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| DOI：10.13522/j.cnki.ggps.2020141 |
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| Effects of Cadmium Stress on Cadmium Uptake Accumulation and Photosynthetic Characteristics of Pumpkin |
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CHEN Bihua, GUO Weili, MENG Fanru, ZHOU Junguo, LI Xinzheng, SHEN Ke
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1. School of Horticulture and Landscape Architecture, Henan Institute of Science and Technology, Xinxiang 453003, China;2. Xinxiang Muye District Bureau of Agriculture and Rural Affairs, Xinxiang 453003, China
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| Abstract: |
| Heavy metal cadmium (Cd) pollution has become one of the hot issues, when Cd enters the tissues and cells of the plant, it interferes with the normal physiological metabolism of the cell, destroys the chlorophyll and transpiration effects of the plant, and causes growth disorder or even death. Pumpkin is one of the cadmium-resistant rootstocks commonly used for cucurbitacae vegetables.【Objective】We aimed to study the absorption and accumulation characteristics of cadmium in pumpkin plants and the effect of cadmium stress on photosynthetic characteristics of pumpkin leaves, further revealing the accumulation characteristics and toxicity mechanism of pumpkin on heavy metal cadmium, provide a scientific basis for the screening of cucumber cadmium-resistant rootstocks in greenhouses. 【Method】Using microwave digestion-ICP-AES technology and the Chinese pumpkin “Yanzhen 1” as experimental material, we set up 4 treatments, and added different amounts of Cd (added in the form of CdSO4): 0, 2, 4, 6 mg/L, each treatment repeated 4 times, and each plastic small black square pot (7 cm caliber) was assembled with 0.000 27 m3 substrate. The sprouted pumpkin seeds are sown in the substrate, and the film is kept warm and moisturized. When the two cotyledons of the seed emerged and the true leaves were exposed, we added different concentrations of Cd into the pots and used a pipette to pour 10 mL Cd solution near the root of the plant every 5 days for a total of 4 times. Pumpkin plants were divided into roots, stems and leaves, washed and dried separately. In order to remove the Cd adsorbed on the surface of the pumpkin root, the pumpkin root was first rinsed with deionized water, and then treated with 20 mmol/L Na2-EDTA exchange for 20 min, then washed with deionized water, and absorbed the surface moisture. Fresh plant samples were kept in the -20 ℃ refrigerator for future use. The photosynthetic parameters of leaves, the sub-cellular distribution of Cd and the distribution of organs (roots, stems and leaves) were determined.【Result】The content of Cd in pumpkin root increased much more than that of stem and leaf. With the increase of Cd concentration, the BCF of root increased and the TF decreased gradually. Cd was unevenly distributed among the subcellular components of different organs. The distribution rate of cell wall in roots was up to 47.63%~57.69%, followed by cytoplasm; and the Cd content in organelles only accounted for 1.93%~4.59%. Cd treatment did not significantly inhibit the net photosynthetic rate (Pn) of pumpkin, while Cd treatment significantly inhibited stomatal conductance (Gs) and transpiration rate (Tr), but there was no significant difference in intercellular CO2 concentration (Ci) between Cd treatments. 【Conclusion】The cell wall in the root system of “Yanzhen 1” pumpkin plant has a strong ability to accumulate Cd, while the accumulation of the remaining components is relatively reduced, which restricts the transportation and accumulation of Cd to the above ground. With the increase of Cd concentration, Cd transfers from the root to stem and leaves gradually decreased, but Cd stress did not cause significant inhibition on photosynthesis. |
| Key words: cadmium stress; pumpkin; subcellular distribution; photosynthetic; enrichment coefficient; transfer coefficient |
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