Co-inoculation of multi-trait plant growth promoting rhizobacteria promotes growth and nutrient assimilation of transplant Aman rice (cv. BRRI dhan49)

Abstract

Plant growth-promoting rhizobacteria (PGPR) are the rhizosphere bacteria that can enhance plant growth by a wide range of mechanisms. This study was conducted to assess the enhancement of PGPR on growth and nutrient assimilation of rice. Seeds of transplant Aman rice (cv. BRRI dhan49) were collected from Bangladesh Rice Research Institute (BRRI). A pot experiment was conducted with rice plants inoculated with two PGPR isolates MQ1 (zinc solubilizing, IAA producing, phosphate solubilizing and N₂-fixing) and MQ2 (zinc solubilizing, phosphate solubilizing and N₂-fixing) alone and in a consortium (PGPR_CONS.= both MQ1 and MQ2) with addition of three different levels of chemical fertilizers (RF_0.0 = no fertilizer, RF_0.5 = half of the recommended dose, and RF1.0 = full of the recommended dose) following Completely Randomized Design with three replications. Plant height at different days after transplanting, number of tillers hill^-1 and biomass yield were recorded. Plant samples were analyzed for N, P, Ca, Mg, S, Fe, Zn, Mn, Cu and Cd contents. Rice plants inoculated with the PGPR both individually or in consortium along with different doses of fertilizers showed improved plant growth and increased biomass production. The highest plant height and the maximum number of tillers hill^-1 were recorded in PGPR_MQ1RF_1.0 treatment and the highest biomass production was recorded in PGPR_CONS.RF_1.0. Nitrogen content and uptake of the individual PGPR inoculated rice plants were also found to be higher in comparison with the uninoculated control plants. Besides these Fe and Zn content of the treated rice plants was also found to be higher in comparison with the uninoculated control plants. N, P, Fe , Zn and Mn uptake were observed higher in PGPR_MQ1RF_1.0 treatment comparing with the uninoculated control plants. PGPR inoculation has immense potential to be used as rice crop inoculants as they promote plant growth as well as nutrient assimilation of rice.