Photosynthetic Response of Maize Plants Against Cadmium and Paraquat Impact

• Published in: Water, air, and soil pollution air, and soil pollution, 2010-05, Vol.208 (1-4), p.287-293
• Main Authors: Chaneva, Ganka, Parvanova, Petya, Tzvetkova, Nikolina, Uzunova, Alexandra
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Atmospheric Protection/Air Quality Control/Air Pollution; Biological and medical sciences; Cadmium; Carbon dioxide; Carotenoids; Chlorophyll; Climate Change/Climate Change Impacts; Conductance; Corn; Corn industry; Crops; Earth and Environmental Science; Ecotoxicology, biological effects of pollution; Environment; Environmental monitoring; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gas exchange; General aspects; Growth rate; heavy metals; Herbicides; Hydrogeology; Hydroponics; Leaves; metabolic inhibitors; Paraquat; Photosynthesis; physiological response; Phytochemistry; pollutants; Pollution; Soil contamination; Soil pollution; Soil Science & Conservation; Spraying; Stomata; Stomatal conductance; Studies; Toxicity; Transpiration; Variance analysis; Water Quality/Water Pollution; Zea mays
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-009-0166-x

The effects of cadmium (Cd) and/or paraquat (PQ) toxicity on photosynthesis in maize leaves were examined by measurement of gas exchange and chlorophyll content in hydroponically cultured plants. It was found that growth rate was distinctly influenced only by 100 µM Cd treatment. Chlorophyll a and chlorophyll b decreased along with the increase of Cd concentration, while PQ spraying, alone and combined with Cd, increased chlorophyll a content on the third and seventh experimental days. Generally, carotenoid content increased in response to Cd and PQ and reached the highest levels at 100 µM Cd. Rate of photosynthesis in maize decreased after Cd treatment. CO₂ assimilation was approximately 60% reduced at 50 µM Cd and 70% reduced in the presence of 100 µM Cd. PQ toxicity was partly overcome after the third day of exposure. Transpiration and stomatal conductance in maize leaves decreased on the third day along with Cd concentration and PQ spraying, except for the 25-µM Cd-treated plants. On the tenth day, the 25-µM Cd-treated plants and those from PQ-treated variants showed an increase of transpiration and stomatal conductance. Maize exhibited an ability to accumulate Cd in high quantities, especially in the roots—over 4,500 mg Cd/kg dry weight.