Abstract
BACKGROUND: The use of Plant Growth-Promoting Rhizobacteria (PGPR) is one of the alternative strategies to mitigate the effects of drought. This study aimed to determine the effects of the Partial Root-Zone Drying (PRD) and conventional deficit irrigation techniques on dwarf bean by reducing drought stress through microbial fertilizer applications. The parameters evaluated included yield, plant water consumption, water use efficiency (WUE), irrigation water use efficiency (IWUE), plant growth characteristics, chlorophyll content and biochemical properties. The Gina dwarf bean variety (Phaseolus vulgaris L. cv. Gina) was used in the research conducted at Akdeniz University. Biofertilizers consisting of Pantoea agglomerans RK-92, Paenibacillus polymyxa TV-12E, Bacillus megaterium TV-6D and Pseudomonas fluorescens FDG-37 bacterial strains were supplied by Atatürk University Plant Protection Department. The study was planned with and without biofertilizer (BF) application, and five irrigation treatments were considered. Three conventional irrigation treatments were applied: 100% of the evaporation (I(100)), 75% of the evaporation (I(75)), and 50% of the evaporation (I(50)). And, two treatments were applied to Partial Root Zone Drying (PRD): 75% of the evaporation (PRD(75)) and 50% of the evaporation (PRD(50)). RESULTS: According to the research results, remarkable results were obtained from the biofertilizer treatments. The highest first-class (8.44 t ha(-1)) and total yield (10.50 t ha(-1)) was recorded from the BF-I(100) treatment. Compared to the control treatment (I(100)) with a first-class yield of 4.40 t ha(-1) and a total yield of 9.31 t ha(-1), the BF-I(100) treatment provided a 14.5% higher first-class yield and a 12.78% higher total yield. Similarly, compared to the control, the BF-I(75) resulted in higher first-class (7.36 t ha(-1); 6.6%) and total yields (9.34 t ha(-1); 9.88%). Among the deficit irrigation treatments, the highest total yield was recorded in the BF-PRD(75) (9.54 t ha(-1)) treatment with biofertilizer. The total yield obtained from BF-PRD(75) was 2.47% higher than that of the I(100) treatment and was one of the most striking results. The BF-PRD(50) treatment exhibited the highest WUE (11.26 kg m(-3)) and IWUE (13.88 kg m(-3)) for both first-class and total yield, with no statistically significant differences among BF-I(50), BF-I(100), and BF-PRD(50) treatments. CONCLUSIONS: In conclusion, growth, yield, and quality characteristics were significantly influenced by the irrigation treatments. Biofertilizer applications were effective under both optimized and deficit irrigation conditions. The ameliorative and drought-reducing effects of biofertilizer treatments were clearly observed. This study found that biofertilizers positively impact yield and quality, potentially enabling water savings of 25-50%. They can be effectively used in regions with drought-related water shortages.