ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Cuttings of Agathis australis (D. Don) Lindl passed through a well-defined series of morphological changes prior to root emergence. These phases were incorporated into a morphological index which can be used as a guide for the selection of cuttings at known developmental and anatomical stages. After a variable period (lag phase) during which no external change occurred there was an increase in stem diameter a few milimetres above the cut base. This swelling gradually increased in size and isolated bulges developed. Longitudinal splits then arose in the epidermis over the bulges, followed by root emergence through the splits. Root initiation occurred shortly after the sub-basal swelling commenced in cuttings that eventually rooted. Removal of the basal 8 mm of a rooted cutting (which included the roots) usually led to re-rooting of the cuttings. However, if the roots were merely trimmed off, the cutting never formed new roots and always died. The basal region apparently has the capacity to produce only one set of roots. Occasionally the stem diameter continued to increase and the swelling extended to include the basal region. Such cuttings never formed isolated wellings and never rooted.In general the younger the plant from which the cutting was taken, the shorter the lag phase and the higher the final percentage rooting. Cuttings taken from older plants had a lower rooting percentage and a more variable lag phase, which was related to the time of year the cuttings were taken since root emergence always occurred in spring. Irrespective of the age of the original material there was a constant time period (3–4 weeks) from root initiation to root emergence.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1984.tb06356.x
