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PW03 Plant Toxicology and Soil Interactions
(PW065) The effects of low level cadmium toxicity on field and greenhouse grown soybean (Glycine max).
Walley, J1, Huerta, A1, 1 Miami University, Oxford, OH, USA
ABSTRACT- This study was conducted to examine the physiological effect of agriculturally relevant levels of cadmium on field and greenhouse grown soybean (Glycine max). Numerous studies pertaining to cadmium toxicity have been conducted using high levels of cadmium for short periods of time representing acute exposure. In addition, many of the studies have been preformed using isolated chloroplasts, excised plant tissue or hydroponically grown plants. However, relatively few experiments investigating physiological effects have been performed on plants grown on soils polluted with cadmium at concentrations of environmental relevance. The levels of cadmium that plants are typically exposed to in nature are lower and present for the duration of the plants life. Cadmium levels of 0, 2.5, 5, and 10 micro g Cd/g dry wgt soil were selected. The cadmium levels used represent environmentally relevant concentrations and the upper levels have been reported to result in a 25 to 50% growth reduction. Measurements of stomatal conductance, instantaneous transpiration, sap flow (real-time transpiration), net photosynthetic rate, carbon assimilation response to leaf internal CO2 concentration, chlorophyll fluorescence, growth parameters and cadmium levels in leaf and soil were conducted throughout the soybeans life span. Physiological and growth measurements did not show a significant difference between the control and cadmium treatments in either field or greenhouse grown soybeans. Plant available cadmium levels in the soil were measured 2.5 and 4 months following planting and found to be 8 and 3.7 micro g Cd/g dry wgt soil, respectively. This indicates that the lack of significant difference between control and treatment plants for the physiological and growth data is not due to a lack of cadmium available in the soil.
Key words: photosynthesis, cadmium, physiology
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