Comparative assessment of leaf photosynthetic traits for improved carbon dioxide fixation in selected tree species of Pachamalai hills

Forest plays a major role in the carbon dioxide (CO 2 ) sequestration process, understanding that the CO 2 sequestration capacity of individual tree species is essential for the effective management of atmospheric CO 2 . In this regard, 50 tree species belonging to 23 families from Pachamalai hills were taken. After the initial screening, 24 tree species were subjected to leaf anatomy, morphology, physiology, and biochemical studies. The anatomical study revealed that A. heterophyllus, F. benghalensis, A. eleagnoidea, A. occidentale, F. religiosa, and M. peltata have high leaf thickness, stomatal density, and stomatal pore index. The morphological study showed that T. grandis, M. peltata, and G. arborea have more leaf area index, specific leaf area, and petiole length. The physiological study suggested maximum CO 2 assimilation rate, stomatal conductance, and intercellular CO 2 concentration in leaves of M. peltata, F. religiosa, and M. indica . The biochemical characteristics of leaves revealed that F. religiosa, P. marsupium, and S. album possessed high content of total chlorophyll pigments. Further, based on the parameters 15 tree species were shortlisted for the photosynthetic enzyme (rubisco, phosphoenolpyruvate carboxylase, and carbonic anhydrase) activity in leaves. The enzyme activity was higher in M . peltata, Mangifera indica, F. benghalensis, and F. religiosa; further , RT-qPCR analysis of genes involved in CO 2 fixation and photosynthesis confirmed higher expression in M. peltata, and Mangifera indica . The study highlighted the importance of Macaranga peltata, Mangifera indica, Ficus benghalensis, and Ficus religiosa in photosynthetic CO 2 assimilation. These findings can be incorporated into atmospheric CO 2 maintenance programs toward climate change mitigation.