Developing aluminum‐tolerant strains of tall fescue for acid soils

Publisher Website
Google Scholar
Abstract
Tall fescue (Festuca arundinacea Schreb.) is an important cool season perennial grass used for forage and turf. It is reportedly more tolerant to acid soils than Kentucky bluegrass (Poa pratensis L.) but less tolerant than the fine leafed fescues. In previous studies, Kentucky 31 was the most acid soil tolerant cultivar tested on aluminum (Al)‐toxic Tatum subsoil at pH 4.3. However, a few plants within several cultivars showed high tolerance to this acid soil. This suggested the potential for increasing acid soil (Al) tolerance by selection within established cultivars. Aluminum‐tolerant cultivars are needed for use on marginal soils having acid (pH 0), relative dry weights were increased by 99% for shoots and 111% for roots. Increases in acid soil tolerance were more pronounced in derivatives of Ky‐31 and turf‐type than in those of Alta fescue. When plants were grown in nutrient solutions, recurrent acid soil selections of Ky‐31 and turf‐type fescues showed increased overall plant vigor and Al tolerance, but those of Alta fescue did not. Recurrent acid soil selection was more effective in increasing acid soil tolerance per se than in increasing Al tolerance in nutrient solutions. Increased acid soil (Al) tolerance in the first and second cycle selections in the Ky‐31 cultivar was associated with greater plant‐induced pH increases in nutrient solutions than those produced by the parent cultivar. A lower pH in solution means that the parent Ky‐31 cultivar was exposed to higher concentrations of soluble Al than were its derivatives. Results indicated that established cultivars of tall fescue contain considerable genetic variation with respect to acid soil tolerance and that recurrent selection can be used to identify genotypes that are better adapted to acid marginal soils that are frequently used in low level management systems for forage or turf. During a severe drought, a field plot of KpH2 remained green 10 days longer than that of the parent cultivar Ky‐31. Hence, acid soil (Al) tolerance coincided with drought tolerance.