Development of the Potential Techniques for Control of Cruciferous Clubroot Disease

• Main Authors: Chien-Yun Cheng, 鄭倩芸
• Other Authors: 黃振文
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/94756437233804627879

碩士 === 國立中興大學 === 植物病理學系所 === 100 === The clubroot disease of cruciferous crops caused by Plasmodiophora brassicae, is one of the most important soilborne diseases. Infected plants typically exhibit abnormal growth, foliar wilting and swollen roots. In Taiwan, the disease was seriously found in Taoyuan, Hsinshu, Taichung and Ilan, causing huge ecomonic losses in agricultural production. For surveying the clubroot disease severity of cabbage plants in the field, it takes long time and heavy work. Therefore, the main purpose of this study is to establish a fast analysis technique for developing and evaluating the control measures of cruciferous clubroot disease in early stage of the crop. In this study, we found the highest infection occurred within 2-4 cm of the main root at the 8th day of inoculation under 24℃ . Besides, examining the infection of 40 root hairs within 2-4 cm region could stand for the whole infection. On the other hand, we also found that relationships among inoculum density, infection, fresh wieght, root wieght and disease severity were highly correlative. By using the fast analysis technique, we screened the antagonistic bacteria and soil amendments for the disease control. The results showed that Bacillus mycoides Wt15 delayed the disease development over two weeks which could reduce 52 % and 47 % of disease severity and clubbed root ratio. Moreover, B. mycoides Wt15 could also increase respectively 5.4 and 2.3 fold of fresh weight and root weight by seed coating method. The observation under the fluorescence microscopy indicated that B. mycoides Wt15 could reduce 21 % viability of resting spores compared with the control and result in shrinking shape of germinated resting spores. The CH100 derivative (250X) was able to reduce 53 % of root hairs infection, however, it did not show the synergistic effect with B. mycoides Wt15 on reducing disease severity.