许多研究表明，土壤和沉积腐殖酸对石灰性土壤中种植的植物生长的有益作用与它们改善铁植物营养的能力之间存在密切关系。这些结果归因于腐殖酸（HA）改善铁溶解度和生物利用度的能力。然而，不能排除与腐殖酸对缺铁植物根系中激活的特定机制的作用有关的其他影响。虽然这个问题已经在双子叶植物中进行了研究，但在禾本科植物中还没有具体的研究。在这里，我们研究了从泥炭中提取的腐殖酸（HA）在铁缺乏和充足的条件下提高小麦植株铁营养的能力。结果表明，HA可以改善缺铁小麦植株的生理状态，减轻缺铁对植株发育的一些有害影响，并提高植株向营养液分泌植物铁载体的能力。HA的这种作用与叶片中铁活性池的增加有关，这可能与HA与营养液中的植物铁载体相互作用所产生的铁络合物的动员有关。反式玉米素核糖苷（tZR）的作用可能有利于铁从根向地上部的转移，因为在缺铁植物中，HA提高了这种植物激素的叶片浓度。
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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