BIOLOGICAL ACTIVITY OF FOUR TYPES OF CHITOSAN AGAINST SOME PLANT PATHOGENIC FUNGI

摘要

Chitosan is a natural carbohydrate polymer acquired by deacetylation of chitin, the second most common polysaccharide in nature, has strong biological activity. Antifungal activities of four types of chitosan were determined against plant pathogens of Verticillium dahlia, Alternaria solani, Monilia fructigena, Botrytis cinerea and Rhi-zoctonia solani. Biological activity studies were carried out using the agar plate method with doses 0.2, 0.3, 0.5, 1 and 2 mg/ml of chitosan. Each chitosan type showed strong antifungal activity against test fungi. Mycelial growth inhibition (MGI) rates, Minimum fungicidal Concentration (MFC) and, LD50 and LD90 values of chitosan were calculated. 100 MGI ratios were found in doses of 2 mg/ml for each chitosan. Mycelial growth inhibition was observed even at the lowest dose when compared to the control. According to these results, all doses of chitosan applied against the test fungi were obtained promising results. For the first time with this study, antifungal activity of chitosans was examined against M. fructigena plant pathogen. The result showed that the biological activity of chitosan has been obtained different result according to molecular weight and test fungi. Because of that chitosan is a natural, non-toxic and inexpensive compound, it can be easily used to control plant pathogens.