An attempt to protect winter wheat against Gaeumannomyces graminis var. tritici by the use of rhizobacteria Pseudomonas fluorescens and Bacillus mycoides.

Pseudomonas fluorescens strains III107 and II21 and Bacillus mycoides strains JC192 and K184, stimulating growth of winter wheat, were chosen for the studies. The bacterial strains inhibited on agar nutrient medium the growth of Gaeumannomyces graminis var. tritici (Ggt)--the pathogenic fungus causing take-all on wheat. Both strains of pseudomonads synthesized relatively high amounts of Fe3+ chelators. The strains of bacilli were characterized by the very fast spreading on agar media. Furthermore, strain II21 was highly cyanogenic, and strain JC192 highly chitinolytic. Bacterization of winter wheat seeds (especially with strains III107 and JC192) significantly reduced the percentage of the plants infested with the pathogen in the 28 day glasshouse pot experiment. In the plot experiment, the winter wheat seeds were inoculated with a mixture of strains III107, II21 and JC192. Due to the bacterization the yield of wheat grain and straw was higher in comparison to the series with Ggt alone by 122% and 75%, respectively, but it amounted only to 45% and 43% of the control series not contaminated with Ggt. The decrease of percentage of wheat ears with weight less than 500 mg from 61% in Ggt-series to 25% in Ggt-bacterized-series, and especially the decrease of percentage of wheat ears with weight less than 200 mg from 43% to 14% additionally indicate the partial protection of the winter wheat against Ggt by the rhizobacteria. In the experimental series not contaminated with Ggt the percentage of these wheat ears fractions did not exceed 3% and 0.5%, respectively.

An attempt to protect winter wheat against Fusarium culmorum by the use of rhizobacteria Pseudomonas fluorescens and Bacillus mycoides.

Inoculation of wheat seeds with two strains of Pseudomonas fluorescens (III107 and II21) and two strains of Bacillus mycoides (JC192 and K184) isolated from winter wheat roots, as well as with one strain of P fluorescens (ID13) isolated from oat roots, reduced the negative influence of Fusarium culmorum on winter wheat in a 28 day pot experiment. The bacterial strains (especially III107 and chitinolytic JC 192) markedly increased the plant seedlings emergence and the plant biomass (the shoots weight up to 252%, and the roots weight up to 229%) in comparison to the experimental series with E culmorum alone. Also in a microplot experiment the yield of grain and straw of winter wheat, inoculated with the bacterial strains (especially JC192 and III107) and growing in soil contaminated with F. culmorum, was higher (the grain yield up to 120%, and the straw yield up to 139%) than in a series with F. culmorum alone (100%). In both experiments the highly cyanogenic strain II21 was least effective. A linear correlation (r = 0.926) and a rank Spearman's correlation (rSp = 0.991), both significant at p<0.01, between the weight of plant biomass in the pot experiment and the yield of whole shoots in the microplot experiment were found. It suggests that the same mechanisms worked in both experiments, although with different intensity.