Key points are not available for this paper at this time.
Temperature significantly influences the germination, emergence, and growth of forage grasses. Plant growth-promoting rhizobacteria (PGPR) are widely recognized for their ability to enhance plant development and improve stress tolerance. This study evaluated the effects of a PGPR consortium on germination and seedling vigor of four forage grass species under contrasting temperature conditions. A 4 × 2 × 2 factorial experiment was conducted using annual ryegrass (Lolium multiflorum Lam.), tall fescue (Lolium arundinaceum (Schreb.) Darbysh), bermudagrass (Cynodon dactylon L.), bahiagrass (Paspalum notatum Flüggé), under two temperature regimes (low: 21 °C; high: 32 °C) and two inoculation treatments (with or without PGPR). The PGPR consortium included Bacillus altitudinis AP18, Bacillus subtilis AP278, Bacillus safensis AP280, and Lysinibacillus macroides AP282. Cool-season grasses (ryegrass and tall fescue) exhibited higher germination percentages (GP) and rates (GR) than warm-season species. High temperature improved GP and GR in bahiagrass and bermudagrass, had no significant effect on ryegrass, but reduced both parameters in tall fescue. Seedling length and vigor index (VI) were significantly reduced in ryegrass and tall fescue under high temperature. Although PGPR inoculation initially delayed germination, it significantly increased seedling length and VI in ryegrass by 35.6% and 25.8% at low temperature, and 13.9% and 22.1% at high temperature. Tall fescue showed similar improvements, with gains of 25.1% and 23.3% under low temperature, and 12.4% and 22.1% under high temperature. These findings suggest that PGPR can enhance seedling growth and mitigate heat stress in cool-season forage grasses, with promising implications for sustainable forage production under changing climatic conditions.
Satognon et al. (Sun,) studied this question.