Drought Tolerance of Fescues, Ryegrasses, and Their Hybrids Under Field Deficit Irrigation.

By recurrent selection for drought and heat tolerance among hybrids of perennial ryegrass (Lolium perenne L.; Lp) with meadow fescue (Festuca pratensis Huds.; Fp), we have developed a population of Lp with a marked increase in drought and heat tolerance. This increase was associated with the presence of an introgression of Fp chromatin on chromosome 3.  A field study was conducted in 2010 to evaluate the degree of drought and heat tolerance in response to deficit irrigation  (50-70% ET_o) among: four populations of our turf-type hybrid with introgression of Fp on chromosome 3 (FL3S); the backcross parent (Lp ‘SR4220’); a drought tolerant Lp ‘Zoom’; a representative Fp ‘Pasja’; and three turf-type tall fescue (Festuca arundinacea Schreb.; Fa) cultivars ‘Tulsa Time’, ‘Speedway’, and ‘Grande II’.  During most rating dates, turf quality was significantly higher in the populations of FL3S, Lp ‘SR4220’, and Lp ‘Zoom’ compared to the Fa cultivars and Fp.  This trend was opposite for clipping dry weights harvested from the plots at all rating dates.  There were no significant differences when comparing roots sampled from three depths.  Overall, our FL3S populations appeared to offer higher turf quality and faster recovery than the Fa cultivars and Fp under drought conditions.  However, all FL3S populations did not show significantly higher turf quality compared to their parent line, Lp ‘SR4220’.  The field study will be repeated in 2011.