The Influence of PEG-Induced Drought Stress on Seed Germination and Seedling Growth Traits of Tetraploid Annual Ryegrass Cultivars
ÖZKAN, Şükrü Sezgi | LEVENT, Kaan
Drought stress poses a significant challenge to global forage production, particularly under climate change conditions. Identifying cultivars with superior drought tolerance is essential for maintaining productivity in water-limited environments. The objective of the study was to evaluate the effects of polyethylene glycol (PEG)-induced drought stress on the germination and seedling growth traits of tetraploid annual ryegrass (Lolium multiflorum Lam.) cultivars. Four cultivars (Baqueano, Big Boss, Elif, and Medoacus) were exposed to seven osmotic potential levels (0, -0.2, -0.4, -0.6, -0.8, -1.0, and -1.2 MPa) under controlled conditions. Germination rate (%), mean germination time (day), shoot and root length (cm), shoot-to-root ratio, seedling fresh weight (mg), vigor index, and drought tolerance index (%) were determined. The results revealed significant reductions in germination and seedling growth traits with increasing drought stress. Among the cultivars, Baqueano and Big Boss cultivars exhibited superior drought tolerance, maintaining higher vigor and drought tolerance indices. An osmotic potential of -0.6 MPa reduced the drought tolerance index by up to 44.5%, with no germination observed at -1.2 MPa. Strong correlations were identified among germination rate, shoot and root length, vigor index, and drought tolerance index, highlighting their importance as indicators of drought resilience.
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