Effect of seed bio-priming with PGPR on seedling establishment of finger millet under drought

Abstract:

An often-overlooked observation in dryland cereal agronomy is that seeds which have been soaked with beneficial bacteria before sowing tend to establish faster and tolerate early-season drought better than untreated seeds—even before the bacteria have had time to colonise roots extensively. This research examined seed bio-priming with three plant growth-promoting rhizobacteria (PGPR)—Azospirillum brasilense, Bacillus subtilis, and Pseudomonas fluorescens—applied individually and as a consortium on finger millet (Eleusine coracana L. Gaertn.) seedling establishment under simulated drought (−0.6 MPa, PEG-6000). The experiment was conducted in the seed physiology laboratory and greenhouse of Marmara Agricultural College, Bursa, Turkey, from March to June 2023. Seeds were soaked in bacterial suspensions (10⁸ CFU mL⁻¹) for 12 h at 28°C, air-dried, and sown in pots filled with sandy loam. Drought was imposed at 7 days after sowing. The consortium treatment achieved the highest germination (96.4%), shoot length (14.8 cm), root length (18.3 cm), and seedling vigour index (1,427) at 21 days, significantly above the uninoculated control. Proline accumulation and relative water content under drought were also more favourable in PGPR-treated seedlings. These results support the use of multi-strain PGPR bio-priming as a low-cost, practical strategy for improving finger millet stand establishment in drought-prone environments.