No abstract

Two grapevine clones of two different species of the genus Vitis were cultured in vitro for 14 months without renewal of the culture medium. This long-term storage experiment was in three successive phases: (1) culture of microcuttings at 21 °C for the first month; (2) storage with slow growth at + 12 °C for 11 months; (3) return to 21 °C for 2 months. Shoot and root growth, dry matter content of the plants and uptake of carbohydrates were measured during each phase of culture. Considerable differences in behaviour were observed between the two varieties studied.

Ce travail constitue la première partie d'une thèse de doctorat d'Etat consacrée à l'étude de la croissance de la vigne saine et court-nouée cultivée « in vitro », dont quelques résultats ont été déjà publiés ; nous présentons ici une étude complète de ce problème dans laquelle nous incluons les derniers résultats inédits.Ces recherches sur le court-noué de la vigne ont été entreprises dans le but de mettre au point une méthode de guérison des cépages virosés. Cet objectif a été atteint. Il est possible en effet de guérir par thermothérapie les clones de vigne cultivés « in vitro ». Des plantes saines ont également été obtenues par culture « in vitro » de bourgeons isolés, prélevés sur des plantes malades.Par ailleurs, la culture des organes de la vigne (bourgeons, méristèmes, embryons) en conditions contrôlées a permis d'aborder des études plus théoriques sur la nutrition minérale, l'induction de la rhizogénèse, les relations hôte-virus à différentes températures.

In vitro cultivated plants of Vicia faba minor were propagated by microcutting and used as the initial material for these experiments. Shoot tips were first cultivated on callus-inducing media. The transfer of calluses to media containing lower levels of growth substances resulted, in some instances, in the neoformation of roots and shoots. Rooted plantlets were then obtained from these shoots.Auxins (α-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D)) and cytokinins (6-benzylaminopurine (6-BAP) and 6-furfurylaminopurine (kinetin)) clearly influenced the rate of callus growth and the capacity for organogenesis. They were mixed together to give four callus-inducing media, each containing an auxin (1 mg/L) and a cytokinin (5 mg/L). The media tested for organogenesis contained in each case the same growth substances as the initiation medium but the concentration of auxin and cytokinin was reduced and their ratio modified. Shoot differentiation occurred only when the auxin used was NAA. The most effective combination for shoot formation was the following: 0.1 mg/L NAA and 0.5 mg/L 6-BAP.