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Anatomical and physiological factors affecting adventitious root formation in Pinus radiata (D.Don) cuttings

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Krstic, MP (1997) Anatomical and physiological factors affecting adventitious root formation in Pinus radiata (D.Don) cuttings. PhD thesis, University of Tasmania.

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Abstract

Pinus radiata is an important plantation forest species in Tasmania and other
regions of the world. The growth of P. radiata from vegetative propagules has been
demonstrated to have many advantages over the conventional seedling method of
propagation. The major problems associated with the vegetative propagation of P.
radiata by cuttings are the seasonal variation in the percentage of cuttings forming
roots and the loss of rooting ability with increased stock plant age. This study
investigated the anatomical and physiological factors affecting adventitious root
formation in P. radiata..
Initial investigations using controlled environment conditions indicated that
anatomical and/or physiological factors rather than the propagation environment were
mainly responsible for the seasonal variation in the percentage of P. radiata cuttings
forming roots. Most of the mortality observed in cuttings occurred prior to callus
formation, highlighting the time of adventitious root development which needed to be
investigated further.
In controlled environmental conditions (20°C, 95% RH, 14 hour
photoperiod), callus initiation was observed approximately 4 weeks after excision and
root initiation was observed at approximately 11 weeks after excision. The
examination of endogenous plant growth regulator concentrations indicated that the
change in the concentration of auxin during the callus formation period may be an
important indicator of rooting success in P. radiata cuttings. In those cuttings which
exhibited a high rooting percentage, a transient increase in auxin concentration was
observed in the basal region of the cuttings 2 and 3 weeks after excision. This was not
observed in cuttings which exhibited a low rooting percentage.
The concentration of carbohydrates in the basal stem region of the cuttings at
the time of excision related poorly to the rooting ability. However, the maintenance of
sucrose concentrations in the basal tissue above approximately 15mg/g DW was
considered important for the successful rooting of cuttings.
The maintenance of adequate water relations in the cuttings during ARF was
demonstrated to influence the rooting percentage. In those cuttings which survived
and rooted, the leaf water potential was maintained above a value of -2.50MPa.
However, in those cuttings which failed to survive the leaf water potential was below
-2.50MPa in the week prior to cutting necrosis.
In summary, the ability of the cutting to react to excision was considered more
important than the absolute levels of these physiological factors at the time of excision.
The physiological basis of these findings is discussed and investigated further, from
which recommendations are made for improved management practices in commercial
P. radiata cutting nurseries.

Item Type: Thesis (PhD)
Keywords: Pinus radiata, Plant cuttings, Pinus radiata
Copyright Holders: The Author
Copyright Information:

Copyright 1997 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1997. Includes bibliographical references

Date Deposited: 19 Dec 2014 02:37
Last Modified: 25 Oct 2016 21:43
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