Stimulation of the Growth of Tomato, Pepper and Mung Bean Plants by the Plant Growth- Promoting BacteriumEnterobacter cloacaeCAL3

The effect of a plant growth-promoting bacterium (PGPB), Enterobacter cloacae CAL3, on the growth of tomato, pepper and mung bean plants was evaluated. Seedlings were grown on vermiculite and supplied with Murashige and Skoog nutrient solutions. In parallel the plants were also inoculated with bacterial suspension. The present study highlights the potential for stimulating growth of plants by application of plant growth-promoting bacteria of the genus Enterobacter. It emphasizes that this bacterium can influence plant growth even in the presence of a nutrient solution. Mineral analysis of the bacterial suspension indicated it contained only trace amounts of minerals and thus rules out the possibility that minerals associated with the bacterium were the cause of the growth promotion effect. Tomato seedlings were more responsive to treatment with E. cloacae CAL3 than were mung bean plants. This was manifested in the shorter time it took to discern the promotion effect in tomato plants and in pepper than in mung bean plants. The promotion effect required the presence of a live bacterium, although a low level of growth promotion was also observed when plants were treated with autoclaved bacteria. These findings suggest that plants may be grown with lower amounts of applied fertilizers and implies (1) a reduction in the cost associated with growing plants and (2) a reduction in the pollution associated with agricultural practices.