銅過量對葡萄扦插苗生長與植體銅濃度的影響

施用含銅制菌劑是葡萄栽培慣用於防治露菌病原（Plasmopara viticola）的植物保護措施，然而長期施用可能使葡萄園土壤的銅累積量升高。由於葡萄植株地上部對銅的毒性作用不敏感，通常不易由植株地上部的形態外觀，察覺初期與輕微的銅毒害，但根部可能已承受銅過量的逆境與毒性作用。本研究以葡萄扦插苗的水耕試驗，模擬葡萄植株根部受土壤溶液中銅過量的影響，藉以探討葡萄植株各部位對銅的毒害反應及其累積性，以期找到適合做為觀察與診斷植株受銅過量影響的毒害指標。本研究以巨峰葡萄（Vitis vinifera L.）的扦插苗，於不含銅的10% Hoagland養液之背景溶液，進行銅添加處理的曝露試驗（0、0.1、1、10、25和50 μM Cu），持續15天的水耕培養後，分別觀察植株外形和根尖組織切片，並測量根伸長量、根和葉的乾重及植體各部位的銅濃度。試驗結果顯示，植株形態在低濃度處理下（0.1和1 μM Cu），與控制組（0 μM Cu）無顯著差異；當植株曝露於高濃度處理下（10-50 μM Cu），根部褐化漸趨嚴重，根伸長量大幅減少，由根尖組織切片觀察發現，部份皮層細胞已產生質壁分離（plasmolysis）的現象，表示扦插苗根部組織已嚴重受損。由葡萄扦插苗的根、莖和葉之銅濃度分佈得知，根的銅累積濃度顯著高於莖和葉；相較其它植物種類，葡萄葉的銅濃度與其它植物相近，葡萄莖的銅濃度則有偏高的趨勢，而葡萄根部的銅濃度明顯高於其它植物，表示葡萄植株有更強的能力將銅累積在根部。由於根部對銅的毒性作用較敏感，且根伸長量和乾重分別與莖和葉的銅濃度有顯著的非線性相關，經由監測現地葡萄地上部莖和葉的銅濃度，將有助於診斷根部對銅過量的初期毒害反應，可避免植株遭受嚴重的逆境傷害。

關鍵字

巨峰葡萄；劑量反應關係；組織切片

並列摘要

Copper-based fungicides have been routinely used for viniculture to prevent downy mildew (Plasmopara viticola). After application of copper-based fungicides for a long term, a significant accumulation of copper (Cu) will be found in surface soils of the vineyards. The early and mild Cu toxic effects can not easily be identified because the aboveground tissues of grapevines are insensitive to excess Cu; nevertheless, Cu rhizotoxicity would resulted in reduction of root growth and damage of root tissues as exposed to excess Cu. In this study, a hydroponic experiment of the rooted grapevine cuttings was carried out to mimic the grapevine plants exposed to Cu in soil solution. The objectives were to investigate Cu phytotoxicity and accumulation in grapevine plants and then to establish toxicity indexes for investigating and diagnosing grapevine plants under excess Cu. Kyoho grapevine (Vitis vinifera L.) cuttings were used in this study. The modified Cu-free Hoagland solution was diluted to 10% strength as the background solution. The treatment solutions of different Cu levels (0, 0.1, 1, 10, 25, and 50 μM) were prepared with Cu spiked in the background solution. The cuttings were exposed to different Cu concentrations for 15 days. At harvest, the plant morphological properties, root apex tissue slice, root elongation, root dry weights, and leaf dry weight were recorded. In addition, the Cu concentrations in roots, stems and leaves were measured. In the results, the cuttings under lower Cu concentrations (i.e. 0.1and 1 μM) grew as well as those under the control condition. As exposed to higher Cu concentrations (i.e. 10-50 μM Cu), the roots were in dark coloration, root elongation was dramatically reduced, and plasmolysis can be observed in the cortex cells in the tissue slice images of the root apex. This revealed that the root tissues of cuttings have been seriously damaged due to Cu toxicity. The distributions of Cu in the roots, stems, and leaves of the cuttings showed that Cu concentration of root was significantly higher than those of stems and leaves. Compared with other plant species, Cu in the grapevine leaves was similar to that in other plants, Cu in the grapevine stems was relatively high, and Cu in grapevine was much higher than that in other plants. Grapevine thus has relatively high ability to accumulate Cu in roots. Furthermore, roots of grapevine cuttings were more sensitive to Cu toxicity than the aboveground parts of plant and root elongation and dry weight were correlated non-linearly with Cu of stems and leaves significantly. Therefore, with monitoring Cu of stems and leaves in situ, one can detect the early rhizotoxicity of grapevine exposed to excess Cu and then prevent grapevine plants from seriously stressed damage.

並列關鍵字

Kyoho grapevine ； Dose-response relationship ； Tissue slice

國際替代計量

銅過量對葡萄扦插苗生長與植體銅濃度的影響

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