摘要：

Non-fluorescent root-colonizing pseudomonads isolated originally from winter wheat roots readily colonized the roots of other crop plants including spring wheat, winter barley, spring barley, oats, lentils and peas. Winter and spring wheat were most susceptible to the deleterious effects caused by the organisms. The specificity was attributed to a toxin produced in culture rather than differences in root populations of the bacteria. The inhibitory bacteria are capable of growth in a minimal salts medium containing extracts of wheat residues. Coinciding with this growth was production of a toxin similar to that produced in minimal salts-glucose cultures but more toxin or a more potent toxin was produced by cultures in the wheat-residue extract medium. Antibiotic (rifampicin)-resistant mutants of the inhibitory pseudomonads heavily colonized (>10 10g 1 dry residue) crop residues but maximum and sustained populations were dependent on temperature and source of crop residues. Largest populations were observed at low temperatures (5°C) and on residue with low C-to-N ratios. Amendment of soil with ground residue favored larger populations of introduced marked pseudomonads, which in turn led to larger populations on the rhizoplane of winter wheat plants.

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