Effect of Azotobacter inoculation on nitrogenase activity of Hordeumvulgare

Abstract

Bacteria with rapid growth on N-free medium and acetylene-reduction activity were isolated from Hordeum vulgare roots collected from pots containing agricultural soils. The isolates were Gram-negative motile rods and were identified as Azotobacter chroococcum. Inoculation of H. vulgareseed or agricultural soil with suspensions of A. chroococcum led to an increase in Azotobacter numbers. Nitrogenase activity was detected on barley roots and increased in response to the inoculation. However, this activity was inhibited when 0.3 or 0.5 % NH 4Cl was added to the agricultural soil.