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

Abstract

The production of hydrogen cyanide (HCN) by Pseudomonas putida ATH-1RI/9 and Acidovarax delafieldii ATH2-2RS/1 and its effect on the growth of velvetleaf (Abutilon theophrasti) and corn (Zea 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 velvetleaf shoot length 30–50%. The level of HCN produced in root-free soil by P. putida and A. delafieldii generally increased with higher amounts of supplemental glycine, with P. putida typically generating more HCN (8–38μM) at a given glycine level. However, increased levels of glycine failed to increase HCN in the rhizosphere soil of velvetleaf and corn inoculated with either of the cyanogenic strains. Although HCN levels in soil associated with corn were nearly twice as great as those of velvetleaf, and populations of each bacterial strain recovered from rhizosphere soil of corn were higher than those of velvetleaf, this did not result in reduced corn growth. The growth of velvetleaf as measured by shoot and root growth, however, was significantly inhibited (40–80% of control). The use of cyanogenic bacterial inoculants as a biocontrol of velvetleaf is discussed.