Recent developments in acacia planting: proceedings of an international workshop held in Hanoi, Vietnam, 27-30 October 1997

The 1300 species of the genus Acacia extend around the globe, from Australia through Asia to Africa and the Americas. These nitrogen-fixing trees and shrubs grow in a range of environments and fill an important niche in natural ecosystems. They have also been planted as exotics in over 70 countries for land rehabilitation, shade and shelter, and to produce a range of wood and non-wood products including firewood, charcoal, building poles, tannins and fodder. In recent years extensive plantations have been established in Asia to provide wood pulp for paper and textile manufacture. This book contains 52 papers and 7 short communications on recent developments in planting tropical and subtropical acacias presented at a workshop held in Hanoi, Vietnam, 27-30 October 1997. It brings together the research results and experiences of scientists involved in developing new technologies for acacia planting in Asia and Australia and forest managers facing practical problems growing acacias in the region. Many papers refer to well-known species, such as Acacia auriculiformis, A. mangium and A. mearnsii, but others report the results of testing lesser-known species in a range of environments. The 57 participants at the workshop reviewed the major issues arising from the meeting, identified gaps in knowledge and made recommendations for future research. The key areas were: genetic resources and tree improvement, silviculture and site management, pests and diseases, physiology (including soil symbionts), social, economic and utilisation issues, and mechanisms to foster future collaboration

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

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

Floral Structure and Breeding Systems of Manglietia conifera Dandy (Magnoliaceae)

Manglietia conifera Dandy is a fast-growing tree species that has been introduced to China from Vietnam, which has great potential for commercial planting. However, plantation development is hindered by a lack of seed material, due to low natural seed-set in locally grown trees. Thus, we investigated the morphological characteristics of male and female flower organs, and conducted controlled pollination to understand the breeding systems of the species. The individual flower of M. conifera is bisexual, and the stamen group is polymerized at the base of the receptacle. Pollen is symmetrically distributed on both sides. Controlled pollination suggests that apomixis does not occur in M. conifera. Results from the flower structure, pollen–ovule ratio, outcrossing index, and controlled pollination indicated that the breeding system in M. conifera was outcrossing (partially self-compatible, pollinators required), and self-incompatibility occurred in a later stage of embryonic development. Moreover, the self-incompatibility phenomenon was revealed by the abnormal germination of pollen on the stigma. This paper provides a basis for controlled pollination programs of M. conifera