Sandalwood is an important international commodity recognised for its aromatic oil, which is a key ingredient in many fragrances and cosmetics. Western Australian (WA) sandalwood (Santalum spicatum) is identified as a cheaper, lowerquality alternative to the superior Indian sandalwood (Santalum album). Natural stocks of both S. album and S. spicatum have declined due to historical mismanagement. Subsequently, WA sandalwood has been established in plantations in Western Australia to attempt to meet the demands of the sandalwood industry. Plantation WA sandalwood is promoted as agroforestry, promising economic and environmental benefits. While these benefits are attractive, WA sandalwood has an estimated 25-year rotation. This research aimed to determine the effect of physical and chemical treatments on oil production and heartwood formation in WA sandalwood, aiming to increase oil production, thus reducing the time between establishment and harvesting. The study was conducted over three plantations in the Wheatbelt region of Western Australia: ‘Sandawindy’, ‘Kylie Reserve’ and ‘Brookton’. At each site, four treatments were applied: a dowel soaked with the plant hormone methyl salicylate (MeSA) and inserted into the tree (Treated Dowel), a dowel with noMeSA inserted into the tree (BlankDowel), a drill hole left empty (Empty Drill), and a section of bark removed from the tree (Bark Removed). A group of treeswas left as a control comparison. The Blank Dowel and Empty Drill treatments were established to determine if any significant increases of sandalwood oil in the Treated Dowel treatment were a result of the MeSA, the dowel or drilling into the tree. The Bark Removed treatment was used to mimic drysidedness, a naturally occurring condition common in the rangelands of Western Australia as a result of sun scald. Sandalwood trees were measured and treated in November 2016. Three hundred trees were treated at each plantation, allowing for 60 trees of each treatment at each plantation. Twenty trees for every treatment and control group at each plantation were harvested in November 2017, and all trees were remeasured. Of the approximately 300 trees harvested, 150 were cored using a 12 mm auger drill. These core samples were analysed for oil yield and composition. Total oil was measured and analysed, as well as oil constituents αsantalol, β-santalol, farnesol, nuciferol and β-bisabalol oil compositions (percentage) and yields (%w/w). All harvested trees were cut into eight 25 mm discs, and the percentage of heartwood area at each height was measured. All data were statistically analysed using a univariate general linear model. No treatment consistently increased total oil, or oil component yields, qualities or heartwood area percentages. The presence of MeSA did not have a significant effect on oil production; rather, the physical wounding of the tree had the overall greatest effect. Kylie Reserve showed low oil yield and low heartwood area percentages compared to the other plantations, while simultaneously showing the highest oil yields. This research indicates that a longer period between treatment and harvesting could influence oil production. Further, research extending this study should be conducted to gain more insight into the effect of the treatments on oil production.

中文翻译：

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使用多种处理方法刺激西澳大利亚檀香（Santalum spicatum）油的生产

檀香是一种重要的国际商品，因其芳香油而得到认可，它是许多香水和化妆品的关键成分。西澳大利亚 (WA) 檀香木 (Santalum spicatum) 被认为是优质印度檀香木 (Santalum album) 的廉价、低质量替代品。由于历史管理不善，S.album 和 S.spicatum 的天然存量均有所下降。随后，西澳大利亚州的种植园建立了西澳檀香木，试图满足檀香木行业的需求。种植西澳檀香木被推广为农林业，具有良好的经济和环境效益。虽然这些好处很有吸引力，但西澳檀香木的轮换周期估计为 25 年。本研究旨在确定物理和化学处理对西澳檀香油产量和心材形成的影响，旨在提高油产量，从而减少建立和收获之间的时间。该研究是在西澳大利亚小麦带地区的三个种植园进行的：“Sandawindy”、“Kylie Reserve”和“Brookton”。在每个地点，进行四种处理：用植物激素水杨酸甲酯 (MeSA) 浸泡并插入树中的木钉 (Treated Dowel)，将没有 MeSA 的木钉插入树中 (BlankDowel)，空洞的钻孔 (Empty钻），并从树上取下一段树皮（去除树皮）。留下一组树作为对照比较。建立空白销钉和空钻处理以确定在处理销钉处理中檀香油的任何显着增加是否是 MeSA、销钉或钻入树中的结果。Bark Removed 处理用于模拟干燥，这是西澳大利亚牧场常见的一种因日晒导致的自然状况。檀香树于 2016 年 11 月进行了测量和处理。每个种植园处理了 300 棵树，每个种植园每个处理处理 60 棵树。2017 年 11 月，每个人工林的每个处理组和对照组收获了 20 棵树，并对所有树木进行了重新测量。在收获的大约 300 棵树木中，有 150 棵使用 12 毫米螺旋钻取芯。分析了这些岩心样品的油产量和组成。测量和分析了总油，以及油成分 α 檀香醇、β-檀香醇、法呢醇、nuciferol 和 β-红没药醇油成分（百分比）和产率（%w/w）。将所有收获的树木切成 8 个 25 毫米的圆盘，并测量每个高度的心材面积百分比。使用单变量通用线性模型对所有数据进行统计分析。没有处理持续增加总油量或油成分产量、质量或心材面积百分比。MeSA 的存在对石油生产没有显着影响；相反，树的物理伤害具有最大的整体影响。与其他种植园相比，Kylie Reserve 的油产量和心材面积百分比较低，同时油产量最高。这项研究表明，处理和收获之间的较长时间可能会影响石油产量。此外，应该进行扩展这项研究的研究，以更深入地了解处理对石油生产的影响。