Proline and other physiological changes as an indicator of abiotic stress caused by heavy metal contamination

Abstract

Heavy metal pollution due to globalization becomes the incurable hazardous problem for the agriculture productivity is due to industrialization with increased population. In this article impact of stress caused by heavy metals on shoot and root development along with phytoaccumulation was studied. The heavy metals cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb) and nickel (Ni) are taken at varying concentrations ranging from 0 to 250 ppm, while cadmium concentrations ranged from 0 to 50 ppm. The findings revealed that seed germination and plant growth were impacted due to higher percentages of these metals under study. Among them copper, nickel, lead and cadmium exhibited the most pronounced effects on chlorophyll content, root and shoot growth as well as on seed germination, moreover, the physiological analysis indicated that increasing heavy metal concentrations induced greater stress, resulting in decreased chlorophyll content and elevated proline levels, underscoring the significant impact of stress caused by heavy metals on the growth of plants. Delayed germination and growth were observed across all replicates with increased concentrations of all tested heavy metals. Despite zinc being an essential nutrient for plant growth, it was noted that it exhibited a positive effect on chlorophyll content and stimulated the production of fibrous roots, although growth was delayed at higher concentrations. The phytoaccumulation of heavy metals was analysed using atomic absorption spectroscopy (AAS) to quantify the absorption of heavy metals by seedlings, thereby assessing the accumulation or evaporation of heavy metals.

Keywords

• Phytoremediation
• Proline content
• Chlorophyll content
• AAS
• Heavy metals
• Soil extraction