Effects of cadmium on the uptake,distribution and assimilation of nitrate in Pisum sativum |
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Authors: | Hernández L.E. Gárate A. Carpena-Ruiz R. |
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Affiliation: | (1) Departamento de Química Agrí, Geología y Geoquímica, Facultad de Ciencias, Universidad Autónoma de Madrid, Canto Blanco, E-28049 Madrid, Spain |
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Abstract: | The net uptake, distribution and assimilation of NO3– were studied in pea plants subjected to either long-term continuous Cd treatment for 10 d (10 or 50 M Cd) or short-term treatment (72 h) with 50 M Cd. In the latter treatment, the effects of transferring the plants to a Cd-free nutrient solution for a 'recovery period' of 96 h were also studied. All these treatments were compared with 'controls', plants which received no Cd. In both experiments, the reduction in fresh weight was associated with a decrease in the content (%) of shoot and root water and in transpiration rate as Cd concentration increased. The concentration of 3– in the shoots and sap decreased dramatically and net 3– uptake was severely inhibited, effects associated with a loss of shoot nitrate reductase (NR) activity. In the short-term Cd treatment, net 3– uptake was almost completely inhibited after 24 h, but recovered after the transfer of plants to a Cd-free nutrient solution. Similarly, a dramatic decrease in the shoot NR activity was observed. The uptake, distribution and tissue partitioning of K was also studied, which is considered to be the major counterion of 3–. Potassium uptake was similarly affected by Cd, as inferred from the ratio 3–/K uptake, which was ca. 10. The ratio K/3– tissue content increased in the shoot concomitantly to Cd in both long-term and short-term metal supply. These parameters showed a tendency of K similar to that observed for 3–, although its relative tissue distribution was not affected by Cd. |
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Keywords: | assimilation cadmium distribution nitrate Pisum sativum uptake |
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