Growth and Digoxin Content in Digitalis lanata in Controlled Conditions and Natural Environment

Abstract

In two different populations of Digitalis lanata (P7 interbreeding, L3-2A first generation inbreeding), the influence of environmental and genetic factors relative to digoxin production have been studied in controlled conditions and in the field. In controlled conditions (artificial light of 300 µEm^-2s^-1), digoxin content first increased rapidly and then became stable. At the end of the increasing phase, plants had reached the morphologic stage “dense rosette” and digoxin content was maximal. Under weaker natural light conditions (from November to March), the increase of digoxin content progressed more slowly and digoxin was always lower than under controlled conditions (artificial light). In this condition, the “dense rosette” stage was never reached. In field under natural lighting of May to October, a fast increasing phase of digoxin content was observed, but past August-September this content decreased. The influences of lighting intensity, photoperiod, and thermoperiod on digoxin and implications concerning the selection are discussed.