Abstract
The relationship between rooting and budding of the cuttings of dormant grape vine, cv. ‘Delaware’ was mainly studied from 1969 to 1972. The results were as follows:
1. Optimum temperature of bottom heat was 21°C or more for rooting of the cuttings in early spring. Further, not only bottom heat but also appropriate warm temperatures to the aerial portion were necessary to get better rooting, because warm air temperatures promoted bud-break of the cuttings.
2. Growing buds on the cuttings promoted rooting, and if the buds were removed at planting, rooting percentages and the number of roots reduced markedly. Auxin treatment applied to the disbudded cuttings failed to produce as many roots as those of the control, but it increased the root number slightly as compared with the disbudded control. It is presumed that unknown substances promotive for rooting of the cuttings may exist in the growing buds and act on rooting synergistically with auxins.
3. Defoliating treatment on the dormant cuttings in the fall showed a little promotion on both rooting and budding. The disbudded cuttings at the leaf fall rooted, but the undisbudded ones did not. All the cuttings in the fall, however, did not produce desirable number of roots even if better rooting percentages were obtained.
4. Among plant growth regulators applied to the cuttings after dormancy, both ABA and NAA appeared to promote rooting but not budding.
