Seasonal Changes in Auxin Effect on Rooting of Douglas‐Fir Stem Cuttings as Related to Bud Activity

Abstract

The relation of seasonal bud activity to the periodicity of rooting in Douglas‐fir, Pseudotsuga menziesii (Mirb.) Franco, stem cuttings was studied in combination with auxin and cold storage treatments. Cuttings were collected in all months except April and May, for 3 years. Rooting was least in September and October when bud dormancy was most pronounced, greatest in December and January if exogenous auxin was applied, or in February and March if no auxin was used. The buds contributed significantly to rooting from January to April, and were responsible for differences in rooting of terminal and lateral cuttings during this period. Auxin did not enhance rooting in September and October, but at other times it replaced or supplemented the role of vegetative buds in promoting rooting. Auxin also removed the differences in rooting between lateral and terminal cuttings. Cold treatment in October and November removed bud dormancy and enhanced rooting. After November the need for auxin or cold treatment diminished and rooting without either treatment reached a maximum in February and March. Auxin did not change the seasonal pattern of rooting but broadened and enhanced the rooting response in favor of earliness. These results are discussed in relation to the effect of bud activity on auxin response and root initiation. The hypotheses are proposed that cambial dormancy or auxin deficiency is not the limiting factor during bud dormancy, and that cold treatments have the effect of bringing inhibitors and promoters into proper balance for optimum rooting response.

Seasonal Changes in the Effects of Auxin on Rooting in Stem Cuttings of Ficus infectoria

“…Nanda and Anand (1970) observed that in Populus nigra stem cuttings a given concentration of auxin may stimulate rooting in one season and inhibit it in another. Similar observations have been made in Douglas fir by Roberts and Fuchigami (1973).…”

“…This seasonal variation in rooting and in the effectivity of auxins has been attributed to changes in the bud activity (Roberts andFuchigami 1973, Roberts et al 1974) to endogenous levels of auxin contents (Vieitez andPena 1968, Smith andWareing 1972a,b) and to the content of hydrolyzing enzymes and starch (Nanda and Anand 1970) in the stem cuttings. The data presented in this paper suggest that this variation is related to the status of cambial activity in the cuttings.…”

Rooting sitka spruce from southeast Alaska.

“…Both the dilute soak and the quick dip IBA treatments gave better rooting results than the control. In Douglas-fir cuttings, noticeable differences in rooting were noted when IBA treatment was applied to twigs of different branch orders (Roberts and Fuchigami 1973). A direct comparison of the present study's 5000 p/m IBA treatment with published reports in which different concentrations of IBA were used is difficult because the control cuttings of the present study rooted better than the best hormone treatments reported in the literature.…”

Seasonal changes in adventitious root formation in hypocotyl cuttings of Pinus sylvestris: Influence of Photoperiod during stock plant growth and of indolebutyric acid treatment of cuttings

“…In the northern hemisphere propagation of coniferous plants by cuttings is usually only possible when cuttings are collected from late fall until bud-break the following spring. The length of this period may vary from year to year (Roberts and Fuchigami 1973) and may differ between species (Thimann and Delisle 1942). For some Pinus species, e.g.…”