Co-inoculation with the root endophytic fungus Piriformospora indica and endophytic bacteria improves growth of solanaceous vegetable seedlings

ABSTRACT Application of beneficial rhizobacteria may improve the growth of vegetable transplants and reduce diseases. Plant growth promotion effects of single, and combined, inoculation of the root colonizing endophytic fungus Piriformospora indica and bacterial root endophytes isolated from tomato (Solanum lycopersicum L.), chilli (Capsicum annuum L.), and eggplant (Solanum melongena L.) in seedlings were examined as an initial step for developing microbial inocula for transplant production. The isolates were screened for plant growth promotion ability after seed inoculation. Seedling vigor index was assessed by a roll towel assay followed by evaluation of seedling growth in extruded plastic seedling trays with sterile vermiculite as the planting medium. A compatibility test of bacterial endophytes with P. indica was performed by dual culture plate assay on potato dextrose agar medium. Four isolates from tomato, and 2 each from chilli and eggplant, had compatible reactions with the endophytic fungus. Performance of individual and combined inoculation of the root endophytic fungus and compatible endophytic bacteria in host plants was evaluated. Inoculation with microbial agents improved seedling growth. Combined inoculation of bacterial endophytes and fungal endophyte had no influence on the root colonization pattern of P. indica in tomato, chilli, and eggplant seedlings. Application of both crop-specific endophytic bacteria possessing plant growth promoting ability and root endophytic fungus P. indica improved development of tomato, chilli and eggplant seedlings.