Recent trends in soil microbiology suggest that certain soil microbes have a positive effect on seedling
growth and development. A study was conducted to investigate the interactive effect of the plantgrowth
promoting fungi Trichoderma harzianum and the arbuscular mycorrhizal fungi (AMF) in growth
and development of tomato (Solanun lycopersicum) seedlings grown under greenhouse conditions. A 3
× 3 factorial experiment was laid out in a completely randomised design with six replications. At harvest
(42 DAP), when compared with the control, T. harzianum and/or AMF treated plants improved shoot
length, root length, dry shoot mass and dry root mass. Pre-inoculation with AMF increased shoot N, P
and S content of tomato seedlings, whereas pre-sowing with T. harzianum alone increased the shoot N.
Generally, shoot Zn and Mn content were affected by both fungi, with the best result observed when
AMF was applied 2 weeks after T. harzianum. The percentage of roots colonised by AMF was less than
15% regardless of the time when T. harzianum was applied. However, the percentage of roots colonised
by T. harzianum was greater than 90% at all times. In conclusion, this study suggested that T.
harzianum and AMF have the potential to improve tomato seedling growth and development.