The species' composition dynamics of mycobiota philloplane and rhizosphere of Fragaria ananassa Duch. under the chitosan solutions' treatment

The study is dedicated to the investigation of the chitosan influence of diverse origin, molecular mass and deacetylation degree on the dynamics of both garden strawberries' phylloplane and rhizosphere aspectual composition. It was defined that Chitosans carry a varied impact on the fungal groups of both Fragaria ananassa phylloplanes' and rhizospheres', as evidenced by the dynamics of their species composition, changes in the population level and occurrence frequency. Namely, the chitosan forms under investigation had a stimulant effect on both micromycetes' and phylloplanes' dominant genus, causing an increase in strawberry leaves' population level after treatment. Nevertheless, the epiphytic fungi species structure of garden strawberry differed 48 hours after treatment with low molecular weight (LMW) and high molecular weight (HMW) chitosan solutions. It has been demonstrated that the rhizosphere mycobiota possesses different sensitivity to LMW and HMW solutions. The greatest inhibitory effect of chitosan forms was observed on penicillium, the soil CFU number of which was less compared to the control one. Thus, the Penicillium sp. amount was 47.4 thousand CFU/g of soil before treatment, becoming 4.9 and 6.3 thousand CFU/g of soil after the low molecular weight chitosan application — 12 and 48 hours after application, accordingly. On the contrary, an increase in abundance in all application variants was observed for the Fusarium genus. This can be explained by the fact that Fusarium genus fungi in the soil are predominantly in the form of mycelium hyphae, being more resistant to chitosan. As a matter of record both incubation time and the environment into which chitosan is put are no less important for its effectiveness except for physiological activity and functional properties, depending on molecular weight.