The use of 5-aminolevulinic acid to reduce heat-stress-related damages in tall fescue

Heat stress is a major abiotic stress that damages cool-season turfgrasses, such as tall fescue (Festuca arundinacea Schreb.), during summer months. Heat stress results in oxidative damage, reductions in photosynthesis, and ultimately can cause plant death. Exogenous applications of 5-aminolevulinic acid (ALA) have previously been demonstrated to improve abiotic stress tolerance in a number of crops by improving chlorophyll levels and reducing oxidative damage, two major indicators of heat stress in plants. Experiments were conducted in growth chamber conditions to determine the effect of ALA application on heat stress in tall fescue plants and to confirm if ALA could alleviate damage related to inhibited photosynthesis or oxidative damages associated with high temperature. A rate of 100 mg L-1 ALA was determined to be effective in eliciting positive tall fescue responses during heat stress with plants maintaining better visual characteristics. Plants treated with ALA had greater levels of chlorophyll as well as photosynthetic performance under heat stress than plants that were not treated with ALA. Additionally, ALA plants had reduced oxidative damage associated with greater antioxidant activities of the enzymes catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR). The use of ALA was demonstrated to be effective in reducing heat stress related damages in tall fescue.