Investigating the potency of ethylenediurea (EDU) in alleviating the affliction of ambient ozone in heat labile tomato cultivars (Solanum lycopersicum L.)

Tomato is the second most valuable vegetable crop, and its susceptibility to tropospheric ozone (O3) varies on the cultivar. Eight tomato cultivars with documented O3 sensitivity were reevaluated using ethylenediurea (400 ppm EDU) to determine the effectiveness of EDU in assessing O3 sensitivity under heavily O3-polluted tropical conditions. EDU helped in amending the growth, photosynthetic pigments, photosynthetic rate, stomatal conductance, and yield characteristics in the tomato cultivars. EDU reduced the lipid peroxidation and reactive oxygen species content, while enzymatic and non-enzymatic antioxidant responses differed across cultivars. The cultivar Superbug and Sel-7 (O3 susceptible) performed better by employing more biomass and yield and exhibiting more potent antioxidative defense machinery mainly non-enzymatic antioxidants after EDU treatment. The higher value of total antioxidative potential (TAP) in O3 susceptible cultivars suggested the adaptive resilience through EDU application against O3 stress. EDU application greatly enhanced the photosynthetic rate in O3 susceptible cultivars by increasing the stomatal conductance. Hence, both biophysical and biochemical responses were involved in protection against O3 provided by EDU. Kashi chayan and VRT02 (O3 tolerant) cultivars showed least response to EDU, due to their efficient inherent mechanisms in alleviating O3 stress. Thus, EDU may be used as an efficient biomonitoring tool against O3-sensitive cultivars.