Range-wide provenance variation in growth and morphological characteristics of Casuarina equisetifolia grown in Northern Australia

Variation in 14 growth and morphological characteristics was assessed in a 30-month-old range-wide provenance trial of Casuarina equisetifolia in Weip a, north Queensland, Australia. The trial compared 59 provenances from thro ughout the species' occurrence in four broad regions, i.e. natural occurren ces in Australia/the Pacific, natural occurrences in South-East Asia, intro duced populations in Asia and introduced populations in Africa. The followi ng characteristics were assessed: axis persistence; stem straightness; dens ity, thickness, angle and length of permanent branches; length and thicknes s of deciduous branchlets; stem and foliage damage; flowering and fruiting; and height and diameter growth. There were significant differences between provenances in most of the characteristics assessed. Principal component a nalyses suggested a pattern of geographic variation among provenances from the natural distribution, with provenances in Australia and the Pacific Isl ands forming a separate group from those in South-East Asia. No one provena nce showed superior performance for all the characteristics, suggesting tha t inter-provenance hybridisation may be useful in genetic improvement progr ams. Most provenances from Malaysia and Thailand grew vigorously but lacked stem straightness while some Kenyan seedlots, though inferior in growth, w ere superior in stem form. The wide geographic range and extensive cultivat ion of the species offer great potential for selection of generic material for tree improvement programs. Crown Copyright (C) 2000 Published by Elsevi er Science B.V All rights reserved.