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

Tropospheric ozone (O3) is a pollutant that leads to significant global yield loss in soybean [Glycine max (L.) Merr.]. To ensure soybean productivity in areas of rising O3, it is important to identify tolerant genotypes. This work describes the response of the high-yielding soybean cultivar 'Jake' to elevated O3 concentrations. 'Jake' was treated with either low O3 [charcoal-filtered (CF) air, 12 h mean: 20 ppb] or with O3-enriched air (12 h mean: 87 ppb) over the course of the entire growing season. In contrast to the absence of O3-induced leaf injury under low O3, elevated O3 caused severe leaf injury and decreased stomatal conductance and photosynthesis. Although elevated O3 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 O3 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 O3 conditions, attributes that make it suitable breeding material for the generation of new O3 tolerant lines.