Interactive Effects of Elevated Ozone and Temperature on Growth and Yield of Soybean (Glycine max (L.) Merr.) under Field Conditions

Abstract

Elevated ozone and rising temperature are both factors in climate change, but they are difficult to study in combination due to exposure system requirements. We developed and deployed an air exclusion exposure system to treat soybean (Glycine max (L.) Merr.) cultivar “Jake” with season-long combinations of sub-ambient ozone (18 ppb, 12 h mean), elevated ozone (66 ppb, 12 h mean), and elevated temperature (+3.5 °C daytime, +2.4 °C nighttime) in irrigated field plots. Warming caused a shift in biomass partitioning from reproductive tissues into stems and petioles at mid-season that resulted in a significant 25% reduction in final seed yield and a significant reduction in harvest index. The elevated ozone treatment delayed mid-season biomass production, and final seed yield was reduced by a non-significant 2%. However, there were significant underlying effects of elevated ozone on seed production. The non-significant impact of ozone on seed yield of cultivar “Jake” resulted from significant increases in pod number (+16%) and seed number (+18%) that were offset by a significant reduction in seed size (−16%). No evidence of significant warming–ozone interactions was found in biomass or seed yield responses. In general, significant impacts of the individual warming or ozone treatments were found to be additive.

Warming and elevated ozone induce tradeoffs between fine roots and mycorrhizal fungi and stimulate organic carbon decomposition

“…The field experiment was established in June 2013. The field manipulation experiment had a 2 × 2 factorial design with two levels of temperature (ambient versus elevated +3°C) and two targeted concentrations of O 3 (low at 20 ppbv versus high at 60 ppbv) in a soybean agroecosystem (63,64). This led to a total of four treatment combinations: laid out in a randomized block design with three replicates of each treatment.…”

“…This study was a component of a long-term field manipulation experiment at the Lake Wheeler farm of North Carolina State University, Raleigh, NC, USA (35°43′N, 78°40′W; elevation, 120 m) (63). The field experiment was established in June 2013.…”

“…The field experiment was established in June 2013. The field manipulation experiment had a 2 × 2 factorial design with two levels of temperature (ambient versus elevated +3°C) and two targeted concentrations of O 3 (low at 20 ppbv versus high at 60 ppbv) in a soybean agroecosystem (63,64). This led to a total of four treatment combinations: (a) charcoal-filtered air and ambient temperature (CF); (b) charcoal-filtered air plus 3.0°C increase in temperature (W); (c) charcoal-filtered air plus ambient temperature and 1.3 times ambient ozone (eO 3 ); (d) charcoal-filtered air + warming + 1.3 times ambient ozone (W + eO 3 ).…”

“…Each AES consisted of two double-walled, open-top chamber panels attached to aluminum frames and placed in parallel. The warming treatments (W and W + eO 3 ) were achieved by addition of warming, humidified air to increase the ambient air temperature by 3.0°C, taking the control (CF) as the baseline (63). In this system, electrical resistance heaters and solar-heated water were used to warm the air.…”

Effects of ozone water irrigation and spraying on physiological characteristics and gene expression of tomato seedlings

“…When the concentration of ozone in the environment is high enough, it will cause serious damage to clover leaves 31 . At the same time, high-concentration ozone treatment can reduce the contents of chlorophyll, carotenoids, and carbohydrates in citrus plants 32 and decrease biomass production in mid-season soybean 33 . In recent years, ozone has become a research hotspot because of its high efficiency, lack of residues, strong oxidative abilities, and other advantages.…”