DIVERSITY OF ROOT BACTERIA FROM TOBACCO CROPPING SYSTEMS

Abstract

Abstract Little is known of the effects of various cropping systems on the rhizobacteria associated with tobacco. Our objective was to develop a database on the rhizobacteria present in continuous and rotational fields of tobacco by sampling in field plots over a 4-year period. Plots were established in a Norfolk soil near Florence, SC. For continuous culture plots, tobacco was planted in monoculture for four years. In rotational plots, tobacco, soybean, corn, and tobacco were planted during the 4-year test. Rhizobacteria were isolated from the roots of tobacco and rotation plants and identified by fatty acids composition using gas chromatography (GC/FAME). Arthrobacter and Bacillus were the primary genera recovered from non-rhizosphere soils. Four to seven genera of rhizobacteria accounted for the predominant organisms in both cropping systems; the total number of genera ranged from 17 to 22. Under monoculture tobacco, gram-negative rhizobacteria were dominant in July, whereas, gram-positive root bacteri...