Dr. Gulab PandoveJaspreet Kaur2024-06-282024-06-282024Jaspreet Kaur (2024). Integrated nutrient management in forage Sorghum with the application of liquid biofertilizers (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810211112Forages are the foundation upon which the rumen-healthy livestock diets are formulated. Therefore, amelioration of forage quality via enhanced agronomic techniques, such as Integrated Nutrient Management (INM), is imperative.Thus, the present investigation was carried out to evaluate the influence of integrated nutrient management on forage Sorghum with the application of liquid biofertilizers on the yield and quality attributes. A total of 30 forage Sorghum plants were collected from different Sorghum fields of village Dhudike, Moga, Punjab, India and 17 bacterial endophytes were isolated based on distinct colony morphology. Subsequently, 15 isolates were selected on the basis of qualitative phosphate solubilisation assay and were further scrutinized for quantitative plant growth promoting traits such as IAA production, phosphate solubilization, production of gibberellic acid, ammonia and siderophore (catechol and hydroxamate), ACC deaminase activity, Zn solubilisation assay. Consequently, the potential isolate RPR_3 was selected on the basis of multiple PGP traits and identified by 16s RNA sequencing technique as Enterobacter sp. Furthermore, the identified bacterial culture Enterobacter sp. (JJG_Zn) along with the standard cultures of Burkholderia seminalis and Stenotrophomonas maltophilia, procured from the School of Organic farming, PAU were evaluated for the aforementioned PGP traits under abiotic stress conditions of salinity (0,50,100 and 150mM NaCl) and drought (0,5,10 and 15% PEG). All three PGPB were able to tolerate the stress conditions while optimum growth was recorded at 50mM NaCl and 5% PEG concentrations. Additionally, an in vitro experiment was carried out to study the efficacy of liquid bacterial inoculants (B. Seminalis, S. maltophilia and Enterobacter sp. (JJG_Zn)) in enhancing salt (0,50,100 and 150mM NaCl) and drought (0,5 and 10% PEG) tolerance in forage Sorghum seeds. The findings revealed that the seeds at 50mM NaCl salt stress when bio-primed with the treatment T5: dual inoculation (B. seminalis and S. maltophilia), exhibited superior germination and maximum plant growth parameters namely, germination percentage (92.53%), germination speed (2.74), mean germination time (2.94), shoot length (13.55cm), root length (13.41cm), as well as fresh and dry shoot (0.066g and 0.013g) and root weights (0.132g and 0.014g) respectively. Furthermore, at 5% PEG induced drought stress, the bio-priming with treatment T5: dual inoculation (B. seminalis and S. maltophilia) improved the germination percentage (92.45%), germination speed (2.82), mean germination time (2.66), shoot length (14.46cm), root length (14.12cm), as well as fresh and dry shoot (0.123and 0.014g) and root weights (0.073and 0.014g) respectively. Scanning electron microscopy was employed to examine the degree of root colonization in forage Sorghum by liquid bacterial cultures under gnotobiotic conditions. The SEM micrographs demonstrated that Enterobacter sp. (JJG_Zn) exhibited the highest level of root surface colonization, followed by B. seminalis and S. maltophilia. Before commercializing PGPB-based products in the markets, it is essential to conduct thorough characterization and biosafety analysis .In this context, the Plant Growth-Promoting Bacteria (PGPB) B. seminalis, S. maltophilia, and Enterobacter sp. (JJG_Zn), were evaluated for various bio safety tests such as E.coli sensitivity assay, ecotoxicity test in earthworms and pathogenitcity test on Albino mice. Furthermore, sheep blood agar biochemical assay was also performed and all the tests displayed negative results for the three PGPB thereby characterizing them as potentially non-pathogenic. Field experiments were conducted at Punjab Agricultural University, Regional Research Station, Bathinda, and School of Organic Farming, IFS, Punjab Agricultural University, Ludhiana during kharif 2022. The experiment employed a randomized complete block design, encompassing a total of 11 treatment combinations involving liquid bacterial inoculants (S. maltophilia, B. seminalis, and Enterobacter sp. (JJG_Zn)) at 100% and 75% recommended dose of fertilizer (RDF), with three replications. Notably, the treatment T11: 75% RDF + dual inoculation (B. seminalis + S. maltophilia), exhibited superior growth, yield and quality attributes such as emergence count, plant height, number of leaves, chlorophyll content, leaf-to-stem ratio, leaf breadth, leaf length, dry matter accumulation per plant, total sugars, ash content, crude protein content, and in vitro dry matter digestibility (IVDMD). Whereas, a significant decrease in acid detergent fiber (ADF), neutral detergent fiber (NDF), and a noteworthy reduction in total phenols was observed. In the pooled analysis of green fodder and dry matter yield at both the locations, the treatment T11 demonstrated a 10.23% and 15.79% increment as compared to the control (T1).The liquid bacterial inoculants ameliorated the physicochemical properties of the soil (pH, electrical conductivity, and organic carbon content) and also enhanced the nutritional status (N,P,K). Furthermore, the treatment T11 also demonstrated increased root colonization by arbuscular mycorrhizal fungi. Hence, it can be inferred that liquid bacterial inoculants is a promising strategy for enhancing the productivity and quality of forage Sorghum.EnglishThesis