Zaheer Ihsan Elahi, Ali Shafaqat, Saleem Muhammad Hamzah, Ali Mohsin, Riaz Muhammad, Javed Sehar, Sehar Anam, Abbas Zohaib, Rizwan Muhammad, El-Sheikh Mohamed A, Alyemeni Mohammed Nasser
Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, Faisalabad, 38000 Pakistan.
Department of Biological Sciences and Technology, China Medical University, Taichung, 40402 Taiwan.
Physiol Mol Biol Plants. 2020 Dec;26(12):2435-2452. doi: 10.1007/s12298-020-00912-0. Epub 2020 Dec 2.
Untreated wastewater contains toxic amounts of heavy metals such as chromium (Cr), which poses a serious threat to the growth and physiology of plants when used in irrigation. Though, Cr is among the most widespread toxic trace elements found in agricultural soils due to various anthropogenic activities. To explore the interactive effects of micronutrients with amino acid chelators [iron-lysine (Fe-lys) and zinc-lysine (Zn-lys)], pot experiments were conducted in a controlled environment, using spinach ( L.) plant irrigated with tannery wastewater. . was treated without Fe and Zn-lys (0 mg/L Zn-lys and 0 mg/L Fe-lys) and also treated with various combinations of (interactive application) Fe and Zn-lys (10 mg/L Zn-lys and 5 mg/L Fe-lys), when cultivated at different levels [0 (control) 33, 66 and 100%) of tannery wastewater in the soil having a toxic level of Cr in it. According to the results, we have found that, high concentration of Cr in the soil significantly ( < 0.05) reduced plant height, fresh biomass of roots and leaves, dry biomass of roots and leaves, root length, number of leaves, leaf area, total chlorophyll contents, carotenoid contents, transpiration rate (E), stomatal conductance (gs), net photosynthesis (PN), and water use efficiency (WUE) and the contents of Zn and Fe in the plant organs without foliar application of Zn and Fe-lys. Moreover, phytotoxicity of Cr increased malondialdehyde (MDA) contents in the plant organs (roots and leaves), which induced oxidative damage in . manifested by the contents of hydrogen peroxide (HO) and membrane leakage. The negative effects of Cr toxicity could be overturned by Zn and Fe-lys application, which significantly ( < 0.05) increase plant growth, biomass, chlorophyll content, and gaseous exchange attributes by reducing oxidative stress (HO, MDA, EL) and increasing the activities of various antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) catalase (CAT) and ascorbate peroxidase (APX). Furthermore, the supplementation of Zn and Fe-lys increased the contents of essential nutrients (Fe and Zn) and decreased the content of Cr in all plant parts compared to the plants cultivated in tannery wastewater without application of Fe-lys. Taken together, foliar supplementation of Zn and Fe-lys alleviates Cr toxicity in . by increased morpho-physiological attributes of the plants, decreased Cr contents and increased micronutrients uptake by the soil, and can be an effective in heavy metal toxicity remedial approach for other crops.
未经处理的废水中含有有毒量的重金属，如铬（Cr），用于灌溉时会对植物的生长和生理构成严重威胁。然而，由于各种人为活动，铬是农业土壤中最普遍存在的有毒微量元素之一。为了探究微量营养素与氨基酸螯合剂[铁赖氨酸（Fe-lys）和锌赖氨酸（Zn-lys）]的交互作用，在可控环境下进行了盆栽试验，使用制革废水灌溉菠菜（L.）植株。在土壤中铬含量达到有毒水平的情况下，当以不同水平[0（对照）、33%、66%和100%]的制革废水进行培养时，一组植株不添加铁和锌赖氨酸（0 mg/L锌赖氨酸和0 mg/L铁赖氨酸）处理，另一组植株进行铁和锌赖氨酸的各种组合（交互施用）处理（10 mg/L锌赖氨酸和5 mg/L铁赖氨酸）。结果表明，在不进行叶面喷施锌和铁赖氨酸的情况下，土壤中高浓度的铬显著（P＜0.05）降低了株高、根和叶的鲜生物量、根和叶的干生物量、根长、叶片数、叶面积、总叶绿素含量、类胡萝卜素含量、蒸腾速率（E）、气孔导度（gs）、净光合速率（PN）和水分利用效率（WUE），以及植物器官中锌和铁的含量。此外，铬的植物毒性增加了植物器官（根和叶）中丙二醛（MDA）的含量，这导致了植物体内的氧化损伤，表现为过氧化氢（H₂O₂）含量和膜透性增加。施用锌和铁赖氨酸可以扭转铬毒性的负面影响，通过降低氧化应激（H₂O₂、MDA、EL）并提高超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）等各种抗氧化酶的活性，显著（P＜0.05）增加植物生长、生物量、叶绿素含量和气态交换特性。此外，与未施用铁赖氨酸而用制革废水培养的植物相比，锌和铁赖氨酸的补充增加了所有植物部位必需营养素（铁和锌）的含量，并降低了铬的含量。综上所述，叶面喷施锌和铁赖氨酸通过增加植物的形态生理特性、降低铬含量和增加土壤对微量营养素的吸收，减轻了菠菜中的铬毒性，并且可能是一种有效的其他作物重金属毒性修复方法。
