The effects of lead on photosynthetic performance of waxberry seedlings (Myrica rubra)

Abstract

The photosynthesis was investigated 30 d after Pb treatment in Myrica rubra seedlings. The Pb treatment resulted in significantly increased Pb concentrations in shoots. Low Pb concentration exposure (≤2 mM) reduced the net photosynthetic rate (P N ), transpiration rate (E), and stomatal conductance (g s ) without affecting the intercellular CO 2 concentration (C i ), chlorophyll (Chl) content, and Chl fluorescence parameters. At 10 d after severe Pb treatment (≥4 mM), P N was inhibited and accompanied by Chl damage, while at 30 d, the inhibition of P N was followed by an increase of C i and a decrease of g s , E, Chl content, and Chl fluorescence parameters. M. rubra showed a promising prospect for use in the soil phytoremediation, when Pb concentration is low, but the remediation efficiency of M. rubra is limited if Pb exceeds 2 mM.

Effects of Pb and Zn toxicity on chlorophyll fluorescence and biomass production of Koelreuteria paniculata and Zelkova schneideriana young plants

“…Heavy metals often occur in trace concentrations naturally, but they may be concentrated in certain areas as a result of anthropogenic activities including burning of fossil fuels, mining, application of fertilizers and pesticides, industrial wastes, and vehicle emissions. The excess heavy metals have been recognized to have a significant toxicity for animals, plants, microorganisms, and human beings, as well as for environment (Nagajyoti et al 2010, Sun et al 2010, Lee et al 2014, Shen et al 2017, He et al 2018. In southern China, lead (Pb) and zinc (Zn) were the most common heavy metal pollutants in soil (Sun et al 2010, Hladun et al 2016 and the concentrations of these two metals were much higher in this region than the standard criteria of the country (MEPC 2011).…”

Negative Effects on Photosynthesis and Chloroplast Pigments Exposed to Lead and Aluminum: A Meta-Analysis

“…In this meta-analysis, we showed that toxic metals (Pb and Al) affect plant physiology by reducing photosynthetic activity. Although photosynthesis is important to determine plant vigor, it is very vulnerable to stress by toxic metals (He et al, 2018). Due to the toxicity of the metals, the photosynthetic apparatus is impaired, altering stomatal conduction, transpiration rate and the gas exchange associated with internal carbon.…”

“…Plants sensitive to toxic metal contamination, such as the Myrica genus, exhibit toxicity symptoms, indicating the presence of these elements in the environment. The plasma membrane can be affected by toxic metals, since it is the first to establish a relationship with these contaminants (He et al, 2018). Photosynthesis of plants exposed to toxic metal contamination is also compromised, since these elements can reduce the levels of chlorophyll and carotenoids due to the inactivation of the enzymes responsible for the biosynthesis of these pigments.…”

“…It damages the development and negatively affects the physiological and biochemical structures of plants, inhibiting photosynthesis, altering enzymatic activities, and causing the inhibition or reduction of germination and chlorosis in the leaves (Ozyigit et al, 2016). Therefore, Pb has the potential to modify anatomical characteristics, such as the number of stomas, stomatal conductance and the size of vascular bundles (He et al, 2018). Moreover, Pb can cause oxidation of the root system and change the water and hormonal balance.…”

“…Moreover, Pb can cause oxidation of the root system and change the water and hormonal balance. Another important plant response to toxic metal exposure is foliar gas exchange because it reflects different levels of environmental stress and can be directly related to photosynthesis (He et al, 2018). According to Fu and Wang (2015), when Brassica chinensis was exposed to small amounts of Pb (300 mg/ Kg) the metal promoted an increase in photosynthetic capacity and carbon assimilation.…”