科研之友
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摘要
Hydroponic culture experiments were conducted to find out the changes of rice root morphological characteristics and root exudates after single and combined pollutants treatments of tetracycline (TC) and cadmium (Cd). Pollutants accumulation in rice roots at tillering stage has been studied, so as to elucidate the mechanism of antibiotic and heavy metal combined pollution on rice root system. In single pollutant treatment of TC or Cd, both root biomass and chlorophyll content decreased, which indicated adverse effects on rice growth. However, antagonism effect was observed at low dose TC and Cd combined pollutants treatment. The root elongation and transpiration rate of rice plants showed promotion in low concentration exposure of single or combined pollutants treatments while high concentration exposure environment limited various physiological indexes. The accumulation of TC or Cd in rice root showed observable increase with the increase of the concentration of TC and Cd. Moreover, the coexistence of TC and Cd could increase the bioavailability and affinity of both pollutants, which results in synergistically promotion of pollutants accumulation in rice root. However, high TC concentration might led to Cd accumulation reduction in rice root because of complexation enhancement. The secretion of rice root exudates was significantly inhibited under single pollutant treatment of TC or Cd, but the combined pollution treatment showed different effects. In combined TC and Cd at low concentration treatment, with the remission of toxicity, the increased rice root exudates may result from increased photosynthesis rate and transpiration rate. But, the integrity of rice root cells was damaged under high concentration treatment, which inhibited the secretion of root exudates. Further analysis showed that the secretion of amino acids and derivatives, organic acids and sugar alcohols in root exudates increased significantly under high concentration combined pollutant treatment. The complexation of TC and Cd decreased the bioavailability of Cd, and alleviated the toxicity of Cd under high concentration treatment on rice, which increased the secretion of organic acids, amino acids and derivatives and sugar alcohols for detoxication. The results of this study can provide reference data for ensuring the safe production of rice and establishing effective rhizosphere regulation measurement for the control of antibiotic-heavy metal combined pollution. ? 2021, Science Press. All right reserved.
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