious root formation on explants cultured in vitro decreases. Inclusion of glucose in culture media increases adventitious root production whatever the duration of chicory root cold storage may have been. Results are discussed and the hypothesis of a regulation of adventitious roots by sucrose and reducing sugars is advanced.