奈米化資材應用於聖誕紅細菌性葉斑病及柑橘潰瘍病之防治評估

近年來奈米科技廣泛應用於農業，國內外研究指出多種奈米化資材對於抑制植物病原菌及病害防治頗具潛力。本研究針對Xanthomonas屬病原細菌引起之聖誕紅細菌性葉斑病及柑橘潰瘍病透過培養基抑菌試驗及植株溫室試驗評估，開發具潛力的奈米化防治資材。聖誕紅是台灣第二大盆花作物，僅次於蘭花。而細菌性葉斑病是聖誕紅栽培上最棘手的病害之一，好發於營養生長期，病斑易癒合壞疽，嚴重時植株落葉，影響商品價值及聖誕紅生長勢。柑橘在台灣是栽種面積及產量最大的果樹種類，柑橘潰瘍病之病徵在葉片、莖部及果實皆會產生，造成葉片光合作用能力下降，生長勢不佳，果實產量減少、外觀不佳、品質低落等。上述病害目前多使用銅劑及抗生素類藥劑進行防治，然而銅劑及抗生素類藥劑的使用已經面臨抗藥性產生、易引發蟎類、藥害等問題，勢必需要更多的藥劑選擇與現行的藥劑搭配使用。本論文透過培養基抑菌試驗，從12種奈米金屬或金屬氧化物中挑選出抑菌效果良好的奈米二氧化鈦及奈米銀10 nm、奈米銀50 nm進行後續試驗。透過六個不同抗感病性聖誕紅品種進行防治效力評估，其中感病品種之防治成效較佳，可降低病害嚴重度30~40%，控制發病情形在40%以下。中感病品種因原本發病嚴重度較低，處理藥劑後大多沒有顯著差異。二氧化鈦以預防性施用效果較穩定，建議施用濃度為500 ppm，可將濃度調高至1000 ppm以進行治療，但效果因品種而異。奈米銀則可以選擇10 nm/200 ppm或50 nm/200 ppm作為預防，奈米銀50 nm/200 ppm對感病品種四季桃喜也有治療效果，其餘品種治療性施藥需將濃度提升至1000 ppm效果較佳。奈米銀10 nm或50 nm以50 ppm與農藥混用，可以增加鏈土黴素的防治效力。針對柑橘潰瘍病選用感病品種四季檸檬進行實驗，二氧化鈦1000 ppm、奈米銀10 nm/200 ppm或奈米銀50 nm/1000 ppm在預防上能顯著降低病斑數量，防治效果與嘉賜銅相當可以作為輪替用藥的選擇。

關鍵字

柑橘潰瘍病；聖誕紅細菌性葉斑病；奈米二氧化鈦；奈米銀

並列摘要

Nanotechnology plays an important role in agriculture in the last decade. Previous studies indicated that various kinds of nano-formulated materials offer a promising potential for controlling several plant diseases. This study is dedicated to applying nanoparticles in the control of poinsettia bacterial leaf spot and citrus canker. In Taiwan, over 1,200 thousand potted poinsettias have been sold each year. The bacterial leaf spot of poinsettia causes brown spots surrounded by yellow haloes on the leaves. This disease usually occurs in the main vegetative growth period of poinsettias from June to September, and it significantly influences the plant growth and limits the poinsettia production. Citrus is the most widely cultivated fruit tree in Taiwan. The citrus canker attacks the leaves, branches, and fruits and leads to lower quality and less production of the fruits. Both bacterial diseases described above caused by Xanthomonas has become more and more serious in Taiwan, but the control measurements seem to be limited. Frequently applications with copper bactericides and antibiotics have resulted in reduced disease control due to bacterial resistance. Besides, the copper bactericides often lead to chemical injuries and the outbreak of mites. Thus, other potential alternatives should be developed. Novel and effective control strategies are expected to be proposed for poinsettia bacterial leaf spot and citrus canker. The control potential of nano-formulated materials are evaluated through in vitro tests and greenhouse experiments. Titanium dioxide nanoparticle (nTiO2) 500 ppm, silver nanoparticle (nAg) 10 nm/200 ppm and nAg 50 nm/200 ppm are suggested for protecting poinsettias from disease. To suppress the disease in the beginning, nAg 50 nm/200 ppm are suggested. In some cultivars, nAg 50 nm/1000 ppm would reduce the disease severity more consistently. Nanoparticles can be integrated with other commercial pesticides. Adding nAg 10 nm/50 ppm or nAg 50 nm/50 ppm into streptomycin + oxytetracycline reduces the disease severity. nTiO2 1000 ppm, nAg 10 nm/200 ppm and nAg 50 nm/1000 ppm are suggested for controlling citrus canker by protection.