施硅对镉胁迫下生育前期水稻生长及其植株体内抗氧化酶活性的影响

Effects of Silicon Application on Growth and Antioxidant System of Rice in the Pre- fertility Period under Cadmium Stress

    摘要
  • 摘要:
      目的  探究在北方水稻土中施硅对镉胁迫下水稻生长、光合特性以及抗氧化系统的影响，为进一步应用硅缓解水稻镉毒害提供理论依据。
      方法  通过盆栽试验方法，研究在不同浓度镉添加水平（0、1、3、5 mg kg−1）下，施加不同浓度的硅（0、100、300、500 mg kg−1）对生育前期（至分蘖期）水稻生长、叶片光合特性和抗氧化系统的影响。
      结果  不同浓度镉胁迫均显著降低了水稻株高、根长和生物量（地上部和根部鲜重），增加了水稻茎叶中镉含量，降低了水稻叶片叶绿素含量、净光合速率、胞间CO2和蒸腾速率。施镉量为3和5 mg kg−1时，水稻叶片气孔导度显著下降。镉胁迫下，施硅增加了水稻叶片叶绿素含量，降低了水稻茎叶中镉含量，改善了水稻叶片光合特性；水稻的株高、根长和生物量也随着硅的施入而得到提高。对于抗氧化系统来说，与空白对照（Si0Cd0）相比，施镉量为3和5 mg kg−1时，水稻叶片超氧化物歧化酶和过氧化氢酶活性显著降低、降幅达16.9%、26.3%和9.3%、15.7%，而过氧化物酶活性显著提高、提高幅度为51.1%和66.6%；镉胁迫使水稻叶片丙二醛和脯氨酸含量显著增加。与不施硅相比，在不同浓度镉胁迫下，施加100、300 mg kg−1的硅使水稻叶片超氧化物歧化酶和过氧化氢酶活性显著提高、升高幅度达20.4% ~ 58.9%、25.3% ~ 72.5%和5.8% ~ 11.9%、22.7% ~ 25.4%，过氧化物酶活性显著降低、降幅达21.2% ~ 43.0%和31.8% ~ 50.8%；同时，施加300和500 mg kg−1硅使水稻叶片丙二醛和脯氨酸含量均显著降低。
      结论  不同硅添加量对镉胁迫下生育前期水稻生长、叶片叶绿素含量及其光合特性、抗氧化系统的改善作用明显，且以添加300 mg kg−1硅处理的效果最好。

     

    Abstract:
      Objective  The aims were to explore the effects of Silicon (Si) application on growth, photosynthesis and antioxidant system of rice under Cadmium (Cd) stress in northern paddy soil, so as to provide a theoretical basis for further application of Si to alleviate Cd toxicity in rice.
      Method  Under different Cd addition levels (0, 1, 3 and 5 mg kg−1), the effects of different Si concentrations (0, 100, 300 and 500 mg kg−1) on rice growth, leaf photosynthesis and antioxidant system in the pre- fertility period (to tillering stage) were studied by using the pot experiment.
      Result   The rice plant height, root length and biomass (aboveground and root fresh weight), chlorophyll content, net photosynthetic rate (Pn), intercellular CO2 (Ci) and transpiration rate (Tr) in rice leaves were decreased significantly under different Cd concentrations, and the Cd content in rice shoot was increased. When the amounts of Cd applied were 3 and 5 mg kg−1, stomatal conductance (Gs) decreased significantly in rice leaves. Under Cd stress, Si application increased chlorophyll content and photosynthetic characteristics of rice leaves, decreased Cd content in rice shoot. The plant height, root length and biomass of rice were also increased with the application of Si. For the antioxidant system, compared with the blank control (Si0Cd0), when 3 and 5 mg kg−1 Cd was applied, SOD and CAT activities were significantly decreased by 16.9%, 26.3% and 9.3%, 15.7%, while POD activities were significantly increased by 51.1% and 66.6%. MDA and Pro contents significantly increased in rice leaves under Cd stress. Compared with no Si application, under different concentrations of Cd stress, the SOD and CAT activities of rice leaves were significantly increased by 20.4%-58.9%, 25.3%-72.5% and 5.8%-11.9%, 22.7%-25.4% in 100 and 300 mg kg−1 Si treatment respectively. POD activities decreased significantly by 21.2%-43.0% and 31.8%-50.8%. At the same time, 300 and 500 mg kg−1 Si significantly reduced MDA and Pro contents in rice leaves.
      Conclusion  different supplemental levels of Si had appreciably improved on growth, leaf chlorophyll content, photosynthetic characteristics and antioxidant system of rice in the pre- fertility period under Cd stress, and the effect of 300 mg kg−1 Si treatment was the best.

     

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