International Journal of Forestry and Horticulture (IJFH) Volume 3, Issue 3, 2017, PP 9-16 ISSN No. (Online) 2454–9487 DOI: http://dx.doi.org/10.20431/2454-9487.0303002 www.arcjournals.org International Journal of Forestry and Horticulture (IJFH) Page | 9 Wood Anatomical Structures of Tropical Acacias and its Implication to Tree Breeding Arif Nirsatmanto 1* , Sri Sunarti 1 , Harry Praptoyo 2 1 Center for Forest Biotechnology and Tree Improvement, Yogyakarta, Indonesia 2 Faculty of Forestry, Gadjah Mada University, Yogyakarta, Indonesia 1. INTRODUCTION Some species in the genus of Acacia were introduced in tropical regions mostly for supplying raw material for forest industries, such as pulp and paper, sawn timber and wood energy. Indonesia, Malaysia, Vietnam, China, India, Philipines, and Thailand were reported as the countries concern for Acacia plantations in the tropic areas [1]. The establishment of Acacias plantations were practiced either by large scale plantation companies or by smallholder grower. The two largest species of Acacias for plantation in Indonesia are Acacia mangium and Acacia auriculiformis. Although these two Acacias were found growing naturally in Eastern part of Indonesia [2], the Acacia plantation was firstly introduced in 1975’s as a part of national land rehabilitation program [3]. Recently market-oriented has driven the Acacias plantation to be economically feasible for diverse end-product. Current new achievement in wood processing technology have made the Acacias could be potentially improved for varies end-product purposes [4, 5, 6, 7, 8, 9]. In addition, progress of breeding in tree improvement program succeeded to improve the stand productivity of the Acacias and produced new variety of Acacia hybrid, an out crossing between A. mangium and A. auriculiformis [10, 11, 12, 13, 14,15]. Based on these two achievement technologies, recently the chance for the end-product diversification from the Acacias wood becomes more attractive. The knowledge of wood anatomical structure is a fundamental component to support the utilization of wood from a forest tree species. Based on this anatomical structure the uses of wood for suitable end- product could be explored. However, the anatomical structure of wood may potentially change during the process of breeding either due to the process of selection or gene recombination through a mating [16, 17, 18]. Therefore, this study was conducted to observe the wood anatomical structure of four improved Acacias: A. mangium, A. auriculiformis and the two Acacia hybrids which were resulted from tree improvement program in Indonesia. Abstract: Some Acacia species are well domesticated in some regions for supplying raw material for industries. Achievement in wood technology and tree breeding had made the product diversification from the Acacias are becoming more attractive. As a fundamental component, however, the information in wood anatomical structure of the Acacias was still limited. This study is aimed to observe wood anatomical structures of four tropical Acacias obtained from a tree improvement program. The wood samples were collected from three years age of four Acacias: Acacia mangium, Acacia auriculiformis, and their hybrids (A. mangium x A. auriculiformis and A. auriculiformis x A. mangium) planted in Acacia hybrid seed orchard. The wood anatomical structures were observed including some macroscopic and microscopic features. The results showed that wood anatomical structures varied among the four Acacias. Some macroscopic features were similar, while the microscopic were slightly variable. Significant difference (p<0.05) was found in proportion of rays and fiber. All fiber dimensions were significant (p<0.05), except for fiber length. Acacia hybrid showed a specific microscopic feature compared to their pure parent species. The results suggest that the change in genetic behavior through breeding process seemed potentially affected the change in wood anatomical structure of the four Acacias. Keywords: Wood properties, macroscopic features, microscopic features, tree breeding, Acacia hybrid. *Corresponding Author: Arif Nirsatmanto, Center for Forest Biotechnology and Tree Improvement, Yogyakarta, Indonesia, Email ID: arifnirsatmanto@biotifor.or.id