Includes bibliographical references and index.

In the present study, nano-cellulose was prepared from paddy straw and further encapsulated with ZnO nanoparticle bioactive molecule of PGPR (ZnO-NPBF) to form nanocellulose encapsulated ZnO nanoparticle bioactive molecule of PGPR (NC-En-ZnO-NP-BF) with an aim for target delivery of ZnO-NP-BF against Ralstonia solanacearum. Prior to the synthesis of nano-cellulose, cellulose was prepared from paddy straw by 4-step method. This was further characterized with the help of stereo microscope, FTIR (Fourier transformed infrared spectroscopy) and chemical confirmation test and could able to develop four types of nanocellulose (viz., NC- AH, NC-AP, NC-MAH and NC-NW) by four different methods from cellulose fibers. All the products were characterized by Zeta potential and DLS (Zeta sizer). SEM results showed that the surface morphology of the nanoparticle had needle and sheet like configurations. NC-MAH was encapsulated with ZnO-NP-BF with one step hydrothermal method to form NC-En-ZnO-NP-BF. Characterization of NC-En-ZnO-NP-BF was also done by Zeta potential and DLS which revealed the values as 1.20 mV, 2407 nm with PDI value of 0.375. SEM results of NC-En-ZnO-NP-BF revealed that rough and corrugated surface morphology. In-vitro efficacy of both ZnO-NP-BF and NC-En-ZnONP- BF was tested at different concentrations and result showed that both were effective against R. solanacearum at 40 ppm. Catalase value of the bacterial pathogen was lowest (0.028 unit/ml) in case of treatment with NC-En-ZnO-NP-BF at 40 ppm. Similar results were obtained for all the biochemical tests in pot assay as well as of yield for the crop potato against R. solanacearum with an exception in case of highest total soluble sugar (25.010 μg/ml, 25.130 μg/ml and 24.120 μg/ml) at 40 ppm, 20 ppm and 50 ppm concentration of NC-En-ZnO-NP-BF. ROS (superoxide radical) formation was more prominent in case of treatment of the bacterial pathogen with 40 ppm concentration of NC-En-ZnO-NP-BF. The application of NC-En-ZnO-NP-BF at 40 ppm resulted increase of total soluble protein (24.465 μg/ml), flavonoids (866.111 μg/ml), terpenoids (26.619 μg/ml) and phenol (1.147 μg/ml) content. Soil microbial population was found to be highest in case of treatment with NC-En-ZnO-NP-BF at 40 ppm, 20 ppm and 50 ppm which were statistically at par (10.186, 10.226 and 10.156 log cfu/ml). Effect of NC-En- ZnO-NP-BF and ZnO-NP-BF on yield of potato was inversely proportional to disease incidence in pot assay. NC-MAH was compatible with bio control agents such as B. bassiana, M. robertsii, L. lecanii and T. harzianum.