| heal.abstract |
Wetland plants possess various characteristics that enable them to survive oxygen deficiency. Putting forward the hypotheses that the pools of micronutrients may respond to short-term hypoxic and post-hypoxic fluctuations in their rhizosphere at the whole plant level, and that this response may alter with age, we examined for two years the effect of such conditions on the iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) pools of roots, stems, petioles, and leaves of the wetland Apium nodiflorum (Fool's watercress) young, mature, and aged plants (2, 6, and 10-month-old, respectively). Young and mature plants behaved almost in the same manner. Iron and Mn levels in the organs of plants experiencing hypoxia did not shift from the normoxic levels. In contrast, Zn and Cu levels increased under oxygen deficiency, but each nutrient presented different behavior. Copper increased in all organs of young and mature plants. Zinc increased only in leaves and roots of young and mature plants. Especially, the increase of Zn in roots was a tremendous one, 6 times above the normoxic levels. Such characteristic increases in Cu and Zn levels were not observed in aged leaves, and petioles. Zinc levels of aged roots almost doubled. Thus, there were alterations in the effect of oxygen deficiency on Zn and Cu homeostasis within A. nodiflorum aged organs, that is, when the plants enter their reproductive stage. The described deviations from normoxic levels may be useful as diagnostic indices of the situation. |
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