Zinc solubilizing bacteria synergize the effect of zinc sulfate on growth, yield and grain zinc content of rice (Oryza sativa)

Zinc solubilizing bacteria inhabiting root endosphere possesses great potential to enhance plant yield by solubilizing the nutrients. The potential of Zn solubilizing bacteria Bacillus sp. SH-10 and Bacillus cereus SH-17 to improve yield and grain zinc content of rice was investigated under different regimes of individual and co-inoculation in the presence and absence of chemical fertilizer zinc sulfate (ZnSO4). The strains were applied to the rice varieties basmati 385 and super basmati under field conditions for two consecutive years. A significantly improved growth of rice plants, such as plant height (102-118 cm), number of tillers per plant (8.5-11.5), chlorophyll content (29.5-35.1), zinc requiring enzymes, i.e., superoxide dismutase (396-570 per gram fresh weight (g(-1) FW)), carbonic anhydrase activity (CA) (10-15.06 U g(-1) FW) and grain yield (3.0-3.8 tons ha-1), was observed in the plants inoculated with Bacillus sp. in the presence of chemical fertilizer (ZnSO4). Consortium of zinc solubilizing bacteria also caused higher grain Zn content (25.0-30.5 mg kg(-1)) of the rice varieties basmati 385 and super basmati as compared to that of un-inoculated plants. Hence, it can be concluded that Zn solubilizing bacteria has immense potential to be used as agricultural crop inoculants as they synergize the effect of chemical Zn, increase yield and improve the nutritional value of crops.