Interactive effects of plant growth-promoting rhizobacteria and drought stress on the growth and yield of shallot (<i>Allium ascalonicum</i> L.) cultivated in saline soil

This study evaluated the effects of plant growth-promoting rhizobacteria (PGPR) and drought-stress timing on the growth, yield, and physiological responses of shallot (Allium ascalonicum L.) cultivated in saline soil.The experiment was conducted using a factorial randomized block design with PGPR concentrations of 0, 20, and 40 mL L⁻¹ and drought-stress timing consisting of no stress, early growth stress (1-14 DAP), vegetative stress (15-28 DAP), and bulb formation stress (29-42 DAP).The final soil EC reached 6 dS m⁻¹, while soil moisture during drought periods declined to 30-50%.PGPR improved plant length, leaf area, tiller number, plant dry weight, and net assimilation rate.PGPR at 40 mL L⁻¹ was more effective for vegetative growth, whereas 20 mL L⁻¹ tended to enhance proline and flavonoid accumulation.Drought during early and vegetative phases caused the greatest reductions in growth and yield.These findings indicate that PGPR supports shallot performance in saline soil, but its effectiveness depends strongly on water availability during critical growth phases.