TREATMENT OF RYE (SECALE-CEREALE L) SEEDLINGS WITH GROWTH-PROMOTING PSEUDOMONAS STRAINS - PLANT-GROWTH RESPONSES AND SURVIVAL OF BACTERIA IN THE RHIZOSPHERE

From the rhizosphere of rye plants grown in a field, fluorescent Pseud omonas and deleterious for plant growth Fusarium strains were isolated . Pseudomonas isolates synthesized catechol siderophores (No. 6 and 8) , hydroxamate siderophores (No. 44 and 46) or both kinds of ligands (N o. 45 and 26). Bacteria inhibited growth of fusaria in vitro through s iderophoremediated competition for iron. All Pseudomonas strains were good root colonizers. In pot experiments carried out in nonsterile loe ss soil significant increase of plant dry weight was achieved after in oculation with Pseudomonas isolates. Seedlings co-inoculated with dele terious fusaria and pseudomonads had much higher dry weight than the p lants treated only with fungal strains. The biggest plant growth stimu lation was obtained when seedlings were simultaneously inoculated with mixed culture of pseudomonads and Fusarium strain. The plant reaction to co-inoculation depended on Fusarium strain and conditions of seedl ings growth.