Singh, MahendraChanchal, Ankesh Kumar2023-02-162023-02-162021https://krishikosh.egranth.ac.in/handle/1/5810193880Zinc is the micronutrient which is essential for the survival of not only for plant but also important for human population as means to overcome the widespread problem of malnutrition. The zinc solubilizing bacteria are the cost effective and environment friendly option for combated the problems by converting the unavailable form of zinc into available form by the process of solubilization. This study involving isolation, characterization of zinc solubilizing bacterial isolates including two checks for their ability of zinc solubilization. The isolated ZnSBs were molecularly identified with the help of 16S rRNA gene sequencing namely Peribacillus simplex strain BAU_A1 (Accession number: OK037153), Bacillus sp. strain BAU_A2 (Accession number: OK037154), Priestia megaterium strainBAU_A3 (Accession number: OK037165) and Bacillus subtilis strain BAU_A5 (Accession number: OK037166). These isolates effectively solubilized the considerable amount of zinc oxide (ZnO) ranging from 55.80 to 62.41 mg kg-1 and zinc phosphate Zn(PO4)2 ranging from 42.09 to 56.56 mg kg-1 and zinc carbonate (ZnCO3) 42.78 to 51.12 mg kg-1 under optimal laboratory conditions. All seven isolates were able to produced Indole Acetic Acid (IAA) ranging from 13.66 to 24.95 (µg ml−1) and Gibberellic Acid (GA) ranging from 9.66 to 18.50 (µgml-1). The efficiency of most potent bacteria (ZnSB1-Peribacillus simplex strain BAU_A1, ZnSB2-Bacillus sp. strain BAU_A2 and ZnSB3-Bacillus subtilis strain BAU_A5) also had been evaluated in the field condition with rice crop at Bihar Agricultural University, Sabour, Bhagalpur. The experimental findings revealed that the application of treatment T5 (100 % RDF+ ZnSB2 @ 750 ml ha-1) showed the maximum dehydrogenase activity (56.81 µg TPF g-1 soil h-1), alkaline phosphatase activity (27.23 µg PNP g-1 soil h-1) and acid phosphatase activity (28.42 µg PNP g-1 soil h-1) at panicle initiation stage. The application of T4 (100 % RDF+ ZnSB1 @ 750 ml ha-1) produced highest water soluble and exchangeable fraction of zinc (0.65 mg kg -1) followed by treatment T5 (100 % RDF + ZnSB2 @ 750 ml ha-1). Although the highest organically bounded zinc (3.69 mg kg -1) was observed under control treatment and while lowest (2.33 mg kg -1) was recorded with T5 (100 % RDF + ZnSB2 @ 750 ml ha-1). Similarly, Mn-Oxide bounded zinc (0.1M NH2OH.HCl) was found to be statistically at par (p=0.05) with each other. Perhaps the application of treatment T6 (100 % RDF + ZnSB3 @ 750 ml ha-1) was having highest concentration (3.72 mg kg-1) among all treatments. The highest concentration of Crystalline Fe-oxide was found in soil which was treated with the treatment T3 (100 % RDF + 25 kg ZnSO4.7H2O) while the lowest concentration of 4.08 mg kg-1 was found with the treatment T2 (100 % RDF). The application of treatment T5 (100 % RDF+ ZnSB2 @ 750 ml ha-1) gave highest grain yield (4555.00 kg ha-1), zinc concentration in rice grain (27.45 mg kg-1) zinc uptake by rice grain (0.13 mg kg-1), DTPA Zn (0.85 mg kg-1) and also produced maximum microbial population, respectively. However, this dataset originates from single season experiment, so more holistic approach is needed to draw a conclusion amongst these applied treatments on the basis of various field and climatic conditions.EnglishThesis