Abstract

Verticillium dahliae is a fungal plant pathogen that attacks a wide range of plants including anise causing a wilt disease. The pathogen grows slowly on anise seeds using the standard moist blotter (SMB) or deep-freezing blotter (DFB) methods. In these methods saprophytes and fast growing fungi impair the detection of such slow growing fungi. An attempt was carried out to overcome this problem on anise seeds by applying alkaline seed-bed (ASB) technique for detecting slow growing seed-borne fungi. Data showed significant increase in the incidence levels of V. dahliae (3.4 and 4.73%) when alkaline KOH or NaOH technique was applied as compared to 0.2 and 0.7%, in SBM and DFB methods, respectively. Moreover, the ASB technique proved to be an effective option for early detecting the pathogen on anise seeds after 4 days of incubation in compared to other methods. The in vitro study indicated that the alkaline pH is the favored condition by the fungus. However, V. dahliae was able to grow in a wide range of pH (3.5 to 12.5) with a pH optimum of 8 at which the highest growth rate was recorded (0.96 g.L^-1/day). The maximum glucose coefficient was achieved at pH 8, while the highest glucose utilization was recorded at pH 12.5. These results suggest that ASB technique is recommended for the detection of the alkalophilic V. dahliae.

Key words: Alkaline seed-bed, Pimpinella anisum, seed health, Slow growing fungi,Verticillium wilt.