Abstracts Category : Other

Growth physiology and productivity of cultivated Aquilaria crassna Pierre ex Lecomte (Thymelaeaceae) in tropical Australia and its reproduction biology

by Sampson Arlene Lpez

Agarwood is a highly prized, resin-infused fragrant wood that has been used since early history in both secular and religious practices. Agarwood is produced mainly by species of the genus Aquilaria. The high demand for agarwood has resulted in overharvesting of the natural population. Growing Aquilaria in plantations seems a sensible approach to supply the market and meet consumer demands. Several initiatives, including the establishment of plantations, are in place in the countries of origin of the species to supply cultivated agarwood. In tropical Australia, a research plantation of Aquilaria species was established to determine the biological and commercial viability of production in an area beyond its natural range. Research was conducted in this plantation as part of this dissertation to improve our understanding of floral biology and the breeding system of Aquilaria crassna, morphological characters that differentiate species of Aquilaria, the environmental, physiological and leaf- morphological characters that influence tree growth and productivity. This knowledge (theoretical and practical) can inform methods, techniques and tools for its cultivation.In this study, analysis of leaf outlines using elliptical Fourier descriptors was used successfully to distinguish morphological variability and discriminate between three species of Aquilaria. Flower anthesis of Aquilaria crassna occurred at evening and early morning, flowers stay open up to 3.5 days. Stigma is receptive when flowers are fully open for one day. Hand-pollination experiments showed that A. crassna is self-compatible and that there is no pollen limitation for fruit production in its new environment. Hybrids between A. crasnna and A. baillonii were possible.Physiological and morphological leaf-traits were a useful predictor of tree productivity. Isotopic composition of carbon (C) in leaf dry matter explained 35% of the variability in diameter. Predictors that explain growth in Aquilaria are C, N, petiole length, number of new leaves produced per week and specific leaf area. CO assimilation increased linearly with PFD peaking at PFD of 1000 mol m s (A(max)). Relative leaf chlorophyll content (determined using a SPAD meter and expressed as leaf greenness) correlated positively with the rate of CO assimilation and % of leaf nitrogen. Leaf greenness index could be used by Aquilaria growers to maximize productivity in Aquilaria. This study provides the evidence that support the cultivation of Aquilaria spp. outside its range of distribution.