University of Tabriz Journal of Agricultural Science and Sustainable Production 2476-4310 Articles in Press 2027 04 20 Effect of potassium releasing, phosphate solubilizing and nitrogen fixing bacteria on vegetative characteristics and nutrient uptake of tomato plants under field conditions Effect of potassium releasing, phosphate solubilizing and nitrogen fixing bacteria on vegetative characteristics and nutrient uptake of tomato plants under field conditions 21459 10.22034/saps.2025.67818.3375 FA Mortaza Sheikhalipour Postdoctoral Researcher - University of Tabriz Saheb Ali Bolandndnazar Professor, Department of Horticultural, Faculty of Agriculture, University of Tabriz, Iran Mohammad Reza Sarikhani Professor, Department of Soil Science, University of Tabriz, Tabriz, Iran Jaber Panahandeh Professor, Department of Soil Science, University of Tabriz, Tabriz, Iran 0000-0001-7788-5300 Journal Article 2025 06 12 Potassium releasing, phosphate solubilizing and nitrogen fixing bacteria play an important role in the supply of nutrients requirement for plants. In order to evaluate the effect of potassium releasing, phosphate solubilizing and nitrogen fixing bacteria on growth, nutrient uptake and yield of tomato, an experiment has been carried out based on randomized complete block design with 9 treatments and 3 replications. <br />In this experiment, tomato (Lycopersicon esculentum Mill cv. Super Chief) seeds were inoculated with single and combined treatments of the potassium releasing (KSB: Pseudomonas sp. S19-1, Pseudomonas sp. S14-3) and phosphate solubilizing (PSB: P. putida Tabriz, P. fluorescence Tabriz) and nitrogen fixing bacteria (NFB: Azospirillum sp. Acu9, Azotobacter sp.). Moreover, the control treatment without bacteria inoculation (negative control) and fertilizer treatment according to soil test (positive control) in order to comparison were considered. <br />The results showed that the application of all three species of bacteria on characters such as yield of plant, shoot dry and fresh weight, leaf area, chlorophyll index, nitrogen, phosphorus and potassium percentage in the leaf was significant and the highest yield was in KSB treatment , the highest leaf area, chlorophyll index and phosphorus was in PSB+KSB treatment, the highest shoot fresh and dry weight and K was in NFB+PSB+KSB treatment and the highest N was in NFB treatment .<br />According to the results of this study, the potassium-releasing, phosphate-solubilizing, and nitrogen-fixing bacteria can be used as biofertilizers to improve nutrient uptake, leaf area, chlorophyll and yield (by 31/89%) of tomato. Potassium releasing, phosphate solubilizing and nitrogen fixing bacteria play an important role in the supply of nutrients requirement for plants. In order to evaluate the effect of potassium releasing, phosphate solubilizing and nitrogen fixing bacteria on growth, nutrient uptake and yield of tomato, an experiment has been carried out based on randomized complete block design with 9 treatments and 3 replications. <br />In this experiment, tomato (Lycopersicon esculentum Mill cv. Super Chief) seeds were inoculated with single and combined treatments of the potassium releasing (KSB: Pseudomonas sp. S19-1, Pseudomonas sp. S14-3) and phosphate solubilizing (PSB: P. putida Tabriz, P. fluorescence Tabriz) and nitrogen fixing bacteria (NFB: Azospirillum sp. Acu9, Azotobacter sp.). Moreover, the control treatment without bacteria inoculation (negative control) and fertilizer treatment according to soil test (positive control) in order to comparison were considered. <br />The results showed that the application of all three species of bacteria on characters such as yield of plant, shoot dry and fresh weight, leaf area, chlorophyll index, nitrogen, phosphorus and potassium percentage in the leaf was significant and the highest yield was in KSB treatment , the highest leaf area, chlorophyll index and phosphorus was in PSB+KSB treatment, the highest shoot fresh and dry weight and K was in NFB+PSB+KSB treatment and the highest N was in NFB treatment .<br />According to the results of this study, the potassium-releasing, phosphate-solubilizing, and nitrogen-fixing bacteria can be used as biofertilizers to improve nutrient uptake, leaf area, chlorophyll and yield (by 31/89%) of tomato.