Factors Affecting Pycnidial Production and Pycnidiospore Germination of Phoma Wasabia, the Causal Agent of Wasabi

在山葵黑心病菌危害山葵之過程中，柄孢子是其重要感染源；而柄孢子則來自於柄子殼。由試驗得知，影響柄子殼產生及柄枹子發芽的營養與環境因子，主要計(1)在測試的培養基中，以PDA產生柄子殼較多；至於營養成分(碳、氮源)方面，碳源可能是影響柄子殼產生或成熟與否的主要原因；(2)溫度以20-28℃較佳；(3)水分潛勢在-1 bar至-10 bars間最佳；(4)酸鹼值雖適應範圍廣，但以pH6.5-7.5 間較佳，(5)光照強度，在時十二小時照光下以150至200μE m-2s- 較適合。

關鍵字

山葵；山葵黑心病菌；柄子殼；營養；環境因子

並列摘要

Pycnidiospores are exudated from pycnidia on infected leaves or petioles of wasabi and may play an important role for secondary infection throughout much of growing seasons. The influence of environmental ‘actors and nutritions on the formation of pycnidia and on the subsequent release of pycnidiospores is directly related to the amount of effective secondary inoculum. In vitro study, the results indicted that PDA medium was the best for production of pycnidia among tested media. Of the carbon sources, starch resulted in the highest linear growth for 7 days incubation and higher germination percentage of pycnidiospores. However, only sorbitol and inulin were the better for pycnidial production among tested carbon sources. Nitrogen sources did not significantly affect the production of pycnidia as compared with control (without nitrogen). In environmental factors, Phoma wasabiae produced pycnidia on PDA medium between 12°C and 32°C with the optimum temperature at 20°C to 28°C. Pycnidiospore germinated well between pH4.5 and pH9.5 with the optimum pH value from 6.5 to 7.5. For water potential tests, the hyphal extension rate of the fungus declined with decreasing water potential over the range -1 to -56 bars. However, pycnidial production and releasing pycnidiospores occurred only at water potential among –1 to –10 bars. After 14 days’ incubation, the optimum light intensity for pycnidia1 production was 150 to 200 μE m-2 s- under a 12 hr day-length cycle and 80 to 100 μE m-2 s- under a 24 hr day-length cycle.

並列關鍵字

nutrient and environmental factors；； Phoma wasabiae ； pycnidia ； wasabi streak

國際替代計量

Factors Affecting Pycnidial Production and Pycnidiospore Germination of Phoma Wasabia, the Causal Agent of Wasabi

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