Institute of Soil and Environmental Sciences, University of Agriculture, 38040 Faisalabad, Pakistan; Nuclear Institute for Agriculture and Biology (NIAB), P. O. Box 128, Jhang Road, Faisalabad, Pakistan.
Institute of Soil and Environmental Sciences, University of Agriculture, 38040 Faisalabad, Pakistan; Department of Environmental Health, College of Public Health, Imam Abdulrahman University, Dammam, Saudi Arabia.
Environ Pollut. 2018 Nov;242(Pt A):126-135. doi: 10.1016/j.envpol.2018.06.069. Epub 2018 Jun 26.
Given that cadmium (Cd) uptake by plants is linked to transpiration rate and activity of antioxidant enzymes and further that silicon (Si) can regulate them, it was hypothesized that improved Si nutrition could reduce Cd concentration in plants. Thus, present study was carried out to elucidate the positive effect of Si nutrition on the growth, activities of antioxidant enzymes and tissue cadmium (Cd) concentration in Cd-tolerant (Iqbal-2000) and Cd-sensitive wheat (Triticum aestivum L.) cultivars. Fifteen days after seedling transplantation, 15 μM Cd stress alone and in combination with 0.6 mM Si was applied. Silicon application improved root and shoot dry matter of Cd-sensitive cultivar Sehar-2006 while the effect was non-significant in Cd-tolerant cultivar Iqbal-2000. Silicon-treated Cd-sensitive cultivar showed marked improvements in chlorophyll content and photosynthesis, while stomatal conductance and transpiration rate decreased by Si application. Silicon treatment enhanced the activities of enzymatic antioxidants including catalase, ascorbate peroxidase, guaiacol peroxidase and superoxide dismutase and the increase was higher for Cd-tolerant cultivar Iqbal-2000. Although Si nutrition depressed malondialdehyde (MDA) content in both Cd-stressed cultivars, the response was more evident in Cd-sensitive Sehar-2006. Lower lipid peroxidation was related to Si-induced increase in antioxidant activities only in Cd-sensitive cultivar. Silicon application decreased Cd accumulation in the roots and shoots of both the cultivars. The decrease in shoot Cd was associated with a decrease in Cd uptake by roots and Cd translocation from roots to shoots. Overall, it is concluded that Si suppressed Cd contents by decreasing transpiration rate in Cd-sensitive cultivar and by increasing antioxidant activity in Cd-tolerant cultivar.
鉴于植物对镉（Cd）的吸收与蒸腾速率和抗氧化酶的活性有关，而硅（Si）可以调节这些酶的活性，因此假设改善 Si 营养可以降低植物中的 Cd 浓度。因此，本研究旨在阐明 Si 营养对 Cd 耐受（Iqbal-2000）和 Cd 敏感（Triticum aestivum L.）小麦品种生长、抗氧化酶活性和组织 Cd 浓度的积极影响。在幼苗移栽后 15 天，单独和同时施加 15 μM Cd 胁迫和 0.6 mM Si。Si 处理提高了 Cd 敏感品种 Sehar-2006 的根和地上部干物质含量，而对 Cd 耐受品种 Iqbal-2000 的影响不显著。Si 处理显著提高了 Cd 敏感品种的叶绿素含量和光合作用，而气孔导度和蒸腾速率则因 Si 处理而降低。Si 处理增强了包括过氧化氢酶、抗坏血酸过氧化物酶、愈创木酚过氧化物酶和超氧化物歧化酶在内的酶抗氧化剂的活性，对 Cd 耐受品种 Iqbal-2000 的增加更为明显。尽管 Si 营养降低了两种 Cd 胁迫品种的丙二醛（MDA）含量，但在 Cd 敏感的 Sehar-2006 品种中响应更为明显。较低的脂质过氧化与 Si 诱导的抗氧化活性增加有关，仅在 Cd 敏感品种中。Si 处理降低了两种品种根和地上部的 Cd 积累。地上部 Cd 的减少与根对 Cd 的吸收减少和 Cd 从根向地上部的转运减少有关。总的来说，结论是 Si 通过降低 Cd 敏感品种的蒸腾速率和增加 Cd 耐受品种的抗氧化活性来降低 Cd 含量。
