<p>The effect of chronic O₃ exposure on two hybrid Indian mango varieties was assessed in terms of growth allometries, biomass accumulation, dynamics of non-structural carbohydrates (NSCs) storage, carbon sequestration and trading. The exposure study was conducted using open-top chambers under ambient (AO₃) and ambient + 20&#xa0;ppb (EO₃) O₃ concentrations for 21&#xa0;months. Growth allometries showed variable responses under EO₃ in both varieties where specific leaf area (SLA) and root shoot ratio (RSR) were decreased, while increments were found in leaf area ratio (LAR) and specific leaf weight (SLW). Elevated O₃ induced an increase in leaf biomass whereas stem, fruit, coarse and fine root biomass reduced significantly in both varieties compared to AO₃. Increments in NSCs in the stem and leaves of both varieties under EO₃ helped to maintain continued growth and development. The total biomass, carbon stock and carbon sequestration potential of the plants decreased significantly under EO₃ in both varieties, but the effects were more detrimental in Mallika. Furthermore, a varietal difference was observed in the preferential allocation of fractional biomass where Amrapali explicitly allocated a higher fraction of biomass to coarse root enhancing its long-term carbon sequestration. Consequently, the total carbon price was reduced by 2.6% in Amrapali and 9.8% in Mallika. The reductions in total biomass, carbon stock, carbon sequestration and carbon price induced by EO₃ of two economically important mango varieties denote the negative impact of rising O₃ concentrations on the carbon trading market of India concomitantly challenging the effort to achieve net zero carbon emission.</p>