College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
Key Laboratory of Tropical Agricultural Environment in South China, Ministry of Agriculture, Guangzhou 510642, China.
Ying Yong Sheng Tai Xue Bao. 2021 Mar;32(3):1096-1104. doi: 10.13287/j.1001-9332.202103.005.
Silicon (Si) application could significantly alleviate the toxic effects of cadmium (Cd) on the growth and development of rice. Here, we examined the regulatory effects of Si on Cd accumulation and stress response in rice seedlings through a hydroponic root separation test. The results showed that the biomass of rice seedlings decreased significantly under Cd stress, while the addition of Si could alleviate such negative effect. The uptake, transfer, and accumulation of Cd in rice seedling were significantly affected by Si addition under Cd stress. Si application under the unilateral Cd stress (Si-Cd+Si, Si-Cd) increased Cd-retention coefficient of root by 83.3%-83.6%, which restricted the transfer of Cd from root to aboveground. However, the treatment with Si added to the non-stressed side (Si-Cd) elevated the uptake and accumulation of Cd in rice seedling, with the accumulation in root being increased by 48.2% when compared to the treatment under the unilateral Cd stress without the addition of Si (CK-Cd). The treatment with Si added in two sides (Si-Cd+Si) decreased the uptake of Cd both in root and aboveground parts by 36.7% and 54.9%, respectively. The addition of Si under bilateral Cd stress (Cd-Cd+Si) significantly reduced the Cd uptake of both the root and aboveground parts by 57.8% and 46.5%, respectively, compared to the treatment of bilateral Cd stress (Cd-Cd). Higher Si concentration in rice seedling was found under the Cd stress. More Si was accumulated in rice seedling to resist the Cd stress when Si was added. The addition of Si affected the absorption of other metal elements in rice seedlings, including calcium (Ca), magnesium (Mg) and manganese (Mn). The concentrations of Ca and Mg in root and aboveground parts were significantly increased by Si addition under bilateral Cd-stress (Cd-Cd+Si), but Mn concentration was changed with the stress degree of Cd. The activities of superoxide dismutase (SOD) and peroxidase (POD) in root were affected by Si under Cd stress, especially for the Si-Cd treatment. The activity of POD in the root of the Cd-stress side and that of SOD in non-stress side were significantly increased, which benefit to scavenging the free radicals induced by Cd stress. In conclusion, Si could regulate the growth of rice seedlings, the uptake of elements such as Cd and Si, and the antioxidant reaction of the root system under the Cd stress. High Si concentration in plant is conducive to enhancing Cd tolerance.
硅（Si）的应用可以显著减轻镉（Cd）对水稻生长和发育的毒害作用。在这里，我们通过水培根分离试验研究了 Si 对水稻幼苗 Cd 积累和胁迫响应的调控作用。结果表明，Cd 胁迫下水稻幼苗生物量显著下降，而添加 Si 可减轻这种负效应。Si 对 Cd 胁迫下水稻幼苗 Cd 的吸收、转运和积累有显著影响。单侧 Cd 胁迫下（Si-Cd+Si、Si-Cd）添加 Si 可使根 Cd 保留系数增加 83.3%-83.6%，限制了 Cd 从根部向地上部的转运。然而，在非胁迫侧添加 Si（Si-Cd）的处理则增加了水稻幼苗对 Cd 的吸收和积累，与单侧 Cd 胁迫下不添加 Si（CK-Cd）相比，根部积累增加了 48.2%。双侧 Cd 胁迫下（Si-Cd+Si）添加 Si 分别使根和地上部 Cd 的吸收量减少 36.7%和 54.9%。双侧 Cd 胁迫下添加 Si（Cd-Cd+Si）与双侧 Cd 胁迫处理相比，根和地上部 Cd 吸收量分别减少 57.8%和 46.5%。在 Cd 胁迫下，水稻幼苗中 Si 浓度较高。当添加 Si 时，水稻幼苗中积累了更多的 Si，以抵抗 Cd 胁迫。Si 的添加影响了水稻幼苗对其他金属元素的吸收，包括钙（Ca）、镁（Mg）和锰（Mn）。双侧 Cd 胁迫下（Cd-Cd+Si）添加 Si 可显著增加根和地上部 Ca 和 Mg 的浓度，但 Mn 浓度随 Cd 胁迫程度而变化。Si 处理下，Cd 胁迫下根中超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性受到影响，尤其是 Si-Cd 处理。Cd 胁迫侧根 POD 活性和非胁迫侧 SOD 活性显著升高，有利于清除 Cd 胁迫诱导的自由基。总之，Si 可以调节水稻幼苗的生长、Cd 和 Si 等元素的吸收以及根系的抗氧化反应。植物中高浓度的 Si 有利于增强 Cd 耐受性。
