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| Allelopathic effects of alkaloids in Mirabilis jalapa L. under cadmium stress |
| Received:January 28, 2022 Revised:April 18, 2022 |
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| KeyWord:cadmium;Mirabilis jalapa L.;root exudate;alkaloid;allelopathic effect |
| Author Name | Affiliation | E-mail | | HU Yan | Faculty of Environmental Science and Engineering, Kunming University of Science and Technology/Yunnan Key Lab of Soil Carbon Sequestration and Pollution Control, Kunming 650500, China | | | WANG Haijuan | Faculty of Environmental Science and Engineering, Kunming University of Science and Technology/Yunnan Key Lab of Soil Carbon Sequestration and Pollution Control, Kunming 650500, China | | | WANG Hongbin | Faculty of Environmental Science and Engineering, Kunming University of Science and Technology/Yunnan Key Lab of Soil Carbon Sequestration and Pollution Control, Kunming 650500, China | whb1974@126.com |
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| Abstract: |
| To investigate the allelopathic effects of alkaloids in M. jalapa on native species under Cd stress, hydroponic and pot experiments, combined with ultra-performance liquid chromatography（UPLC） , were conducted to determine the content of alkaloids in root exudates of M. jalapa exposed to Cd. The effects of root exudates, exogenous alkaloids, and rhizospheric soil on seed germination and seedling growth of two native species（radish and lettuce）were investigated, showing that under hydroponic conditions, the contents of trigonelline, berberine, and palmatine in root exudates of M. jalapa under 1-3 mg·L-1 Cd stress were significantly increased. Under the stress of 3 mg·L-1 Cd, the root exudates had the strongest inhibitory effect on seed germination and seedling growth in radish and lettuce, with inhibition rates of 25.17% and 44.23% in seed germination and root length in radish, respectively, and of 10.00% and 40.44%, respectively, in lettuce. The inhibitory effect of root exudate from radish was higher than that from lettuce. The allelopathic effects of the exogenous alkaloids on the seedling growth of radish and lettuce were different. The lowest inhibitory concentrations of berberine were 0.1 mg·L-1 and 0.05 mg·L-1, showing the highest allelopathic effect. Palmatine and rhizobine showed a moderate allelopathic effect, with a minimum inhibitory concentration of 0.25 mg·L-1. The weakest allelopathic effect was observed for trigonelline, with minimum inhibitory concentrations of 100 mg·L-1 and 50 mg·L-1. The allelopathic effect of M. jalapa-growing soil under Cd stress also differed between nonsterile and sterile soils. Except for 25 mg·kg-1 Cd stress, the non-sterile soil promoted seed germination and seedling growth of radish and lettuce to different degrees, and lettuce showed better promotion. However, an inhibitory effect was observed in sterile soil. Under a stress of 5 mg·kg-1 Cd, the maximum inhibition rates of seed germination and seedling growth in radish were 41.23% and 48.54%, respectively, and those in lettuce were 21.07% and 15.25%, respectively. Our results indicated that under Cd stress conditions, the allelopathic effects of M. jalapa on the local species in hydroponic and pot experiments differed, and soil culture and non-sterile conditions mitigated the allelopathic effects of alkaloids. Moreover, lettuce is a suitable species for intercropping with M. jalapa for the remediation of Cd-polluted agricultural soil owing to its low allelopathic inhibition. |
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