生姜枯萎病病原菌的分离鉴定及其接种浓度对生姜枯萎病发生程度的影响

Isolation and identification of ginger Fusarium wilt pathogen and the effect of spore suspension concentration on the extent of disease

从山东平度连作的生姜枯萎病病株中分离得到1株菌株,通过形态学鉴定、rDNA-ITS区序列分析和回接试验确认该菌株为生姜枯萎病病原菌。采用盆栽试验,在健康土壤中接种不同浓度的病原菌孢子悬液研究不同接种浓度对生姜枯萎病发生程度的影响。结果表明:每克土病原菌孢子数量103是导致生姜植株发病的临界浓度,当每克土接种数量不高于105时,病情指数随接种浓度增加而显著增加;当每克土接种数量高于105时,病情指数不再显著增加;随着每克土中接种的病原菌孢子数量的增加,各处理根际土壤中的尖孢镰刀菌数量也增加,且根际土壤中尖孢镰刀菌数量均显著高于土体土壤,根际土壤中尖孢镰刀菌数量是土体土壤的1.19~1.86倍。结论:根际和土体土壤中的尖孢镰刀菌数量共同决定生姜植株是否发生枯萎病,但发病程度的高低受根际土壤中尖孢镰刀菌数量的影响。

A pathogenetic fungus strain was isolated from the diseased ginger in Pingdu, Shandong Province, which was identified as Fusarium oxysporum f. sp. zingiberi by morphological identification, rDNA-ITS sequence analysis and inoculation experiment. Spores of the strain were inoculated into healthy soils in pot at different concentration levels to study the effect of different inoculation spore suspension of pathogen on ginger Fusarium wilt. Resuhs showed a close relationship between the concentration of inocula in soil and the disease incidence rate of ginger Fusarium wilt. The minimal concentration that induced the ginger Fusarium wilt was 103 per gram soil, and the disease incidence increased with the^increase ot：~inocula concentration in soil. Until the inocula concentration attained a certain level（ l05）, the disease incidence would no longer^inereas~. The spore suspension concentration inoculated was found to have a significant influence on the abundance of pathogen in rhizosphere and bulk soil of the ginger plants. The abEndance o~ pathogen in rhizosphere soil was 1.19 to 1. 86 times higher than those in bulk soil in different treatments. It was concluded that wheiher the ginger Fusarium wilt occurred o~＂ not was related to the abundance of pathogen in both rhizosphere and bulk soil, while the disease incidence was mainly determined by the nmnber of the pathogen in plant rhizosphere soil.