The purpose of the studies conducted in the years 1996-1998 was to determine the quantitative and qualitative composition of bacterial and fungal communities in rhizosphere of soybean cultivated in monoculture and non-rhizosphere soil. Besides, the proportion of bacteria and fungi, which were distinguished by their antagonistic effect towards soil-borne pathogens was established. A microbiological analysis of lg of dry weight of soil from rhizosphere of soybean resulted in 3.21 x I ()6 to 8.70 x 106 bacterial colonies and from 70.51 x I 03 to 123.74 x 103 fungal colonies. In the case of non-rhizosphere soil, 3.50 x 106 to 4.75 x 10" bacterial colonies and 16.16 x 10' to 51.38 x 10' fungal colonies were obtained. Besides, soybean cultivation in monoculture had a negative effect on the number of antagonistic isolates of bacteria (Bacillus spp., Pseudomonas spp.) and fungi (Gliocladium spp., Penicillium spp., Trichoderma spp.). Smaller numbers of antagonistic bacteria and fungi in rhizosphere soil of soybean cultivated in monoculture as compared to non-rhizosphere soil, can prove little biological activity, which results in a worse phytosanitaty condition of the soil.

The purpose of the present work was to estimate the effectiveness of grapefruit extract and Pythium oligandrum in protection of common bean, runner bean and pea from soil-borne pathogenic fungi. The investigated preparations were used for seed dressing and spraying plants at the beginning of anthesis. The results pointed out that the applied products considerably improved emergence, healthiness and yielding of the examined plant species. Besides, Biosept 33 SL showed a better effect than Polyversum. Independently on the species, the fewest plants, with the greatest proportion of infected ones and the smallest yield of seeds were obtained from the untreated control. Alternaria alternata, Fusarium spp., Pythium irregulare, Rhizoctonia solani and Sclerotinia sclerotiorum were frequently isolated from infected roots and stem bases as well as from seeds of bean and pea. Fusarium oxysporum tuned out to be dominant. The proportion of the above listed fungi in the treatments with Biosept 33 SL or Polyversum was smaller than in the control. At the same time, the role of those fungi in infecting the plants of common bean, runner bean and pea treated with Biosept 33 SL was only a little smaller than after using Polyversum.

The purpose of the presented studies was to determine the species composition of the fungi occurring on the underground parts of potato at an thesis and to establish the qualitative and quantitative composition ofmicroorganisms living in the soil environment of this plant. Besides, the studies aimed at finding antagonistic microorganisms inhibiting potato infection by soil-borne phytopathogens. The mycological analysis showed that the symptoms of necrosis on the roots and the stem base of potato were caused by Alternaria alternata, Fusarium spp., Colletotrichum coccodes and Rhizoctonia so/ani. The microbiological analysis of the potato rhizosphere gave twice as many bacteria and fungi as from the non-rhizosphere soil. The dominating pathogenic fungi in the examined soil samples were Fusarium spp., A. alternata and R. so/ani. Three times as many antagonistic bacteria Pseudomonas spp. and Bacillus spp. and more than twice as many antagonistic fungi (Penicillium spp., Trichoderma spp., Gliocladium spp.) were obtained from the potato rhizosphere as compared to the non-rhizosphere soil.

The purpose of the studies carried out in the years 1996-1998 was to establish the composition of bacteria and fungi communities in the potato rhizosphere and non-rhizosphere soil. Besides, in the examined samples the studies established the proportion of bacteria and fungi antagonistic towards soilbome pathogens. The microbiological analysis of 1 g of dry weight of soil coming from the rhizosphere of potato revealed from 3.96 x 10' to 7 .26 x 10 6 bacteria colonies and from 51.38 x 103 to 69.96 x 103 fungi colonies. In the case of nonrhizosphere soil of 1 g of dry weight of soil revealed from 3.50 x 10' to 4.75 x 106 bacteria colonies and from 16.16 x 103 to 34.1 0 x 103 fungi colonies. Moreover, potato cultivation had a positive effect on the increase of numbers of antagonistic bacteria (Bacillus spp. and Pseudomonas spp.) and fungi (Gliocladium spp., Penicillium spp., Trichoderma spp.). A larger number of the communities of bacteria and fungi, including antagonistic ones, in the root area of potato, indicates considerable biological activity, which contributes to a better phytosanitary condition of the soil.