Impact of elevated ozone on yield and carbon-nitrogen content in soybean cultivar 'Jake'.

Tropospheric ozone (O) is a pollutant that leads to significant global yield loss in soybean [Glycine max (L.) Merr.]. To ensure soybean productivity in areas of rising O, it is important to identify tolerant genotypes. This work describes the response of the high-yielding soybean cultivar 'Jake' to elevated O concentrations. 'Jake' was treated with either low O [charcoal-filtered (CF) air, 12 h mean: 20 ppb] or with O-enriched air (12 h mean: 87 ppb) over the course of the entire growing season. In contrast to the absence of O-induced leaf injury under low O, elevated O caused severe leaf injury and decreased stomatal conductance and photosynthesis. Although elevated O reduced total leaf area, leaf number, and plant height at different developmental stages, above-ground and root biomass remained unchanged. Analyzing carbon and nitrogen content, we found that elevated O altered allocation of both elements, which ultimately led to a 15 % yield loss by decreasing seed size but not seed number. We concluded that cultivar 'Jake' possesses developmental strength to tolerate chronic O conditions, attributes that make it suitable breeding material for the generation of new O tolerant lines.