Assessment of the differential trade-off between growth, subsistence, and productivity of two popular Indian hybrid mango varieties under elevated ozone exposure.

The multifunctionality of plants is well known to be compromised in the areas experiencing higher concentrations of tropospheric ozone (O3 ). Mango (Mangifera indica L.) cultivation is essential to the economy of tropical regions, including India. Mango, widely grown in suburban and rural areas, experiences production loss due to air pollutants. Ozone, the most important phytotoxic gas in mango growing areas, warrants an investigation of its effects. Therefore, we assessed the differential sensitivity of mango saplings (two-year-old hybrid and regular-bearing mango varieties, Amrapali and Mallika) at two levels of O3 : ambient and elevated (ambient + 20 ppb) using open-top chambers from September 2020 to July 2022. Under elevated O3 , both varieties showed similar seasonal responses (winter and summer) for all the growth parameters but differed in their height-diameter allocation pattern. A decrease in stem diameter and an increase in plant height were observed in Amrapali, whereas Mallika showed a reverse response. Early emergence of phenophases was noticed during the reproductive growth of both varieties under elevated O3 exposure. However, these changes were more pronounced in Amrapali. Stomatal conductance was more negatively affected in Amrapali than in Mallika under elevated O3 during both seasons. Furthermore, leaf morpho-physiological traits (leaf nitrogen concentration, leaf area, leaf mass per area, and photosynthetic nitrogen use efficiency) and inflorescence parameters responded variably in both varieties under elevated O3 stress. A decrease in photosynthetic nitrogen use efficiency, further enhanced yield loss which was more pronounced in Mallika than in Amrapali under elevated O3 exposure. The results of this study could be useful in selecting a better-performing variety based on its productivity, which will be economically more beneficial in achieving the goal of sustainable production at the anticipated high O3 levels under a climate change scenario.