Effect of zeolite-containing mineral complex on substrate microbiological characteristics during protected cultivation of <i>Rubus fruticosus</i> L. planting material

When growing plants of the genus Rubus in protected cultivation conditions, great importance is attached to the substrate quality, especially its microbiological characteristics, since a favorable environment for pathogen development is created in such conditions. Adding a zeolite-containing mineral complex (ZMC) to the substrate reduces the risk of phytopathogenic infection due to ZMC valuable physical and chemical properties. The study aims to evaluate the effect of a zeolite-containing mineral complex on the substrate microbiota composition when growing blackberry planting material in a winter greenhouse. The biological objects in the experiments were Rubus fruticosus L. plants, as well as isolated microorganisms. The study used common microbiological analysis methods. The assessment of microbial contamination of different fractions (0.001–0.002 mm, 0.5-1.0 mm, and 2.0-4.0 mm) of the studied complex revealed a decrease in the number of colony-forming units (CFU) of bacteria from 5.3×10 6 to 1.5×10 6 with an increase in the granule size. In the study with the smallest particle size, Penicillium spores were detected. This is due to the fact that small granules are more susceptible to contamination with polluted air. Moreover, it was found that in the presence of ZMC, the number of CFU in aqueous suspension of the fungi Fusarium oxysorum Schltdl. and Alternaria alternat а (Fr.) Keissl. decreased by 7 and 8 times, respectively. When the complex under study was added to peat mixture at a concentration of 10, 15, and 20%, the number of fungi CFU was observed to decrease on average by more than 5 times. After cultivating blackberries during the growing season, pathogenic fungi of the genera Cladosporium , Alternaria , Fusarium were found mainly in the substrate without ZMC. Peat mixture with 10% of the investigated complex contained on average 4.5 times less Clad о sporium and Alternaria . Fusarium fungi were not detected. The results of the conducted research can serve as a scientific justification for using ZMC to reduce the infectious load on plants during the cultivation of R. fruticosus planting material in greenhouse conditions.