Unavailability of a suitable carrier seriously hampered the mass production of bio-inoculant in developing countries including Pakistan. The present study was designed to evaluate the quality of formulated carriers for bio-inoculant on maize. Complete randomized design was applied with six treatments in triplicates. Formulated carriers; FC-1 (40% clay soil + 35% fly-ash + 15% press-mud + 10% lignitic coal), FC-2 (40% clay soil + 40% fly-ash + 10% press-mud + 10% lignitic coal), FC-3 (40% clay soil + 35% fly-ash + 10% press-mud + 15% lignitic coal), FC-4 (40% clay soil + 30% fly-ash + 15% press-mud + 15% lignitic coal) and BC (biozote carrier) were inoculated with broth culture of pre-isolated PGPR strains (MR8 & MR5). Un-inoculated seeds were used as control. Results revealed that all the inoculated carriers showed a significant increase over un-inoculated control related to different growth parameters but FC-4 found better followed by FC-1. The two PGPR strains demonstrated significant variation for shoot height and root length. Interaction effect (inoculated carriers × bacterial strains) remained non-significant in shoot and root. Nutrient uptake by maize plant differed significantly from control due to PGPR inoculated carriers. The highest uptake was observed with FC-4 followed by FC-1. Interaction effect (inoculated carriers × bacterial strains) was significant for N, P, K, Na, Zn, Cu and Mn uptake. Significantly higher nutrient uptake was calculated in plants inoculated with MR8 compared to MR5. Formulated carrier-4 can be utilized for biofertilizer production but further testing on other bacterial strains and crops is recommended.
