Tarbiat Modares University (TMU) ECOPERSIA 2322-2700 14 3 2026 07 01 Enhancing Drought Resistance in Red Clover (Trifolium pratense L.) using Growth-Promoting Bacteria 217 235 29028 10.48311/ecopersia.2026.119757.82884 EN Mahdieh Ebrahimi Associate Professor, Department of Range and Watershed Management, Faculty of Water and Soil, University of Zabol, Zabol, Iran Malihe Erfani Department of Environment, Natural Resources Faculty, University of Zabol, Zabol, Iran Journal Article 2026 04 16 <strong>Aims:</strong> Arid environments present significant constraints on plant development, with water scarcity being a primary impediment. In this study, we investigated whether plant growth-promoting microorganisms (PGPRs) are effective in reducing the negative effects of water deficit on red clover (Trifolium pratense L.).<br><strong>Materials & Methods: </strong>A factorial test, using a completely randomized design, investigated the effect of PGPRs on seed germination, growth, and plant nutrient uptake under water deficit conditions. Three soil moisture regimes were established: field capacity 100% (FC100), 70% (FC70), and 40% (FC40). Experimental treatments comprised inoculation with Azotobacter vinelandii (AV), a consortium of Pantoea agglomerans and Pseudomonas putida (PA+PP), and AV+PA+PP.<br><strong>Findings:</strong> Germination rate varied considerably, with AV×FC70 exhibiting the highest percentage (93%) and control+FC70 the lowest (60%). Synergistic applications of AV, PA, and PP were less effective at mitigating drought stress than single treatments. Root length (10.79cm), shoot length (18.89cm), and dry biomass (aboveground: 0.98g.plant-1; belowground: 1.88g.plant-1) reached their maxima under AV×FC40, whereas (PA+PP)×FC40 yielded the minimal measurements. PA+PP demonstrated no statistically significant impact on water deficit reduction (p<0.01). AV×FC40 maximized potassium uptake. Iron and manganese were highest in (PA+PP)×FC70, while zinc was maximum in (AV+PA+PP)×FC100. Minimum uptake of iron, zinc, and manganese occurred with (AV+PA+PP)×FC70, (AV+PA+PP)×FC40, and AV×FC100, respectively.<br><strong>Conclusion: </strong>Typically, inoculation of red clover with A. vinelandii has demonstrated efficacy in enhancing drought tolerance, offering a biotechnological strategy for forage production in water-limited environments. Nevertheless, a comprehensive understanding of the mechanisms by which rhizobacteria confer drought resilience to host plants necessitates further investigation. https://ecopersia.modares.ac.ir/article_29028_bb9bc609d75ca1c73b0ab3da8d89d3fe.pdf