دراسة الخصائص المظهرية والمجهرية لأنواع الفطر Fusarium وتأثير الظروف البيئية في نموه وتكاثره
Abstract
A laboratory experiment were achieved to identify 17 isolates belong the genus of Fusarium and to study the effect of environmental requirements e.g. temperature, pH, light and type of growth medium on growth and sporulation of five species of Fusarium.The identification of F. anthophilum, F. babinda, F. beomiformae-A, F. beomiformae-B, F. concentricum, F. denticulatum-A, F. denticulatum-B, F. graminearum, F. nelsonii, F. oxysporum, F. sacchari, F. scirpi, F. solani-A, F. solani-B, F. solani-C, F. sporotrichioides and F. verticillioides were based on morphological and microscopical characteristics.The results of this experiment showed that the growth of F. graminearum was significantly higher than that on F. oxysporum f. sp. lycopersici , F. babinda, F. beomiformae-A and F. nelsonii after the 2nd , 4th and 6th day of incubation. The F. scirpi , F. babinda and F. nelsonii have been recorded for the first time in Iraq. The growth of F. graminearum was fairly fast and covered 100% of petri-dishes in 4th day of incubation at all levels of temperatures (20, 24, 28 and 32Cº), pH (5,6,7, 8 and 9), lighting times. The impact of growth medium was also substantially affected the growth of F. graminearum comparing with other four species as fungi covered the entire area of the dish at fourth day of incubation in PDA, while the rest of the species showed significant differences in growth rates for the duration of incubation. F. babinda and F. nelsonii were covered the area of the dish at the sixth day of incubation in Czapek's and Carrot media respectively , while the growth of fungus F. oxysporum f. sp. lycopersici was the slowest among all the four isolates which not filled the plat at sixth day of incubation. The results of this experiment have shown the variability of growth rate in studied fungi, and demonstrated the adaptation capability of F. graminearum to grow at different growth conditions, compared with other species.
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