甘藍黑腐病之生物防治研究

Abstract

甘藍黑腐病造成甘藍的減產，一直以來都是難以解決的問題。本研究測試生物防治方法，期能提供目前既有防治選項外的另一可行方案，以減輕黑腐病對甘藍的危害。首先以誘導系統抗性能力為篩選指標，同時搭配甘藍苗生長影響作綜合性評估，得知菌株28-5、AA2-3、37-1與M-2最具應用潛力。以此四個菌株進行田間應用試驗，比較涵蓋甘藍外部與內部病徵之罹病程度，顯示菌株37-1之生物防治效果最佳。在測試各菌株葉面保護能力時，菌株37-1之保護率亦最佳，故針對菌株37-1進行ISR與葉面保護特性之探討，包括菌株37-1之最適施用濃度。在病徵發展方面，根圈施用菌株37-1再接種病原細菌，12天後的罹病度與對照組之差異最為明顯，而葉內病原族群則於接種後7~9天呈現變化；觀察葉緣水孔癒傷葡聚醣累積情形，發現菌株37-1處理的甘藍植株於接種後第5天呈現與對照組不同的變化趨勢，顯示此菌株可經由誘導系統抗性之機制抑制甘藍黑腐病之病徵發展。

Reduced production of cabbages caused by black rot has been a problem difficult to solve. In this study, biocontrol method as an alternative besides the present disease control measures was investigated to reduce the economic loss caused by cabbage black rot. At beginning, induced systemic resistance (ISR) of plants was used as a main screening index of potential biocontrol agents. In combination with the results of seedling growth, strains 28-5, AA2-3, 37-1 and M-2 showed good potentials for application. Field trial with these four strains showed that strain 37-1 had the best biocontrol activity according to the external and internal symptoms. On the other hand, strain 37-1 exhibited superior activity in foliar protection. Thus, the properties of ISR and foliar protection of strain 37-1 were further investigated, including the suitable concentration of application. In the aspect of disease development, disease severity of the plants pre-drenched with strain 37-1 were significantly reduced at 12 days after pathogen inoculation as compared with the control without bacterization. In addition, the pathogen populations in cabbage leaves fluctuated at 7 and 9 days post pathogen inoculation following drench application of strain 37-1. The examination of callose deposition on hydathode areas at leaf margin indicated the seedlings of cabbage drenched with strain 37-1 had defense reaction as compared with the control at 5 days after pathogen inoculation. Thus, drench application of strain 37-1 could suppress symptom development of cabbage black rot by a mechanism of ISR.