Morpho-physiological growth performance and phytoremediation capabilities of selected xerophyte grass species toward Cr and Pb stress

Taimoor Hassan Farooq; Muhammad Rafay; Hamza Basit; Awais Shakoor; Rubab Shabbir; Muhammad Umair Riaz; Baber Ali; Uttam Kumar; Kamal Ahmad Qureshi; Mariusz Jaremko

doi:10.3389/fpls.2022.997120

Morpho-physiological growth performance and phytoremediation capabilities of selected xerophyte grass species toward Cr and Pb stress

Front Plant Sci. 2022 Sep 8:13:997120. doi: 10.3389/fpls.2022.997120. eCollection 2022.

Authors

Affiliations

¹ Bangor College China, A Joint Unit of Bangor University and Central South University of Forestry and Technology, Changsha, China.
² Department of Forestry, Range and Wildlife Management, Faculty of Agriculture, The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
³ Teagasc, Environment, Soils and Land Use Department, Johnstown Castle, Co., Wexford, Ireland.
⁴ Department of Plant Breeding and Genetics, Seed Science and Technology, University of Agriculture, Faisalabad, Pakistan.
⁵ Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan.
⁶ College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China.
⁷ Department of Pharmaceutics, Unaizah College of Pharmacy, Qassim University, Unaizah, Saudi Arabia.
⁸ Division of Biological and Environmental Sciences and Engineering, Smart-Health Initiative and Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.

Abstract

Being sessile organisms, plants cannot escape unwanted changes in the environment. The rapid human population explosion caused significant environmental problems. Heavy metals produced through various sources can cause severe damage to living organisms. The study was planned to evaluate four grass species' morpho-physiological growth characteristics and phytoremediation capabilities under chromium (Cr) and lead stress (Pb) in the arid climate. Typha angustifolia, Tragus roxburghii, Aeluropus logopoides, and Cenchrus ciliaris grass species were used for the study. One-year-old stubbles from the Cholistan desert were used for the experiment. Cr treatments in the form of K₂Cr₂O₇ were applied at 0, 20, 40, and 80 mg L^-1, whereas Pb was applied as PbCl₂ at 0, 50, 200, and 500 mg L^-1 as control, low, moderate and high-stress, respectively. After 6 weeks of heavy metals treatments, plants were harvested and analyzed for growth performance and phytoremediation capabilities. Results depicted that, regarding morphological attributes, T. angustifolia performed better, followed by C. ciliaris; no clear pattern was observed for T. roxburghii and A. logopoides. The CO₂ assimilation rate (Co₂d) and water use efficiency (WUE) increased as the heavy metal stress increased in all species under both metals. In contrast, total chlorophyll content was higher under low stress. Other physiological parameters, such as relative humidity (RHd), net photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), leaf internal CO2 concentration (Ci) and membrane stability index (MSI) gradually decreased as the Cr, and Pb stress levels increased among all the species. Moreover, Cr and Pb absorption contents of T. angustifolia were higher than the other three species at each stress level. Overall, T. angustifolia thrived against heavy metals stress and showed higher biomass, maximum photosynthetic measurements, WUE and higher metal absorption among all the selected species. Results concluded that although all the selected species behaved fine under stress conditions, T. angustifolia performance was better; thus, it can be used to remediate the soil near industrial estates.

Keywords: Cholistan; biochemical attributes; dry climate; gas exchange; heavy metals; productivity.