施磷对镉胁迫下黄瓜苗期光合作用及抗氧化酶系统的影响

Effects of Phosphorus on Photosynthesis and Antioxidant Enzyme System of Cucumber Seedlings under Cadmium Stress

    摘要
  • 摘要:
      目的  探究石灰性土壤中施磷对镉胁迫下黄瓜苗期光合作用及抗氧化酶系统的影响，为合理施用磷肥、缓解镉毒害提供依据。
      方法  采用盆栽完全组合设计方案，研究了不同土壤镉添加水平（0、1、3和5 mg kg−1土）下施加不同浓度磷（0、50、100、150和200 mg P2O5 kg−1土）对黄瓜苗期生物量、叶片光合作用及抗氧化酶系统的影响。
      结果  随着施Cd量的增加，黄瓜生物量先增后降，黄瓜叶片的净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）显著降低，胞间CO2浓度（Ci）呈上升趋势。施加适量磷（≤ 150 mg P2O5 kg−1）能够显著提高黄瓜生物量、Pn、Gs、Tr、叶绿素总量和类胡萝卜素含量（Car），降低叶片中Ci。对于抗氧化酶系统来说，随着施Cd量的增加黄瓜叶片中过氧化物酶（POD）、过氧化氢酶（CAT）活性显著降低，丙二醛（MDA）含量明显增加。施磷后，能够明显增强抗氧化酶系统。施Cd量为1 mg kg−1，施磷量为50和100 mg P2O5 kg−1时，CAT活性增加了1.9% ~ 9.6%。施Cd量为3和5 mg kg−1时，随着施磷量的增加，POD和CAT活性出现不同程度增加，与不施磷相比，POD活性分别增加了149.1% ~ 197.8%和150.4% ~ 252.0%，CAT活性分别增加了5.8% ~ 16.6%和0.55% ~ 19.4%，其中施磷量为100 mg P2O5 kg−1时黄瓜叶片POD和CAT活性达到最大。同时，施P能够降低叶片中MDA含量，且随着施磷量的增加而降低。
      结论  在石灰性土壤中，施磷量为100和150 mg P2O5 kg−1时，能够明显缓解镉毒害，增强黄瓜叶片的光合作用及抗氧化酶系统，而施磷量达到200 mg P2O5 kg−1时则对黄瓜生长产生抑制作用。

     

    Abstract:
      Objective  To explore the effects of phosphorus application on photosynthesis and antioxidant enzyme system of cucumber seedlings under cadmium (Cd) stress in calcareous soil , and to provide a scientific basis for rational application of phosphate fertilizers and alleviation of Cd toxicity.
      Method  Under different Cd addition levels (0, 1, 3, 5 mg kg−1), the effects of different phosphorus concentrations (0, 50, 100, 150, 200 mg P2O5 kg−1) on cucumber seedling biomass, leaf photosynthesis and antioxidant enzyme system were studied by using the pot complete random design scheme.
      Result  Under the single Cd treatment, with the increase of Cd application, the biomass of cucumber increased first and then decreased, the net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of cucumber leaves were significantly reduced, and the intercellular CO2 concentration (Ci) increased. The addition of appropriate phosphorus ( ≤ 150 mg P2O5 kg−1) were significantly increased the cucumber biomass, Pn, Gs, Tr, total chlorophyll and carotenoid content (Car), and reduced Ci in cucumber leaves. For the antioxidant enzyme system, with the increase of Cd application, the activities of peroxidase (POD) and catalase (CAT) in cucumber leaves decreased significantly, and the content of malondialdehyde (MDA) increased significantly. After applying P, the antioxidant enzyme system can be significantly enhanced. When the application of Cd was 1 mg kg−1 and phosphorus application of 50-100 mg P2O5 kg−1, the CAT activity increased by 1.9%-9.6%%. When the amounts of Cd applied were 3 and 5 mg kg−1, the POD and CAT activities increased to varying degrees with the increase of P application. Compared with no P application, the POD activities increased by 149.1%-187.8% in 3 mg Cd kg−1 treatment, 150.4-252.0% in 5 mg Cd kg−1 treatment, and the CAT activities increased by 5.8 %-16.6 %, 0.55%-19.4%, respectively. The POD and CAT activities of cucumber leaves reached the maximum value when the phosphorus application of 100 mg P2O5 kg−1. At the same time, P application could reduce the MDA content in leaves, and gradually decreased with the increase of P application.
      Conclusion  In calcareous soil, the phosphorus application rate of 100 or 150 mg P2O5 kg−1, it can significantly alleviate the Cd toxicity and enhance the photosynthetic characteristics and antioxidant enzyme system of cucumber leaves, while phosphorus applications up to 200 mg P2O5 kg−1 inhibited the growth of cucumber.

     

    • HTML全文
    • 参考文献(38)
    • 相关文章
    • 施引文献
  • 资源附件(0)

/

返回文章
返回