Assessment of Air Pollution Tolerance Index (APTI) and Physiological Response of Selected Urban Tree Species in Jaipur City, India

Abstract

Air pollution poses a critical challenge in industrial and urban areas, severely affecting both environmental quality and plant health. The present study evaluated the Air Pollution Tolerance Index (APTI) and associated physiological responses of seven urban tree species—Azadirachta indica, Acacia nilotica, Ziziphus mauritiana, Prosopis cineraria, Polyalthia longifolia, Alstonia scholaris, and Ficus religiosa—in the Vishwakarma Industrial Area (VKIA), Jaipur, India. Leaf samples were collected during winter (December 2023–February 2024) and summer (April–June 2024) to analyze four key biochemical parameters: ascorbic acid, total chlorophyll, leaf extract pH, and relative water content, following standard protocols (Arnon, 1949; APHA, 2017; Weatherley, 1950). APTI values were computed to determine species-specific and seasonal tolerance variation. Results revealed that A. indica (APTI = 13.5 winter, 12.6 summer) and F. religiosa (12.9 winter, 12.0 summer) were the most tolerant species, while A. scholaris (9.8 winter, 9.3 summer) was the most sensitive. Higher APTI in winter indicated favorable physiological conditions for tolerance, attributed to greater hydration and antioxidant activity. Correlation analysis showed strong positive associations of APTI with ascorbic acid and relative water content. The findings identify A. indica and F. religiosa as suitable candidates for greenbelt development in polluted industrial zones of semi-arid cities like Jaipur.