o:6630 Plant growth promotion of wheat seedlings using Bacillus inoculants en Abstract: Wheat (Triticum aestivum L.) is one of the most widely grown crops used in human diet due to its high protein and energy content. With a growing world population and food demands, enhancing the production potential of wheat is of great importance for agriculture. Microbial inoculants based on plant growth promoting bacteria (PGPB) have emerged as an eco-friendly alternative for sustainable production of cereals. One of the most significant traits of PGPB is the production of indole-3-acetic acid (IAA), as it triggers the seed germination, controls plant cell division and tissue differentiation during early development stages. Therefore, the aim of this research was to evaluate the effects of IAA-producing Bacillus spp. isolates on seed germination and seedlings growth. Bacillus spp. BHC 9.1 and BHC 5.4 were isolated from mildly alkaline soil and alkaline soil, respectively. The ability of isolates to produce IAA was quantified spectrophotometrically using Salkowski reagent method. The ability of bacterial isolates to induce seed germination and seedlings growth of wheat was evaluated in vitro on Petri dishes by filter paper method and results were expressed as relative germination index (RSGI%) and length of shoots and roots. Isolates BHC 9.1 and BHC 5.4 were characterized as IAA producers (1.81 and 6.55 μg mg-1, respectively). Application of both bacterial treatments increased germination of wheat seeds in vitro. Relative seed germination index of wheat seeds treated by isolate BHC 9.1 and BHC 5.4 was 110.5% and 101.3%, respectively. The highest increment of shoots was recorded for BHC 9.1 inoculation (19.5%), while BHC 5.4 increased roots length for up to 12.3%, in comparison to the control. These results indicate the potential of selected Bacillus spp. isolates to enhance germination of wheat seeds. Future studies should aim to enhance the efficiency of Bacillus-based bio-inoculants under semi-controlled and field conditions, providing sustainable agricultural practices. Bio-inoculants; early plant development; indole-3-acetic acid; seed germination; sustainable agriculture 2024-12-17T08:06:11.648Z 44 no 46 Marina Jovković Institute of Soil Science 0000-0001-7224-8556 46 Magdalena Knežević Institute of Soil Science 0000-0003-0186-3652 46 Marina Dervišević Institute of Pesticides and Environmental Protection, Belgrade, Serbia 46 Jelena Maksimović Institute of Soil Science 0000-0001-5217-3972 46 Galina Jevđenović University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia 46 Aneta Buntić Institute of Soil Science 0000-0002-7068-1804 application/pdf 1056840 https://unilib.phaidrabg.rs/o:6630 no yes 1 70 92000004 71A05 International Soil Science Symposium on Soil Science & Plant Nutrition (10th International Scientific Meeting); 13 – 14 December 2024 Samsun, Türkiye 19 19 2024