Iron absorption by excised grapevine roots
DOI:
https://doi.org/10.5073/vitis.1980.19.105-112Abstract
Excised roots from cuttings of Vitis vinifera cv. Verduzzo and of two rootstocks V. berlandieri x V. riparia 420 A and V. berlandieri x V. rupestris 1103 P. were tested for iron absorbed from FeEDTA solutions.
Absorption rates decreased with time. At 0-2 °C iron absorption was only 50-60 % inhibited. BPDS, a specific chelator for Fe2+, inhibited almost completely absorption showing that reduction from Fe3+ to Fe2+ was needed both at 30 °C and at 0-2 °C. As pH increased from 5 to 8 absorption rate doubled for the cv. Verduzzo, increased about 5 times for 1103 P. and about 10 times for 420 A.
Also the apparent kinetic constants of absorption were very different in the three grapevines: both Vmax and Km were in the order: 1103 P.> Verduzzo > 420 A. The presence of a conspicuous part of not exchangeable absorption apparently not dependent on metabolism and the possibility of characterizing cultivars and rootstocks as to nutritional requirements through ion absorption measurements are discussed.
Absorption du fer par les racines coupées de la vigne
Des racines coupées de x cv. Verduzzo et des porte-greffes V. berlandieri x V. riparia 420 A et V. berlandieri x V. rupestris 1103 P. ont été étudiées quant au fer absorbé de solutions de FeEDTA. La vitesse d'absorption diminue en fonction du temps. A 0-2 °C l'absorption est inhibée seulement de 50--60 %. Le BPDS, chélant spécifique du Fe2+, inhibe presque complètement l'absorption, ce qui démontre que la réduction Fe3+ -> Fe2+ est nécessaire à 0-2 °C ainsi qu'à 30 °C. Lorsque le pH passe de 5 à 8 la vitesse d'absorption se redouble pour le cv. Verduzzo, elle augmente d'à peu près cinq fois pour le 1103 P. et d'environ dix fois pour le 420 A. Les constantes ciné tiques apparentes de l'absorption sont aussi très différentes pour les trois vignes: Vmax et Km sont toutes les deux de l'ordre de 1103 P. > Verduzzo > 420 A.
On discute la présence d'une part remarquable· de l'absorption qui n'est pas échangeable et qui apparemment ne dépend pas du mé tabolisme, ainsi que la possibilité de caractériser les cultivars et les por te-greffes suivant leurs besoins en substances nutritives minérales au moyen de mesurages de l'absorption des ions.
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