Phytoremediation technology is regarded as a simple and efficient way to remove heavy metals from contaminated soil. A reasonable disposal of metal hyperaccumulators is always a major issue in waste reuse and resource-saving. The heavy metal-accumulating Cynondon dactylon (L.) was investigated where heavy metals were desorbed by a facile acid-treatment. The result indicated that more than 90% of heavy metals (Zn, Pb and Cu) was extracted from Cynondon dactylon with 0.2 mmol ·L −1 HCl. The plant residue was used to adsorb heavy metals ions. The adsorption fitted the Langmuir isotherm model with the saturation adsorption capacity of 9.5 mg ·g −1 Zn 2+ , 36.2 mg·g −1 Pb 2+ and 12.9 mg·g −1 Cu 2+ , and the surface complexation and the backfilling of heavy metal-imprinting cavities existed simultaneously during the adsorption. The treatment of wastewaters indicated that the plant residue exhibited a high removal rate of 97% for Cu. Also, the material could be recycled. The method offers a new disposal approach for heavy metal hyper-accumulator.
Tian Hao,Zhimin Yang,Jianfeng Liang,Jingjin Yu,Jun Liu
Drought stress is one of the crucial factors affecting plant growth and development in turfgrass species, especially during the summer season. Exogenous plant growth regulators are an effective and convenient approach to mitigating the adverse effects of drought stress on plant growth. The objectives of this study were to reveal the effects of exogenous carnosine or chitosan on turf performance and physiological indexes in bermudagrass (Cynodon transvaalensis×C. dactylon) in response to drought stress. Bermudagrass was foliar sprayed with carnosine or chitosan, and dose-dependent effects on turf quality were observed under drought stress. Under drought stress, foliar application of either carnosine (0.03%) or chitosan (10 mg L−1) significantly increased turf quality, chlorophyll content, leaf relative water content, and decreased electrolyte leakage, malonaldehyde, and hydrogen peroxide content in comparison with untreated control in bermudagrass. Moreover, exogenous carnosine treatment significantly enhanced the activities of both catalase and peroxidase, but chitosan application only increased catalase activity. The results of this experiment were beneficial to the development of new plant growth regulators and would provide helpful insights for turf management under drought-stressed conditions.Keywords:bermudagrass;drought stress;carnosine;chitosan;antioxidant enzymes
Herbicide resistance or tolerance in weeds mediated by cytochrome P450 monooxygenase is a considerable problem. However, cytochrome P450 mediated resistance or tolerance in weeds was less studied. Thus, in this work, the role of the cytochrome P450 monooxygenase in the different responses of Poa annua and Alopecurus aequalis to fenoxaprop-P-ethyl was studied. We found that the effect of fenoxaprop-P-ethyl could be synergized by piperonyl butoxide (PBO) in P. annua , but not by malathion. After being treated with fenoxaprop-P-ethyl (containing mefenpyr-diethyl), the contents of cytochrome P450 and cytochrome b 5 in P. annua increased significantly compared to plants treated with mefenpyr-diethyl only or untreated plants. However, the increase was less in A. aequalis , which was susceptible to fenoxaprop-P-ethyl. The activities of ρ-nitroanisole O-demethylase (PNOD), ethoxyresorufin O-deethylase (EROD), ethoxycoumarin oxidase (ECOD) and NADPH-dependent cytochrome P450 reductase mediated by cytochrome P450 monooxygenase increased in P. annua after treatment with fenoxaprop-P-ethyl, especially the activities of ECOD and cytochrome P450 reductase. Besides this, cytochrome P450 monooxygenase activity toward fenoxaprop-P-ethyl in P. annua increased significantly compared to untreated or treated with mefenpyr-diethyl plants and treated or untreated A. aequalis . Cytochrome P450 monooxygenase may play an important role in the different responses to fenoxaprop-P-ethyl in P. annua and A. aequalis .
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