This research sought to investigate the pollution by heavy metals in soil and plants (hazelnut trees and grass plants) in natural biotopes of the Oguz Region, Azerbaijan. Besides the influence of pollution, the study considered variations in fluorescent parameters. The main task was to identify the most sensitive tree species to pollution indicators. An integrated approach to the analysis of pollution from transport gases and solid industrial waste seemed crucial and relevant for the selected hazelnut fields. The decreased ratio of Chl a+b/carotenoids in both hazelnut cultivars (Oily Hazelnut and Ata Baba) authenticates that carotenoids perform a protective function from the natural and anthropogenic factors. More sensitive cultivars of hazelnuts (Oily Hazelnut and Ata Baba) used for research mainly served landscaping purposes (as informal hedges, windbreaks, and erosion control). The study advised planting these cultivars away from roads and even in the second row after bushes as more resistant species to pollution. This is because with increased pollution from exhaust gases (CO₂, CO, and HC), trees become weaker than those away from the roads.

Keywords: Heavy metals, chlorophyll, bioindicators, soil samples, carotenoids, environmental pollution

Key findings: The results revealed the tree species, particularly cultivars Oily Hazelnut and Ata Baba, proved sensitive to environmental pollution in Azerbaijan due to heavy metals and air pollutants. These tree species entailed studies for morphological, physiological, and biochemical variations under polluted conditions and succeeded in their identification as useful bioindicators for environmental monitoring.