Bo Shang

Elevated tropospheric ozone (O₃) and global warming can affect nitrous oxide (N₂O) and nitric oxide (NO) emissions from rice paddies, but their interactive effect is poorly understood. Two-year field observations of soil properties were implemented to quantify the impact of elevated O₃ and warming on N₂O and NO fluxes and identify dominant regulatory factors. Results indicated that elevated O₃ reduced N₂O and NO fluxes, whereas warming increased N₂O and NO fluxes, relative to respective ambient conditions. The combined O₃ elevation and warming treatment resulted in reductions in N₂O and NO fluxes compared to the warming treatment. The N₂O and NO emissions under elevated O₃ and warming were primarily associated with significant changes in soil dissolved organic carbon (DOC) and NH₄⁺. Furthermore, under warming treatment, N₂O and NO emissions were also linked to significant variations in soil NO₃⁻, but were independent of soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and pH. This study found that high O₃ concentrations significantly suppress nitrogen oxide emissions from paddy fields under warming. This suppression necessitates the explicit integration of O₃ into agroecosystem emission prediction frameworks for accurate estimation of nitrogen oxide fluxes.

Accurate estimation of regional-scale ozone (O ₃ ) uptake flux is critical for assessing crop stress. Traditional Jarvis-type empirical models are limited in capturing canopy conductance dynamics governed by both environmental conditions and plant physiology. Focusing on the winter wheat region of the North China Plain (NCP), this study integrated sun-induced chlorophyll fluorescence (SIF) data from Sentinel-5P/TROPOMI into a photosynthesis model to retrieve canopy conductance ( G _c _SIF) and dynamically estimate a SIF-based O ₃ uptake flux (POD ₀ _SIF) during a 75-d window centered on flowering (44 d before to 30 d after). Jarvis-model-based POD ₀ (POD ₀ _Jarvis) and AOT40 (accumulated exposure over a threshold of 40 parts per billion) were also calculated for comparison. The results showed good agreement between G _c _SIF and eddy covariance-based canopy conductance estimates ( G _c _EC) at the site scale, with R ² values of 0.59 to 0.67 and 0.41 to 0.46 at the daily and hourly scales, respectively. G _c _SIF exhibited stronger spatiotemporal consistency with gross primary production than Jarvis-based stomatal conductance ( g _s _Jarvis). Spatially, high AOT40 levels were concentrated in the central and northern NCP, while high POD ₀ _SIF and POD ₀ _Jarvis occurred in the central and southern regions. POD ₀ _SIF exhibited greater spatial heterogeneity than POD ₀ _Jarvis, with coefficients of variation of 22.62% and 7.50%, respectively, and their difference (ΔPOD ₀ ) peaking in the western and northern NCP. Vapor pressure deficit (VPD) contributed 32.3% to ΔPOD ₀ , indicating that the Jarvis model inadequately captures the nonlinear stomatal response to varying atmospheric moisture conditions. The POD ₀ _SIF framework provides a physiologically constrained approach for regional-scale O ₃ stress assessment during critical growth stages of winter wheat.

This study investigated the effects of elevated O ₃ level on photosynthetic traits and antioxidant systems of various rice genotypes under fully open-air conditions. Eight modern rice cultivars ( Oryza sativa L.), including 4 hybrids and 4 inbreds, were exposed to 2 O ₃ treatments: the ambient atmosphere (A-O ₃ ) and the 1.5 times ambient O ₃ concentration (E-O ₃ ) throughout the reproductive period. The measurements of gas exchange, chlorophyll a fluorescence, photosynthetic pigments, lipid oxidation, antioxidant content, and antioxidant enzyme activity were conducted on the flag leaf during the early and late grain-filling periods. The results indicated that E-O ₃ had differential effects on the photosynthesis and antioxidant indicators of rice genotypes. In the hybrid rice, the reduction in the light-saturated photosynthetic rate ( A _sat ) was primarily due to the nonstomatal factors, such as the changes in antioxidants, particularly ascorbate and carotenoids. In contrast, the reduction in A _sat levels in inbred rice was mainly due to the stomatal factors. Additionally, the hybrid rice was more sensitive to O ₃ than the inbred rice, with the sensitivity determinants varying between types. The sensitivity of hybrid rice to O ₃ was influenced by the magnitude of its antioxidant capacity, whereas the inbred rice sensitivity was determined by the stomatal conductance ( g _s ) and the antioxidant enzyme activity. The rice cultivars with higher antioxidant enzyme activities could help mitigate the damage caused by O ₃ pollution. This study could provide valuable insights for screening the O ₃ -tolerant rice cultivars and promoting the food security sustainability.

Air pollution and climate change are tightly interconnected and jointly affect field crop production and agroecosystem health. Although our understanding of the individual and combined impacts of air pollution and climate change factors is improving, the adaptation of crop production to concurrent air pollution and climate change remains challenging to resolve. Here we evaluate recent advances in the adaptation of crop production to climate change and air pollution at the plant, field and ecosystem scales. The main approaches at the plant level include the integration of genetic variation, molecular breeding and phenotyping. Field-level techniques include optimizing cultivation practices, promoting mixed cropping and diversification, and applying technologies such as antiozonants, nanotechnology and robot-assisted farming. Plant- and field-level techniques would be further facilitated by enhancing soil resilience, incorporating precision agriculture and modifying the hydrology and microclimate of agricultural landscapes at the ecosystem level. Strategies and opportunities for crop production under climate change and air pollution are discussed.

Ethylenediurea (EDU) is an indicator of surface ozone (O₃), has a high potential to be developed as an applicable protectant for crops against O₃ phytotoxicity. Studies on the effects of EDU on grain quality are few, limiting evaluation of the efficiency of EDU protection. In order to understand the effects of EDU on grain quality in rice, a field study was conducted in a rice paddy, where EDU solutions were foliar applied to rice plants. At maturity, grain nitrogen concentrations (GN) in 21 rice cultivars and related traits were analyzed. Mean across 21 cultivars, GN was reduced by EDU by 3.81%, suggesting that O₃ in ambient air is affecting grain quality. GN negatively correlated with grain weight and source/sink ratio, but positively correlated with spikelet density. Moreover, GN changes to EDU were rice type dependent, which were −0.43%, −0.72%, and 1.19% in indica, japonica, and hybrid rice, respectively. These results suggest that EDU promotes sink in rice, which helps to increase grain yield, but allocation of nitrogen is not enough to maintain GN in both indica and japonica cultivars. Rice types and cultivars’ variations in the responses of GN to EDU highlight a possibility to adjust grain quality by EDU, combining cultivar selection and agricultural management in response to surface O₃ pollution.