Effect of cyanogenic rhizobacteria on the growth of velvetleaf (Abutilon theophrasti) and corn (Zea mays) in autoclaved soil and the influence of supplemental glycine

The production of hydrogen cyanide (HCN) by Pseudomonas putida ATH-1RI/9 an d Acidovorax delafieldii ATH2-2RS/1 and its effect on the growth of velvetl eaf (Abutilon theophrasti) and corn (Zen mays) were tested in the presence of supplemental glycine. In autoclaved soil, varying levels of glycine had no effect on velvetleaf root growth, but did significantly reduce velvetlea f shoot length 30-50%. The level of HCN produced in root-free soil by P. pu tida and A. delafieldii generally increased with higher amounts of suppleme ntal glycine, with P. putida typically generating more HCN (8-38 muM) at a given glycine level. However: increased levels of glycine failed to increas e HCN in the rhizosphere soil of velvetleaf and corn inoculated with either of the cyanogenic strains. Although HCN levels in soil associated with cor n were nearly twice as great as those of velvetleaf, and populations of eac h bacterial strain recovered from rhizosphere soil of corn were higher than those of velvetleaf, this did not result in reduced corn growth. The growt h of velvetleaf as measured by shoot and root growth, however, was signific antly inhibited (40-80% of control). The use of cyanogenic bacterial inocul ants as a biocontrol of velvetleaf is discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.