Pb2+ 和Zn2+胁迫下3种草坪草光合特征及吸附重金属能力差异性

Differences of photosynthetic characteristics and adsorption capacity of three turfgrass under Pb2+ and Zn2+ stresses

摘要:

【目的】探索 Pb²⁺、Zn²⁺污染地区最适宜的修复草坪草品种。【方法】采用盆栽的方法，以黑麦草（Lolium perenne）、高羊茅（Festuca arundinacea）和草地早熟禾（ Poa pratensis）为研究对象，以河沙为栽培基质，测定各处理的光合指标和重金属含量。设置不加重金属（CK）、Pb²⁺ 胁迫（500、1 000、1 500、2 000 mg/L）、Zn²⁺胁迫（500、800、1 100、1 400 mg/L）处理。测定不同重金属浓度胁迫下的草坪草的光合特征及其对重金属吸收能力。【结果】研究表明：随着 Pb²⁺ 、Zn²⁺浓度的增加，3 种草坪草净光合速率、气孔导度、蒸腾速率和胞间 CO₂浓度均呈先升高后降低趋势，但是出现峰值的浓度梯度各异；当 Pb²⁺ 胁迫浓度为 500 mg/L 时，对高羊茅和黑麦草叶片光合能力具有促进作用；当 Pb²⁺ 胁迫为 1 000 mg/L 时，对草地早熟禾叶片光合能力具有促进作用。当 Zn²⁺胁迫为 800 mg/L 时对黑麦草和高羊茅叶片净光合速率具有促进作用；当 Zn²⁺ 胁迫为 500 mg/L 时，对草地早熟禾叶片净光合速率具有促进作用。【结论】综合分析 3 种草坪草的光合特征和对植物体内重金属富集能力表明，高羊茅和黑麦草适用于低于 1 000 mg/L 的 Pb²⁺、Zn²⁺污染土壤的修复。

Abstract:

【Objective】 To explore the most suitable varieties of lawn grass for restoration in Pb²⁺and Zn²⁺pol- luted areas.【Method】 Using a pot culture method，Lolium perenne，Festuca arundinacea，and Poa pratensis as the re- search objects，and river sand as the cultivation medium，the photosynthetic index and heavy metal content were mea- sured for each treatment. The Treatments were without adding heavy metals （CK），Pb²⁺stress （500，1 000，1 500， 2 000 mg/L），and Zn²⁺ stress （500，800，1 100，1 400 mg/L）. The photosynthetic characteristics and heavy metal ab- sorption capacity of turfgrass under different concentrations of heavy metal stresses were measured.【Result】 The re- sults showed that with the increase of Pb²⁺ and Zn²⁺ concentrations，the net photosynthetic rate，stomatal conduc- tance，transpiration rate，and intercellular CO₂ concentration of the three lawn grasses all showed a trend of first in- creasing and then decreasing，but the concentration gradients with peak values varied； When the concentration of Pb²⁺ stress was 500 mg/L，it promoted the photosynthetic capacity of tall fescue and ryegrass leaves；When Pb²⁺stress was 1 000 mg/L，it promoted the photosynthetic capacity of Poa pratensis leaves. When Zn²⁺stress was 800 mg/L，it promoted the net photosynthetic rate of ryegrass and tall fescue leaves；When Zn²⁺ stress was 500 mg/L，it promoted the net photosynthetic rate of Poa pratensis leaves.【Conclusion】 A comprehensive analysis of the photosynthetic and heavy metal accumulation abilities of three lawn grasses showed that tall fescue and ryegrass were suitable for the remediation of Pb²⁺ and Zn²⁺ contaminated soil below 1 000 mg/L.