Correlation of Heat and Cold Tolerance in Iranian Tall Fescue Ecotypes with Reactive Oxygen Species Scavenging and Osmotic Adjustment

Abstract

<jats:p>Excessive heat or cold usually reduces the growth and quality of turfgrass. Genetic variations along with efficient biochemical and physiological mechanisms can diversify the tolerance to heat and cold. This study examined the effects of heat and cold stress on several biochemical and physiological parameters in Iranian tall fescue ecotypes (<jats:italic>Festuca arundinacea</jats:italic> L.). The control group of plants was maintained under optimal temperatures, whereas other groups were exposed to heat or cold in a growth chamber. The experiment was designed as a split plot, with stress treatments as the main plots and ecotypes as subplots. Physiologically and biochemically, the results revealed that three ecotypes (‘FA1’, ‘FA3’, and ‘FA5’) of the eight ecotypes examined in this study had better abilities to survive the simulated heat and cold stress. Better tolerance to heat and cold in the ‘FA1’, ‘FA3’, and ‘FA5’ ecotypes were probably due to higher levels of enzymatic and nonenzymatic antioxidant activities, maintenance of lower levels of malondialdehyde (MDA) and hydrogen peroxide (H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>), higher levels of proline and total nonstructural carbohydrates (TNC), along with a more efficient osmotic adjustment. Diamine oxidase (DAO) and polyamine oxidase (PAO) activities increased significantly in ‘FA1’, ‘FA3’, and ‘FA5’ ecotypes. In summary, the strength of tolerance among ecotypes can be ranked as ‘FA1’ &gt; ‘FA3’ &gt; ‘FA5’ &gt; ‘FA2’ &gt; ‘FA6’ &gt; ‘FA4’ &gt; ‘FA7’ &gt; ‘FA8’ under heat stress and ‘FA5’&gt; ‘FA1’ &gt; ‘FA3’ &gt; ‘FA2’ &gt; ‘FA4’ &gt; ‘FA6’ &gt; ‘FA7’ &gt; ‘FA8’ under cold stress.</jats:p>