Influence of verticillium wilt resistant and susceptible potato genotypes on populations of antagonistic rhizosphere and rhizoplane bacteria and free nitrogen fixers

Abstract

Verticillium wilt resistant A 66 107-51 and susceptible Russet Burbank potatoes differentially influenced populations of rhizosphere and rhizoplane bacteria. Although differences in total bacteria between the two genotypes were not significantly different, selective differences were evident. These included increases in bacteria antagonistic in vitro toward Verticillium dahliae strain RB 5, and bacteria capable of fixing nitrogen that were more commonly associated with the wilt-resistant potato. Bacteria that were antagonistic to V. dahliae were predominantly Bacillus spp. Other antagonists were species of Pseudomonas, Gluconobacter, Flavobacterium, and Streptomyces. Nitrogen-fixing bacteria were Azotobacter and Azomonas spp. The suppression of Verticillium wilt in Russet Burbank during the growing season following the planting of A 66 107-51 may, in part, be explained by the above findings.