Effect of accidental factors on rooting of Malus Golden Delicious

Abstract

Summary — In Malus 'Golden Delicious', large fluctuations may occur in rooting from one subculture to another. This may be caused by various accidental external factors. Some of these factors have been examined. However, even though they were varied over a wide range, they had no significant effect on rooting, indicating that they were not the cause of the fluctuations. In the 3 successive subculture cycles examined, the rooting percentage and number of roots showed only small but significant differences. Accuracy in medium preparation had no significant effect, but location in the growth chamber, storage of the medium, and the individual researcher did: medium stored for 6 or 12 wk at 4 °C gave better rooting than fresh medium; one of the 4 researchers always had the best rooting results. This was possibly caused by more careful selection of shoots for rooting.Résumé — Effets de facteurs accidentels sur l'enracinement de Malus Golden Delicious. Chez Malus Golden Delicious, on peut observer des variations importantes dans l'enracinement d'une subculture à une autre. Cela peut être dû à divers facteurs externes accidentels. Nous avons examiné certains de ces facteurs. Mais, malgré une large variation de leur intensité, ils n'ont pas eu d'effet sur l'enracinement ce qui indique que ce ne sont pas eux qui sont à la source de ces variations. Au cours des 3 cycles de subculture que nous avons examinés, le pourcentage d'enracinement et le nombre de racines ont manifesté des différences faibles mais significatives. La précision dans la fabrication des milieux n'a pas d'effet, mais la position dans la chambre de culture, la conservation du milieu et l'opérateur en ont eu. Un milieu conservé 6 ou 12 semaines à 4 °C donne un meilleur enracinement que le même milieu frais. Un des 4 opérateurs a toujours eu de meilleurs résultats. Ceci vient peut-être d'une meilleure sélection des tiges pour l'enracinement.

Factors affecting adventitious root formation in microcuttings of Malus

“…Close to the base, the rooting ability is also lower. In conventional cuttings, this rooting ability gradient has also been observed (Hansen, 1986) (Denissen et al, 1992).…”

“…Figure 1 shows that repeated subculture enhanced the responsiveness to auxin. Poor rooting of microcuttings of many woody crops and the fluctuations in rooting from one subculture to the other (Denissen et al, 1992) may be due to incomplete rejuvenation. Dormancy in buds of plants grown under natural conditions is induced by short day-length or low temperature (Powell, 1987).…”

Effect of inoculation with arbuscular mycorrhizas on rooting, weaning and subsequent growth of micropropagated Malus (L.) Moench

“…Also combining of these two rooting methods was shown to be successful on rooting of apple microcuttings (Zimmerman and Fordham 1985). In rooting of apple microcuttings, there may be large fluctuations due to various accidental external factors (Denissen et al 1992). The timing of harvesting shoots from the subculture medium (De Klerk and Ter , Uosukainen 1992 and the type of carbohydrate used in a gelified rooting medium (Moncousin et al 1992, Uosu-kainen 1992) are crucial.…”