IJSRP, Volume 4, Issue 1, January 2014 Edition [ISSN 2250-3153]
U.V.A. Buddhika, G. Seneviratne, C.L. Abayasekara
Beneficial microorganisms used as biofertilizers enhance seed germination and vigour through breaking seed dormancy and hormonal effects. However, their higher production of hormones like indole acetic acid (IAA) result low seed germination. Therefore, they need a regulation of the IAA production for increased plant growth. Such control exists in developed fungal-bacterial biofilms (FBBs), fungal surface-attached bacterial communities. Therefore, present study compares two FBBs and their seven bacterial monoculture counterparts for IAA production and seed germination with maize as the test plant. Results showed that two biofilms increased seed germination and vigour significantly compared to the monocultures whereas, relatively low IAA concentrations, which were comparable with lower limit of the monocultures. IAA production of monocultures was related negatively to seedling vigour, confirming that relatively low IAA concentrations are more favorable for seed germination. Thus, results suggested a regulatory mechanism for optimizing IAA concentration, and/or factors other than IAA for plant growth benefits in the case of biofilms. In conclusion, it is clear that the FBBs differ from bacterial monocultures in regulating improved seed germination and plant growth. Consequently, FBBs warrant formulating biofertilizers in the biofilm mode for futuristic agriculture.