Effect of zinc solubilizing bacteria on growth promotion and zinc nutrition of rice

A comparison study between the isolated indigenous bacteria and chemical Zn fertilizer (ZnSO4 center dot 7H(2)O) was conducted to evaluate their potential to augment Zn nutrition of Zn responsive (NDR 359) and Zn non responsive (PD 16) varieties of rice under the green house. Three bacterial strains namely; BC, AX and AB isolated from a Zn-deficient rice-wheat field belonging to the genera Burkholderia and Acinetobacter were investigated for the growth promotion and Zn uptake in rice plants. The plant growth promotory properties such as Zn solubilization and IAA production of the isolates was checked in a previous study. These three isolates when used individually or in combination were found effective in significantly increasing the mean dry matter yield/pot (12.9%), productive tillers/plant (15.1%), number of panicles/plant (13.3%), number of grains/panicle (12.8%), grain yield (17.0%) and straw yield (12.4%) over the control and Zn fertilizer treatment, respectively. Bacterial inoculations also significantly enhanced the total Zn uptake/pot (52.5%) as well as grain methionine concentration (38.8%). Effect of bacterial treatments on the bioavailability of Zn was assessed by estimating the levels of phytic acid in grains. A reduction of nearly 38.4% in phytate: Zn ratio in grains was observed under bacterial inoculations.