伽瑪輻射對於進口栽培介質內有害線蟲之滅除效果評估

Efficacy assessment of gamma radiation on plant-associated nematodes

為了滅除進口栽培介質內有害線蟲之存在，準備五種重要植物病原線蟲，包括穿孔線蟲、根瘤線蟲、根腐線蟲、葉芽線蟲、松材線蟲及腐生性線蟲等，測試對於鈷60（^(60)Co）伽馬射線照射的殺死效果。其試驗結果顯示每種測試線蟲對於輻射劑量的耐受性各不相同，而施加高劑量（4至6 kGy）的^(60)Co則可以降低線蟲的繁殖力和提高其死亡率。而在所有測試線蟲中，葉芽線蟲屬對於^(60)Co最敏感，其次是松材線蟲，在暴露於2 kGy後，葉芽線蟲及松材線蟲就能被消滅。而根瘤線蟲和穿孔線蟲則要在4 kGy劑量才能被殺死，因此對輻射具有中等耐受性。另外根腐線蟲和腐生性線蟲則對^(60)Co具有高度耐受性，需要達6 kGy才能殺死。而以幅射照射檢疫處理後之水苔作為蝴蝶蘭大苗之栽培介質，蝴蝶蘭表現出正常的生長及抽穗開花，其試驗結果與對照組比較並無顯著差異，因此試驗結果顯示輻照可能是一種安全且環保的殺死栽培介質中線蟲的方法。

To eliminate unwanted nematodes from import media at the seaport, this study has tested the baseline sensitivity of nematodes to cobalt-60 (^(60)Co) gamma irradiation and its effect on killing nematodes in cultivation media. Five plant pathogenic nematodes including Meloidogyne incognita, Radopholus similis, Pratylenchus coffeae, Bursaphelenchus xylophilus, and Aphelenchoides sp., and one free-living nematode Rhabditis sp. were tested. The results revealed that the tolerance of each test nematode to radiation doses varied. However, the application of high dosages (4 to 6 kGy) of ^(60)Co could reduce nematode fertility and mortality rates. Of all test nematodes, Aphelenchoides sp. was the most susceptible to ^(60)Co, followed by B. xylophilus. Upon exposure to 2 kGy, Aphelenchoides sp. and B. xylophilus were eliminated. Both M. incognita and R. similis were killed by 4 kGy and were moderately tolerant to radiation. P. coffeae and Rhabditis spp. were highly tolerant to ^(60)Co, requiring 6 kGy to kill either species. Phalaenopsis orchids, which were grown in cultivation materials after radiation exhibited normal growth and produced flowers like those grown in untreated materials. Our results indicate that irradiation could be a safe and environmentally friendly method to kill nematodes embedded in a cultivation medium at the seaport.