Correlations of Anatomical and Chemical Leaf Characteristics of Eucalyptus Clones with Spontaneous Leaf Spot Disease Severity Associated with Phaeophleospora Fungi

桉樹營養系的解剖及化學特徵與Phaeophleospora spp.真菌所引起的自發性葉斑病嚴重程度的關係

Sri Rahayu ； Ifert Ehrlick Tudon ； Eko Bhakti Hardiyanto

《台灣林業科學》 35卷3期 (2020/09) Pp. 239-249

https://doi.org/10.7075/TJFS.202009_35(3).0004

摘要

Recently, leaf spot disease caused by Phaeophleospora spp. fungi has become a severe problem in eucalyptus clonal plantations. These pathogens can kill Eucalyptus trees, and cases can be found in different stages of tree development, ranging from seedlings in nurseries to trees in the field. Before deploying a large-scale Eucalyptus clonal plantation, selecting clones resistance to disease is important in addition to selecting for optimal growth and wood properties. In this research, we explored anatomical and chemical leaf characteristics associated with potential leaf spot disease resistance. The study was conducted on a 6-mo-old eucalypt clonal plantation at a forestry company in South Sumatra, Indonesia. Three selected clones, i.e., clones 79 and 80 (E. pellita × E. brassiana), and clone 47 (pure E. pellita), were assessed for their growth, severity of spontaneously occurring disease, and leaf characteristics (the stomatal density, stomatal size, thickness of adaxial and abaxial palisade mesophyll, and phenol contents). Clone 79 was susceptible, while clones 47 and 80 were more resistant to the disease. The stomatal size and density and leaf phenol contents assessed from healthy clones were not good indicators for determining resistant clones. The thickness of the abaxial palisade parenchyma, however, was negatively correlated with disease severity. Comparing palisade mesophyll thickness is suggested to be a quick, simple, and cheap approach for a preliminary assessment of potential resistance against leaf spot disease among different Eucalyptus clones.

關鍵字

Clonal forestry ； leaf disease ； palisade mesophyll ； Eucalyptus pellita ； Eucalyptus brassiana

並列摘要

近年來，Phaeophleospora spp.真菌所引起的葉斑病已對桉樹（Eucalyptus）營養系人工林地造成嚴重影響。從苗圃內的苗木到野外的樹木，均可見到病原菌造成不同生長時期桉樹死亡的案例。在進行大規模的桉樹造林前，除了考量生長和木材性質良好的性狀外，篩選具抗病性的營養系也顯得相當重要。本研究中，我們探討了與潛在葉斑病抗性相關的葉片解剖和化學特徵。該研究是在印度尼西亞南蘇門答臘的一家林業公司之6個月大桉樹營養系人工林中進行。針對挑選的3個營養系，即營養系79、80（E.pellita × E. brassiana）、和47（E. pellita），分析它們的生長，發病嚴重程度和葉片特徵（氣孔密度、氣孔大小、近軸和遠軸端柵狀葉肉厚度以及酚含量）。營養系79呈現感病，而營養系47和80則呈現較高抗病性。健康營養系的氣孔大小，密度和葉酚含量，並不是評估營養系抗病性的良好指標。然而，遠軸端柵狀葉肉的厚度與染病的嚴重程度呈負相關。比較柵狀葉肉厚度可做為初步評估不同桉樹營養系對葉斑病潛在抗性一種快速、簡單且便宜的方法。

並列關鍵字

營養系林業 ； 葉病 ； 葉柵葉肉 ； 粗皮桉 ； 吉桉