Soil inoculation with Pseudomonas aeruginosa 3MT eliminates the inhibitory effect of 3-chloro- and 4-chlorobenzoate on tomato seed germination

The effects of 3-chloro- and 4-chlorobenzoate (3-CBA, 4-CBA) on the germination of differ ent crop seeds were tested. Brinjal (egg plant) and tomato seeds were highly sensitive to 200 mg l(-1) of either 3-CBA or 4-CBA and showed marked reduction in germination percentage and seedling vigour index. A number of abnormalities were observed in all seedlings at higher concentrations of the chemicals. At 400 mu g ml(-1) germination of tomato seeds was completely inhibited on moist filter paper. A marked reduction in protease activity was observed in germinating tomato seeds treated with these chemicals. Inoculation of 3-CBA- or 4-CBA-treated soil with a chlorobenzoate-degrading Pseudomonas aeruginosa 3mT (1 mu g g(-1) soil) completely protected the tomato seeds and seedlings. The inoculated bacterial strain grew well in the soil utilizing the chlorobenzoates acid developed 1 x 10(9) and 8 x 10(8) cfu g(-1) in 3-CBA- and 4-CBA-treated soil, respectively, as against of 3 x 10(7) cfu g(-1) in the absence of these chlorobenzoates. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.