|Reed, R - TEXAS A&M UNIVERSITY|
|Allen, V - TEXAS TECH UNIVERSITY|
|Matches, A - TEXAS TECH UNIVERSITY|
Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 22, 1999
Publication Date: October 22, 1999
Citation: Reed, R.L., Sanderson, M.A. 1999. Growth and cadmium accumulation in selected switchgrass cultivars. Communications in Soil Science and Plant Analysis. 30:2655-2667. Interpretive Summary: Use of switchgrass as a biofuels crop includes the input of fertilizer nutrients into the production system. Because the use of commercial fertilizer entails significant economic costs and the use of fossil fuels in their manufacture, alternate sources of fertilizer nutrients are needed. Municipal sewage sludge could be used to provide an economical source of nutrients. Long-term application of sludge, however, may lead to increase levels of heavy metals (such as cadmium) in the soil. Because the use of switchgrass as a biofuels crop is a nonfood chain use, exposure to heavy metals may be of lesser concern than for food chain crops. We conducted greenhouse tests to determine if switchgrass varieties differed in their response to cadmium. Yields of four switchgrass varieties were decreased by one-third when grown at high cadmium levels in nutrient solution. Roots were not affected as much as shoots. Switchgrass is tolerant of high levels of cadmium, but cadmium levels in the forage were above the suggested maximum tolerance levels. Switchgrass can be grown on cadmium- contaminated soil to produce acceptable yields; however, the forage should not be used as an animal feed without testing and verification of cadmium concentration. Varieties differ in their cadmium concentration; therefore, selection for cadmium accumulation within switchgrass may be possible.
Technical Abstract: Switchgrass (Panicum virgatum L.) has potential as a biofuel crop. Using alternative sources of fertilizer nutrients could enhance production of switchgrass. Alternative sources of fertilizer, such as sewage sludge, sometimes contain heavy metals such as Cd and the response of switchgrass to Cd is not known. Four switchgrass cultivars (Alamo, Blackwell, Cave-in- -Rock, and Trailblazer) grown in sand culture were watered twice weekly wit a nutrient solution containing Cd. Cadmium levels in solution were 0, 1, 2, 4, 8, and 16 mg Cd L-1. Plants were harvested 63 d after planting and separated into leaf blade, stem, and roots. Tissue Cd concentrations were determined using atomic absorption spectrophotometry. Cultivars differed (P < 0.05) by less than 15% for biomass accumulation and allocation among plant parts. Cadmium levels of 16 mg L-1 reduced biomass yields by 31% for roots, 39% for leaf blades, and 47% for stems as compared to no added Cd. At 16 mg Cd L-1, Cd concentration in leaf blades was 9.9 mg kg-1. The highest levels of Cd (329 mg kg-1) were found in roots of Blackwell and Trailblazer grown at the highest Cd level. Cadmium at 16 mg Cd L-1 is phytotoxic to switchgrass and accumulates in all plant parts. The cultivars tested in this study did not differ in biomass accumulation in response to Cd; however, Cd accumulation in plant parts differed among cultivars. Consideration of Cd uptake should be a part of switchgrass cultivar selection when grown in the presence of Cd.