Variations in growth and morphological characteristics of Casuarina junghuhniana provenances grown in Thailand

Abstract

Variation in growth, stem form and branching characteristics was assessed in a 48-month-old provenance trial of Casuarina junghuhniana planted in Kanchanaburi, Thailand. The trial compared 28 seed sources from the natural distribution of the species in Indonesia, planted stands from Kenya, Tanzania and Australia and a local commercial hybrid clone of C. junghuhniana × C. equisetifolia. The following characteristics were assessed: height and diameter growth; axis persistence; stem straightness; density, thickness and angle of permanent branches; and length, thickness and stiffness of branchlets. There were significant differences between seed sources in most of the characteristics assessed. Principal component analysis suggested a pattern of geographic variation among natural provenances from Indonesia, with Java, Timor and Wetar forming a group separated from Lombok and most seedlots from Bali. In general seed sources from low altitudes grew faster than those from high altitudes. Natural provenances from Bali and land races from Kenya were very variable in growth rate with some being among the slowest growing and some among the fastest growing. Provenances from Bali also showed considerable variation within its group in stem form and branching habit. Selection of suitable provenances to optimize plantation productivity is feasible.