Proceedings of the National Academy of Sciences, India Section B: Biological Sciences

A study was conducted to evaluate the effect of seed treatment with bacterial strains of Enterobacter spp. on seed germination and seedling growth of two tomato (Solanum lycopersicum L.) cultivars (cv. Arka Meghali and cv. Pusa Ruby). The cultivar Arka Meghali is recommended for rainfed conditions, while cv. Pusa Ruby is grown under irrigated conditions. Seeds were treated with osmotolerant plant growth promoting bacterial strains belonging to the genus Enterobacter (P-39, P-41 and P-46), for a period of 24 h and subsequently incubated at 25 °C under different mannitol induced osmotic stresses (0, −0.2, −0.4, −0.6, −0.8, −1.0 MPa). Seed treatment with bacterial strains influenced the germination and seedling vigour index of both cultivars as compared to the untreated and hydro-primed seeds, up to −0.6 MPa. The response of Enterobacter strains to water stress was better in cv. Pusa Ruby as compared to cv. Arka Meghali as indicated by higher germination percentage and germination rate. The seeds of both cultivars treated with Enterobacter P-39 performed better under osmotic stress (up to −0.6 MPa in cv. Arka Meghali and −0.8 MPa in cv. Pusa Ruby), indicating the significance of this strain as compared to other bacterial strains studied. The bioprimed seeds that failed to germinate at osmotic potentials beyond −0.4 MPa, when transferred to water (0 MPa), recorded improved germination and seedling vigour. These results indicated that the treatment of seeds with osmotolerant plant growth promoting bacterial strains improved the germination and enhanced seedling growth under osmotic stress conditions.