Abstract:
The inhibitory effect of methanolic extract of 100 plant species from 45 plant families were investigated on mycelial growth of Alternaria solani, the cause of early blight of tomatoes, based on paper disc diffusion method. The study was conducted in a completely randomized design with 4 replications. The results showed that methanolic extracts of 21 species exhibited measurable inhibitory effect on mycelial growth of A. solani. The stongest inhibitory effect was obtained for the extracts of Allium hirtifolium and Teucrium chamaedrys with radius inhibitory zones of 19.08 mm ± 0.48 and 15.58 mm ± 0.48, respectively. Furthermore, an experiment was performed to investigate synergistic effect of A. hirtifolium, Ferula assa-foetida and Artemisia sieberi separately and in combinations with each other based on agar dilution method on the growth of A. solani.
Results indicated that a mixture of Allium hirtifolium and F. assa-foetida extracts caused complete mycelial growth inhibition of A. solani. The IC50 and IC95 values for A. hirtifolium bulbs were equal to 78 and 946 ppm, respectively. Moreover, methanolic extract of A. hirtifolium bulb significantly showed the highest inhibitory effect on mycelial growth of A. solani when compared with other plant parts. The results of inhibitory effect of fractions obtained by thin layer chromatography of A. hirtifolium bulbs showed that one band with Rf= 0.41 had an inhibitory effect against A. solani.
