PLANTES, PENDANT LA VARIATION DE PHOTOPERIODE THE SE

Etude du contenu en sucres de l'épinard (Spinacia oleracea L. cv. Nobel) et d'autres plantes, pendant la variation de photopériode DEGLI AGOSTI, Robert The long-day plant spinach (Spinacia oleracea cv. Nobel) remains vegetative in short-days (SD) of 8 hours of light (8:16 L:D). With 4-weeks old vegetative plants, the photosynthetic activity directly controls the total sugar content in the primary leaves and petioles. When the plants are transferred to continuous light (photo periodic transfer in LL), the total sugar content is sharply increased 2 to 3 hours after the beginning of the photoperiodic transfer. Glucose, fructose and sucrose are the main soluble sugars present in spinach leaves and petioles as indicated by TLC and HPLC techniques. During the photoperiodic transfer the glucose and fructose content increases 5 to 8 fold in the leaves and petioles by comparison with the content at the end of the light period during SDs. The sucrose content is also increased during photoperiodic transfer, but to a lesser extent. This phenomenon is called the "glucose effect" and is also observed in some other photoperiodic plants such as the long-day plants Coleus (Coleus blumei Benth.) and mustard (Sinapis alba L.), and the short-day plant Chenopodium rubrum (ecotype 184). In SD [...] DEGLI AGOSTI, Robert. Etude du contenu en sucres de l'épinard (Spinacia oleracea L. cv. Nobel) et d'autres plantes, pendant la variation de photopériode. Thèse de doctora