Drought Stress Response of Turf-Type Perennial Ryegrass Genotypes in a Mediterranean Environment

Perennial ryegrass is generally known as exhibiting poor drought tolerance with poor recuperative capacity. The objective of this study was to evaluate the effects of acute drought followed by a recovery period, on 11 perennial ryegrass varieties (Apple SGL, Azimuth, Barrage, Caddieshack, Double, Double Time, Ecologic, New Orleans, Pizzaz 2, Rainwater, Turfgold) and one tall fescue (Olympic Gold). The study was conducted in a rain-out structure to control water inputs. Green cover percentage, visual quality, color, normalized difference vegetation index (NDVI), and soil moisture were measured weekly. Eighty percent coverage was considered optimal and was reached only during the first two weeks of the drought period. Starting from the fourth week, a significant decrease in green cover was observed for most of the perennial ryegrass cultivars. However, 5 cultivars displayed a visual quality rate greater than 6, which is considered acceptable during this period, while color ratings were recorded greater than 6 for 7 cultivars. At the end of the drought phase, the cultivar ’New Orleans’ exhibited significantly greater green cover compared to most other perennial ryegrasses. The recovery of the grasses was slow and at the end of the experiment the variability in green cover between cultivars was greater than during the first week.