New Zealand Journal of Botany abstracts
Genotypic variation of height growth and trunk diameter of Cordyline
australis (Lomandraceae) grown at three locations in New Zealand
Warwick Harris
Landcare Research
P.O. Box 69
Lincoln, New Zealand
Present address: Lincoln Botanical, 16 Aylmers Valley Road, Akaroa,
New Zealand.
Email: wdaharris@clear.net.nz
Ross E. Beever
Stephanie Parkes
Landcare Research
Private Bag 92710
Auckland, New Zealand
Ray Webster
Sue Scheele
Landcare Research
P.O. Box 69
Lincoln, New Zealand
Abstract Height growth was measured for 4 years in uniform
garden environments at Auckland (36°53'S, 174°43'E), Lincoln, Canterbury
(43°38'S, 172°29'E), and Invermay, Otago (45°51'S, 170°23'E)
for 28 populations of Cordyline australis from wild sites covering
12° of latitude. Diameters of trunk bases were measured at the end of
this period. Populations differed significantly in their final heights and
in their growth rates in cool and warm seasons of the year. Generally, northern
populations grew best at the Auckland garden site, especially in the warm
season. Trunks of southern and higher altitudes were thicker and tree-height
to trunk-diameter ratios declined the higher the latitude and altitude of
population origin. Variation of population trunk diameter was related to
phenotypic variation of stem diameter of wild populations. Consideration of
the adaptive significance of these results suggests that more rapid and seasonally
continuous height growth could confer a competitive advantage in warmer northern
environments; in the south, photoperiodic restriction of winter growth could
avoid cold damage. Sturdier trees from higher latitudes or altitudes could
be more resilient to physical damage. Applications of the results to adaptation
of plants to New Zealand environments for conservation and production purposes,
to climate change, and to the health of C. australisare indicated.
Keywords Lomandraceae; Cordyline australis; cabbage
tree; height growth; trunk diameter; genotypic variation; latitudinal variation;
altitudinal variation; seasonal growth; adaptive characters; New Zealand
B02066; Received 10 October 2002; accepted 9 May 2003; Online publication
date 26 November 2003
New Zealand Journal of Botany, 2003, Vol. 41: 637-653
0028-825X/03/4104-0637 $7.00 © The Royal Society of New Zealand
2003
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