Rooting Characteristics of Fescues, Ryegrasses and Their Hybrids for Improved Drought Tolerance.

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 tolerance. This increase was associated with the presence of an introgression of Fp chromatin on chromosome 3. This specific segment of Fp chromatin was associated with deep rooting, drought, and other abiotic stress tolerance in forage-type interspecific hybrids of fescues and ryegrasses in Europe.  A greenhouse study was conducted in 2010 to compare rooting characteristics of: our turf-type hybrid with introgression of Fp on the chromosome 3 (FL3S); a hybrid without introgression from Fp (FL0); the backcross parent (Lp ‘SR4220’); a representative Fp ‘Pasja’; and turf-type tall fescue (Festuca arundinacea Schreb.; Fa ‘Tulsa Time’) in 5-cm diameter x 160-cm deep PVC tubes containing sand under non-limiting irrigation. There were significant differences between experiments for most shoot and root measurements taken among the species which may have been attributed, at least in part, to flowering in the second experiment.  In general, both experiments revealed that Fp produced either numerically or statistically greater rooting depth, root biomass, and root:shoot ratio after 120 days. Conversely, Fa ranked at or near the bottom for these traits.  In between, there were little or no statistical differences among Lp, FL3S, and FL0.  Further studies are planned to evaluate these genotypes under field and greenhouse conditions in response to drought stress imposed by deficit irrigation.