許多研究表明，土壤和沉積腐殖酸對石灰性土壤中種植的植物生長的有益作用與它們改善鐵植物營養(yǎng)的能力之間存在密切關系。這些結果歸因于腐殖酸（HA）改善鐵溶解度和生物利用度的能力。然而，不能排除與腐殖酸對缺鐵植物根系中激活的特定機制的作用有關的其他影響。雖然這個問題已經在雙子葉植物中進行了研究，但在禾本科植物中還沒有具體的研究。在這里，我們研究了從泥炭中提取的腐殖酸（HA）在鐵缺乏和充足的條件下提高小麥植株鐵營養(yǎng)的能力。結果表明，HA可以改善缺鐵小麥植株的生理狀態(tài)，減輕缺鐵對植株發(fā)育的一些有害影響，并提高植株向營養(yǎng)液分泌植物鐵載體的能力。HA的這種作用與葉片中鐵活性池的增加有關，這可能與HA與營養(yǎng)液中的植物鐵載體相互作用所產生的鐵絡合物的動員有關。反式玉米素核糖苷（tZR）的作用可能有利于鐵從根向地上部的轉移，因為在缺鐵植物中，HA提高了這種植物激素的葉片濃度。

Humic Acid Alleviates Fe Chlorosis in Graminaceous Plants Through Coordinated Fe-Dependent and Fe-Independent Mechanisms

Many studies have shown the close relationship between the beneficial action of soil and sedimentary humic acids on the growth of plants c*ted in calcareous soils and their ability to improve Fe plant nutrition. These results have been ascribed to the humic acid (HA) capability to improve Fe solubility and bioavailability. However, other effects more related to a humic acid action on the specific mechanisms activated in roots of plants under Fe deficiency cannot be ruled out. Although this question has been studied in dicotyledonous plants, in graminaceous plants there are no specific studies. Here we investigate the ability of a humic acid extracted from peat (HA) to improve Fe nutrition in wheat plants c*ted under Fe deficient and sufficient conditions. The results show that HA can improve the physiological status of Fe deficient wheat plants by alleviating some of the deleterious consequences of Fe deficiency on plant development and increasing the plant ability to secrete phytosiderophores to the nutrient solution. This action of HA is associated with increases in the Fe-active pool in leaves that might be related to the mobilization of the Fe complexed by HA resulting from the interaction of HA with the phytosiderophores in the nutrient solution. The Fe translocation from the root to the shoot may be favored by the action of trans-Zeatin Riboside (tZR) since the leaf concentration of this phytohormone was enhanced by HA in Fe deficient plants.

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