Differential Growth and Metal Accumulation Response of Brachiaria Mutica and Leptochloa Fusca on Cadmium and Lead Contaminated Soil

ABSTRACT

This work aims to assess growth, physiology, and metal uptake response of Brachiaria mutica and Leptochloa fusca under different contamination levels of Cd (10 and 50 mg kg⁻¹) and Pb (50 and 250 mg kg⁻¹) stress. Results of pot trial showed increasing metal concentration affected B. mutica more as compared to L. fusca. In B. mutica metal stress substantially reduced shoot dry biomass, root dry biomass, total chlorophylls, and carotenoids contents by 89%, 85%, 65%, and 61%, respectively, while enhanced the SOD activity up to 62 U min⁻¹ g⁻¹ FW. L. fusca showed better growth, chlorophylls and carotenoid contents, SOD activity (up to 79 U min⁻¹ g⁻¹ FW), shoot metal uptake potential (Cd 110 µg pot⁻¹, Pb 91.57 µg pot⁻¹), and root metal concentration (Cd 126 mg kg⁻¹ dm, Pb 117 mg kg⁻¹ dm) compared to B. mutica under Pb and Cd stress. While both grass species showed metal translocation factor less than unity under all levels of metal stress. Keeping in view the above results, it is concluded that L. fusca having better growth and physiology with TF < 1 could be used for phytostabilization of Pb and Cd to reclaim the soil having moderate to lower levels of contamination.

KEYWORDS:

• Cadmium
• lead
• grass species
• metal uptake
• physiology
• phytoremediation

Acknowledgments

We are thankful to Dr Abdul Rasul Awan, Principal Scientist (NIAB) for providing plant material for the experiment. The technical assistance by Muhammad Sajid, Ms Faiza Mureed, and Mr Khaleeq ur Rehman is also gratefully acknowledged.

Highlights

• Salt tolerant grass species (Brachiaria mutica, Leptochloa fusca) were grown on metal (Cd, Pb) contaminated soils

• Metal contamination retarded growth and enhanced superoxide dismutase activity of grass species

• Major proportion of Pb and Cd retained in roots in comparison to shoot

• Further research at the molecular level to evaluate the intrinsic ability of L. fusca to uptake Cd and Pb in combination with microbes is warranted