Effect of Biofertilization with Plant Growth-Promoting rhizobacillus (PGPR) on Growth and Productivity of maize (Zea mays L.) Compared to Chemical Fertilization
Background: Maize (Zea mays L.) is one of the world's most important cereal crops, and improving its productivity while reducing dependence on chemical fertilizers has become a major goal of sustainable agriculture. The potential role of plant growth promoting rhizobacteria (PGPR) as a biofertilizer evolved as appropriate substitute to neutralize adverse environmental impacts wielded by manmade agrochemical. Objective: This study aimed to evaluate the effects of Pseudomonas fluorescens and Bacillus subtilis, individually and in combination, on the growth and yield of maize compared with conventional NPK fertilization. Methods: A field experiment was conducted during the 2025 growing season at the Field Crops Research Station, College of Agriculture, University of Samarra, using a Randomized Complete Block Design (RCBD) with three replicates. Six treatments were evaluated: Untreated control (T1), Pseudomonas fluorescens (T2), Bacillus subtilis (T3), combined inoculation (P. fluorescens + B. subtilis) (T4), combined inoculation with NPK fertilizer (T5), and NPK fertilizer (20:20:20) only (T6). Vegetative growth and yield-related traits were recorded and statistically analyzed. Results: Inoculation of plants with PGPR bacteria resulted in a significant improvement in both vegetative growth and yield compared to the untreated control group. Pseudomonas fluorescens (T2) exhibited the highest vegetative growth rate, recording the highest plant height (148.00 cm), leaf area (365.00 cm²), leaf area index (2.63), and number of grains per spike (688 grains) compared control group recorded (92.33 cm), (10.67 plant⁻¹), (151.73 cm²), (0.70) respectively. Bacillus subtilis (T3), achieved the highest productivity, producing the largest number of spikes per plant (2.67 spikes) and the highest spike weight (283.50 g) compared control group recorded (2.00) and (161.60 g). Conclusion: The use of PGPR, and especially Pseudomonas fluorescens and Bacillus subtilis as potential biofertilisation agents is a promising sustainable alternative to chemical fertilisation that can enhance maize growth and production, while decreasing dependence on mineral fertilisers.