Influence on mycotal species diversity by different stem parts of submerged aquatic plants that inhibit the growth of aquatic organisms

We investigated the association of particular stem parts of six submerged aquatic plant species belonging to inhibitory plants with the occurrence of aquatic fungi and straminipiles in water bodies of different trophism in Poland. Plant stems were cut and separated into basal, middle, and apical parts, washed, and exposed (in containers) to identical water samples from a river and a pond, respectively. As control, containers with the same water samples remained without plants. A total of 63 fungal species, including 11 Fungi, 2 Protista and 50 Straminipila species were retrieved from all water samples. The lowest number of taxa was recorded in the containers with apical plant parts and the greatest number in containers with middle and basal parts of the plants. The mean ratio of fungi found in water samples with plant fragments versus those without plants ranged for the apical parts from 1.0 to 1.1 (mean 1.1), for middle part from 1.2 to 1.7 (mean 1.5) and for basal parts from 1.7 to 2.3 (mean 1.9). The results indicate that apical stem parts excrete more extracellular products that inhibit the growth of Fungi and Straminipila than the more proximal parts.