(44(4):420-429)Studies on Resistance of Crucifers to Clubroot Disease Caused by Plamodiophora brassicae

十字花科蔬菜根瘤病係由Plasmodiophora brassicae（Wononia）所引起，為十字花科蔬菜之重要根部病害，嚴重時會造成植株死亡。病原菌菌量在108 propagules／ml時對十字花科蔬菜之感染可達100％；溫度在22.5°C對根毛感染率及發病指數達到最高。抗病篩選之環境為在溫度為22.5°C及病原菌之菌量濃度定為108 propagules／ml，由日本引進之甘藍(CR30─128及CR30─130）之發病率為3.33％及6.33％，結球白菜（祝勝、石井、野崎70.90）之發病率各為8.1％，10.1％，43.3％，及10％；青花菜（HANAMORI、ATSUMORI、SHIGEMORI）之發病率各為13.2％，12.5％及25.6％。對根瘤病呈強抗病性。Clubroot disease of crucifers, caused by Plasmodiophora brassicaeWoronin, is the most important soil-borne disease on crucifers. The optimal temperature for root hair infection and disease incidence to clubroot are 22.5C. When inoculum density is at 108 propagules/ml, higher disease percentage occurs. The disease incidence of cabbage cultivars: CR 30-128 and CR 30-130 to clubroot are 3.33% and 6.33% separetely. CR APPARE Fl and CR of chinese cabbage are 10.8% and 8.1% respectively. Hanamori, Atsumori and Shigemori of broccoli are 13.2%, 12.5% and 25.6% respectively. They are highly resistant varieties