ブドウ‘デラウェア’の休眠枝ざしの発根に関する研究 (第1報)

Abstract

Activities of plant hormones were investigated with intact vines grown in vineyards or the hardwood cuttings of ‘Delaware’ grapevines during propagation.Monitoring the changes in oxygen uptake through the cutting was not used to determine the time of differentiation of adventitious roots, because an increase in O2 uptake was followed by rooting at the base of the cuttings.Though accelerated ethylene evolution from a whole cutting was corresponding to rooting of the cutting, it was not cleared whether ethylene could be a rooting factor or not.A low level of GA3-like activity was detected in newly bursting buds of grapevine grown in a vineyard, but scarcely in the bursting buds or basal portions of the cuttings during propagation. The relationship between rooting and GA activity in the cuttings was not clear, but such a low level of GA might not affect rooting. This was cofirmed by the result of exogenously applied GA3 to the cuttings.Higher cytokinin activities were detected in growing buds of both intact vines and cuttings by callus culture bioassay. More than three kinds of cytokinin were present and total activities of them had a peak at bud break, but the chromatographic patterns of active substances in the buds of intact vines were different from those of the cuttings. They might not promote directly rooting of the cuttings, but play a role on rooting by promoting bud break.Since auxin activity at the base of the cuttings diminished during propagation, and the activity in the well-rooted cuttings was lower than that in the unrooted cuttings, auxin might have been consumed for root differentiation. Auxin activity in the vine decreased gradually from fall to winter, and increased again in spring.Contrary to auxin, ABA activity in the vine was high in fall, but decreased sharply after leaf fall.These changes in auxin and ABA activities in the vine from fall to spring should be corresponding to difference in rooting ability of the hardwood cuttings. Since exogenously applied ABA had been known to promote rooting of the cuttings, it was very interesting to relate the role and level of this substance, and the quantitative balance with auxin to rooting.