Tolerance of Eastern Gamagrass to Excess Aluminum in Acid Soil and Nutrient Solution

Authors

C. D. Foy, Climate Stress Laboratory, NRI, ARS, United States Department of Agriculture, Beltsville, MD

Date of this Version

1997

Citation

JOURNAL OF PLANT NUTRITION, 20(9), 1119-1136 (1997)

Comments

U.S. Government Work

Abstract

Eastern gamagrass, Tripsacum dactyloides L., has been reported to tolerate a wide variety of soil conditions, including drought, flooding, and acidity, but its specific tolerance to aluminum (Al) has not been tested. One strain of this species, PMK Select Lot 94 SFG-1, was tested for its tolerance to excess Al in an acid, Al-toxic Tatum subsoil (clayey, mixed, thermic, Typic Hapludult) and in nutrient solutions containing Al. Roots were able to penetrate unfertilized Tatum subsoil at pH levels as low as 4.1-4.2 (1:1 soil-water), at Al saturations of 64 to 77% of CEC, and to tolerate Al concentrations in nutrient solution that would be lethal for many crop plants. For example, with 4 mg Al L^-1 and a final solution pH of 4.67, shoot and root dry weights were 75 and 76%, respectively, of those with no Al. Even with 24 mg Al L^-1 and a final solution pH of 4.13, shoot and root dry weights were 45 and 46%, respectively, of those for the no Al check treatment. Hence, this strain of gamagrass shows promise for use on soils having acidic, Al-toxic subsoil layers that act as root barriers and predispose plants to injury by drought. Roots of gamagrass are also reported to penetrate hard clay pans and to create root channels for subsequent crops that lack this ability. Current studies indicate that the strain tested was susceptible to a chlorosis resembling iron (Fe) deficiency when grown in a Jiffy Mix potting mixture or with excess Al in nutrient solutions. Hence, gamagrass is tentatively being classified as a calcifuge [Al tolerant-Fe-inefficient]. In the current experiment, considerable plant to plant variability was noted regarding susceptibility to this chlorosis factor and to a purpling symptom resembling phosphorus (P) deficiency. Results indicate that an exhaustive screening of gamagrass populations could identify strains that are more suitable for specific soil situations.