The role of nitrate-reducing bacteria in optimizing urea fertilizer use and increasing tomato plant growth

With the rising cost of chemical fertilizers and their negative impact on the environment, there is growing interest in the use of beneficial microorganisms to enhance soil and plant fertility. The present study showed that bacterial isolates can produce auxin and solubilized phosphate, which increases germination and plant growth indices under laboratory and greenhouse conditions. To investigate the effects of different nitrogen fertilizer rates on yield and nitrate accumulation in tomato plants, an experiment with eight bacterial treatments and three rates of zero, 300, and 900 kg urea per hectare was set up in a completely randomized factorial trial with three replicates in the greenhouse. Results showed that the growth-promoting bacteria significantly increased shoot dry weight and nitrate concentration in the absence of nitrogen fertilizer compared to the non-inoculated control. Evaluation of nitrate content in the plants showed that excessive fertilization with more than 300 kg of urea may lead to nitrate accumulation in the control plants. In all bacterial treatments, nitrate levels were lower than in the untreated control, even when three times the recommended amount of fertilizer was applied. In conclusion, plant probiotic isolates in integrated nitrogen fertilizer management systems can improve fertilizer efficiency and yield and reduce nitrate accumulation in plants