EVALUATION OF SWITCHGRASS ENTRIES FOR ACID SOIL TOLERANCE

Crop and forage yields are significantly reduced by strong soil acidity throughout much of the northeastern United States. Switchgrass (Panicum virgatum L.) is a valuable perennial warm-season pasture species generally regarded as tolerant to stress conditions, i.e., infertile, dry, or low pH soils; however, switchgrass has not been studied for variability in acid soil tolerance. The objectives of this study were (a) to compare the responses of different switchgrass entries to soil acidity, and (b) to identify selected agribotanical trait response to unlimed (-L) and limed (+L) soil. Sixteen entries (cultivars, germplasms, and breeding populations) were studied in short- and meso-term experiments. Unlimed (pH 4.9) and limed (pH 5.9) treatments of a sandy loam soil (Typic Dystrochrept) were used in both experiments. Switchgrass seedlings were exceptionally tolerant of soil acidity in the short-term experiment. In the meso-term experiment, acid soil stress significantly reduced all agribotanical traits (plant height, leaf area, top weight, and root weight) determined in the study when compared to +L plants. There were significant, positive correlations among the agribotanical traits; however, the effect of -L soil was more obvious on root weight and less so on plant height. Entries 922 GST6, 920 AST6, 921 DST6, and 922 BST6 showed superior general adaptability and promising forage production, while cultivars Carthage and PI 142138 were acid soil tolerant with low productivity. Our data suggests that selection for increased acid soil tolerance in switchgrass may be possible and would result in improved productivity of this grass in acid soil environments.