Growth Responses and Photosynthetic Indices of Bamboo Plant (Indocalamus latifolius) under Heavy Metal Stress.

Abolghassem Emamverdian,Farzad Mokhberdoran,Yinfeng Xie,Yulong Ding

doi:10.1155/2018/1219364

Abolghassem Emamverdian, Farzad Mokhberdoran + Show 2 more

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https://doi.org/10.1155/2018/1219364

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Abstract

Investigating factors involved in the alleviation of the toxic effects of heavy metals (HMs) on plants is regarded as one of the important research concerns in the environmental field. The southern regions of China are severely impacted by human-induced heavy metal (HM) contamination, which poses an impediment to growth and productivity of bamboo (Indocalamus latifolius) plants. This necessitates the investigation of the effects of HMs on growth and physiological properties of bamboo. Therefore, the aim of the study was to evaluate some gas exchange and growth parameters in two-year-old bamboo species under HMs stress. A greenhouse-based experiment was conducted at Nanjing Forestry University, where the bamboo plant was treated with three HMs (Cu, Pb, and Zn) at four different concentrations (0, 500, 1000, and 2000 mg kg-1). The results illustrated that excessive HMs (1000 and 2000 mg kg−1) triggered a decline in a number of photosynthetic-related indices including the rate of photosynthesis (μmol CO2 m−2 s−1), intercellular CO2 concentration (μmol CO2 mol−1), conductance to H2O (mol H2O m−2 s−1), and net assimilation as well as transpiration. Morphological indices were also depressed as a result of the adverse influence of HMs, leading to decreased shoot length (10 to 73%) and reduced number of emerged plants (6 to 57%). Also, the results indicated that Pb had the greatest harmful impact on the growth indices.

Highlights

The excessive levels of heavy metals (HMs) in the soil, which mainly stem from human-induced activities, are a major threat to human health, plant productivity, and wildlife [1, 2]
Photosynthetic measurements revealed that high concentrations of HMs had a negative impact on the bamboo gas exchange parameters, at the elevated levels (1000–2000), which led to a significant reduction in the photosynthetic indices including photosynthetic rate (PN), conductance to H2O (Cond), Ci, and transpiration rate (Tr)
Bamboo plants are exposed to this abiotic stressor in southern China, which makes it essential for researchers to conduct relevant studies to fully understand the pernicious effects of HMs on various biological and physiological aspects of bamboo

Summary

Introduction

The excessive levels of heavy metals (HMs) in the soil, which mainly stem from human-induced activities, are a major threat to human health, plant productivity, and wildlife [1, 2]. The extreme concentration of metals in the soil can bring about detrimental changes to plant photosynthesis, eventually leading to the reduction of plant growth and yield [7]. They are capable of causing oxidative stress in plants via generating, e.g., “Reactive Oxygen Species (ROS)” [8]. Heavy metals can indirectly impact plants by disrupting electron transport chain and superseding essential elements [9]. Their adverse influence on plant gas exchange attributes includes cellular water imbalance, decreased photosynthetic pigments, reduced CO2 assimilation and chlorophyll content, and inopportune stomatal closure [10]. Heavy metals can inflict physical damage upon roots and leaves, leading to

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