Application of inorganic carrier-based formulations of fluorescent pseudomonads and Piriformospora indica on tomato plants and evaluation of their efficacy

Aims: Fluorescent pseudomonads are widely used as bioinoculants for improving plant growth and controlling phytopathogenic fungi. Piriformospora indica (Pi), a symbiotic root endophyte, also has beneficial effects on a number of plants. The present study focuses on the improvement of growth yields of tomato plants and control of Fusarium wilt using inorganic carrier-based formulations of two fluorescent pseudomonad strains (R62 and R81) and Pi. Methods and Results: The inorganic carrier-based formulations of pseudomonad strains and Pi were tested for plant growth promotion of tomato plants under glass house and field conditions. In controlled glass house experiments, 8·8-fold increase in dry root weight and 8·6-fold increase in dry shoot weight were observed with talcum powder-based consortium formulation of R81 and Pi. Field trial experiments ascertained the glfass house results with a considerable amount of increase in plant growth responses, and amongst all the treatments, R81 + Pi treatment performed consistently well in field conditions with an increase of 2·6-, 3·1- and 3·9-fold increase in dry root weight, shoot weight and fruit yield, respectively. The fluorescent pseudomonad R81 and Pi also acted as biocontrol agents, as their treatments could control the incidence of wilt disease caused by Fusarium oxysporum f.sp. lycopersici in tomato plants under glass house conditions. Conclusions: The culture broths of pseudomonads R62, R81 and Pi were successfully used for development of talcum- and vermiculite-based bioinoculant formulations. In controlled glasshouse experiments, the talcum-based bioinoculant formulations performed significantly better over vermiculite-based formulations. In field experiments the talcum-based consortium formulation of pseudomonad R81 and Pi was most effective. Significance and Impact of the Study: This study suggests that the formulations of pseudomonad strains (R62 and R81) and Pi can be used as bioinoculants for improving the productivity of tomato plants. The application of such formulations is a step forward towards sustainable agriculture.