Differential Tolerances of Turfgrass Cultivars to an Acid Soil High in Exchangeable Aluminum1

Abstract Soil acidity is a major problem in establishing and maintaining turfgrass in many areas. Aluminum toxicity is probably the most important factor limiting growth of turfgrass in many, if not most, acid soils, particularly below pH 5.0. Liming turfgrass soils to pH 6.0, or higher, to detoxify Al, is not always economically feasible. A promising alternative or supplementary approach is to select or develop cultivars tolerant to Al. To explore the possibilities of this approach, 35 Kentucky bluegrass (Poa pratensis L.), 15 fineleaf fescue (Festuca rubra L.), and 6 tall fescue (Fescue arundinacea Schreb.) cultivars were grown in greenhouse pots containing 1.0 kg of Altoxic Tatum soil (clayey, mixed, thermic, typic, Hapludult) at two pH levels (pH 4.6 and 5.7 for bluegrasses and pH 4.3 and 5.7 for fescues). Relative top yields (pH 4.6/pH 5.7)% of Kentucky bluegrass cultivars ranged from 8.0% for ‘Windsor’ to 91.0% for ‘Fylking’; relative root yields ranged from 5.3% for ‘Kenblue’ to 101.8% for ‘Victa’. Relative top yields (pH 4.3/pH 5.7)% of fineleaf fescues ranged from 17.1% for common creeping to 91.1% for ‘Wintergreen’; however, 11 of the 15 cultivars studied made satisfactory growth at pH 4.3. Relative top yields (pH 4.3/pH 5.7)% of the tall fescues ranged from 1.8% for ‘Fawn’ to 35.4% for ‘Kentucky 31’. Within several tall fescue cultivars, individual plants (in the same pot of unlimed soil at pH 4.3) showed wide growth differences which were largely equalized by liming the soil to pH 5.7. Results of our studies suggest appreciable potential for selecting or developing turfgrass cultivars for greater tolerance to acid soil stress factors (particularly Al toxicity) that may not be economically correctable. Such cultivars would be deeper rooted and better adapted to low maintenance conditions.