引起黑龙江省大豆根腐病的镰刀菌种类鉴定及致病分析

<正>大豆是黑龙江省四大主要粮食作物之一,种植面积和产量均居全国首位。 大豆根腐病是一种世界性的土传病害[1],主要侵染大豆茎基部至根部,引起根茎腐烂,一般田块减产 10%～30%,重病田块减产达 60%以上,严重时甚至造成绝产[2]。由镰刀菌引起的大豆根腐病是大豆生产上的重要病害 [3]。2017 —2018年,对黑龙江省富裕县、讷河市、五大连池市、北安市、克东县、拜泉县、海伦市、望奎县、林口、牡丹江、尚志、

Identification and pathogenicity of Fusarium species causing soybean root rot in Heilongjiang Province

Soybean root rot disease caused by the genus Fusarium was observed from 30 soybean fields during 2017 and 2018 in 12 counties or cities of Heilongjiang Province. A total of 250 Fusarium isolates were recovered from the root tissues of soybean seedling collected from those fields. Identification of the Fusarium species was performed by examining their morphological features and sequences analysis of internal transcribed spacers (ITS) of rDNA. Six species of Fusarium were identified, with F. oxysporum being the predominant species (72.8%), followed by F. solani (15.6%), F. tricinctum (7.2%), F. equiseti (2.8%), F. brachygibbosum (1.2%) and F. graminearum (0.4%). All Fusarium isolates were highly virulent on soybean (cv. Heinong 69), causing root rot disease symptoms, which were reisolated from diseased plants and identified, fulfilling the Koch’s postulates. The pathogenicity tests for representative strains of the six Fusarium species showed that at 14 days after inoculation by sorghum seeds (4 g) fully colonized by Fusarium, the disease indexes of F. oxysporum (m3-3xu), F. solani (p15-5zhu), F. tricinctum (pz2-2), F. equiseti (dy-mz2-1), F. brachygibbosum (p13-1), and F. graminearum (mx7-2) were 69.05, 42.86,78.57, 45.24, 58.96, and 35.94, respectively. Both conidia cultures and secretions of the six isolates could cause root rot on soybean at 14 days post inoculation. The rot was serious with increased concentration of conidial cultures and secretions. F. solani was the most virulent to soybean with a disease index of 56.2, followed by F. oxysporum (44.8), F. graminearum (39.1), F. equiseti (37.2), F. tricinctum (32.9) and F. brachygibbosum (16.2) at a concentration of 1×10⁸ conidia·mL^-1. The disease indexes of F. solani and F. equiseti were 41.0 and 27.7, respectively at concentration of 1×10⁵ conidia·mL^-1, which showed no significant difference related to the disease index at concentration of 1×10⁸ conidia·mL^-1. As for the virulence of fermentation filtrates, F. solani and F. oxysporum were the most virulent to soybean with the disease indexes of 48.6 and 48.6, respectively, followed by F. equiseti (44.8), F. tricinctum (41), F. graminearum (40.1) and F. brachygibbosum (27.2).