Free access
Issue
Agronomie
Volume 11, Number 2, 1991
Page(s) 65 - 73
DOI http://dx.doi.org/10.1051/agro:19910201
Agronomie 11 (1991) 65-73
DOI: 10.1051/agro:19910201

État hydrique et mouvements d'eau dans les tubercules d'Helianthus tuberosus L lors de la dormance et de sa levée

R. Sueldoa, b, M. Gendraudb and A. Coudretb

a  Univ nac de Mar Del Plata, ERA-INTA (Balcarce, unidad integrada facultad de ciencias agrarias, CC 276 (7620) Balcarce, Argentina
b  Université Clermont Il, URA CNRS n° 45, laboratoire de phytomorphogenèse, 4 rue Ledru, 63038 Clermont-Ferrand, France

Résumé - L'étude du métabolisme hydrique des tubercules de tompinambour (Helianthus tuberosus L) dormants, placés soit à 24 °C (condition de boulage), soit à 4 °C (condition de levée de dormance) a permis de mettre en évidence le rôle de l'eau dans la dormance et sa levée. Chez les tubercules maintenus à 24 °C, les modifications de la teneur en eau dans les tronçons 2 et 3, au 15e j, pourraient être liées à l'initiation du processus de boulage (30e j). L'augmentation du potentiel osmotique et de la teneur en eau, dans la base des tubercules, permet d'envisager que cette base rend possible l'alimentation en sucres et probablement en eau lors de la croissance tubérisée. Chez les tubercules maintenus à 4 °C, après 9-10 semaines de séjour au froid, d'importantes modifications ont lieu : il y a un afflux d'eau et de matières de réserve vers le bourgeon.


Abstract - Water status and water movements in tubers of Helianthus tuberosus L during dormancy and breaking of dormancy. The study of water parameters in dormant Jerusalem artichokes tubers (Helianthus tuberosus L) kept at 24 °C ("boulage" process) and at 4 °C (to break the dormancy), in darkness showed the role of water during dormancy and the breaking period. During the first 15 d at 24 °C, the water content in the region adjacent to the bud increased (fig 4a), and that in the middle region decreased (fig 3a); this could indicate water movement. The fact that osmotic potential in the basal region increased (fig 2b) and that its water potential was higher than in the middle region (fig 2c) could indicate that the basal region supplied the middle region with sugars and probably with water. The water content increase in the basal region (fig 2a) could explain the increase of osmotic potential in this same region. In tubers kept at breaking conditions of dormancy at 4 °C, during the first weeks the same variations in basal and middle regions were observed. The differences between both treatments (24 °C and 4 °C) were found to be the variation range and the speed at which the variations took place. After these first wk at 4 °C, the decrease in the osmotic potential of the bud (fig 7b) led to an increase in bud water potential (fig 7c); this could indicate water supply by the bud to the adjacent region and explain the increase in turgor pressure of the bud and the water content (fig 7a). It was therefore concluded that after 9-10 wk at 4 °C, significant changes occurred in water status of Helianthus tuberosus L tubers.


Key words: water parameter / breaking of dormancy / tuber / Helianthus tuberosus = Jerusalem artichoke / conservation

Mots clés : paramètre hydrique / eau / levée de dormance / tubercule / Helianthus tuberosus = topinambour / conservation