Genetic Variation within Switchgrass Populations for Acid Soil Tolerance

Abstract

Tolerance to acid soil would be a desirable trait for switchgrass (Panicum virgatum L.) cultivars that are to be grown across the southern Great Plains. The objeclives of this research were to estimate genetic variation for, and examine the level of, acid soil tolerance at the seedling stage within two switchgrass populations. Seedlings of ‘Kanlow’ and ‘Blackwell’ were grown during 1993 and 1994 in acid soils (pH 3.9–5.0) in the greenhouse and harvesled 7 to 8 wk after planting. Seedlings were allowed to regrow and planted in polycross field isolation where half‐sib seed was produced. Progeny families were grown during 1995 and 1996 in acid soils (pH 4.4–5.1) in the greenhouse, and seedling shoot weight data collected 7 to 8 wk after planting. Heritability (h2) for weight of seedlings grown in acid soil was estimated by parent‐progeny regression. Growth ofhalf‐sib families in a limed and non‐limed acid soil was also examined. Estimates of h2 were low or non‐significant, ranging from 0.18 ± 0.08 to 0.06 ± 0.02 for Kanlow and 0.06 ± 0.02 for Blackwell. The low h2 estimates, coupled with a lack of significant variation for seedling shoot weight among families grown in acid soil, indicate little or no genetic variation for acid soil tolerance among seedlings of Blackwell or Kanlow. Seedling weight of half‐sib families grown in a soil limed to near‐neutral pH was not significantly different from seedling weight of the identical families grown in an acidic soil. Thus, at the seedling stage Kanlow and Blackweil switchgrass appear to have substantial tolerance to acid soil.