Temperature‐Dependent Growth Adaptation of Festuca pratensis from the Biophysical Viewpoint
2011
Šimkūnas, A. | Valašinaitė, S. | Švitra, D.
Meadow fescue (Festuca pratensis), Italian ryegrass (Lolium multiflorum), their hybrid Festulolium braunii and perennial ryegrass (Lolium perenne) were grown hydroponically under vegetative (20 °C) and hardening (8 °C, 0 °C) regimes. The relative shoot/root growth ratio K, linear root growth rate and other parameters were estimated. When the temperature was lowered from 20 °C to 8 °C, the relative shoot/root growth ratio K of F. pratensis decreased to 0.6, i.e. much more than that of Lolium, suggesting that at 8 °C F. pratensis shoot growth blockage occurs. Further, by dropping the temperature from 8 °C down to 0 °C, the K ratio of F. pratensis increased significantly, while the linear root growth rate decreased much more markedly than in the other species – it suggests also a blockage of root growth. This growth slowdown of stress‐tolerant F. pratensis shoots and at a lower temperature also of its roots is inadequate to the direct impact of temperature and, thus, indicates a two‐step qualitative reorganization, i.e. transition into a qualitatively new state of stress. This phenomenon does not manifest itself in the less stress‐tolerant Lolium and Festulolium species but is expressed in stress‐tolerators, allowing them to achieve their strategic goal – to survive under extreme conditions.
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