| Summary: | The spatiotemporal heterogeneity in the concentrations of atmospheric CO<sub>2</sub> and tropospheric O<sub>3</sub> is increasing under climate change, threatening food security. However, the impacts of short-term elevated CO<sub>2</sub> or O<sub>3</sub> on undamaged kernels in rice remain poorly understood, especially the impacts of their combination. We conducted an open-top chamber experiment to examine the impacts of short-term elevated CO<sub>2</sub> (+200 ppm, eCO<sub>2</sub>) and O<sub>3</sub> (+40 ppb, eO<sub>3</sub>) on undamaged kernels in rice cultivars (NJ5055 and WYJ3). We found eCO<sub>2</sub> significantly reduced undamaged kernels by 35.2% and 66.2% in NJ5055 and WYJ3, respectively. EO<sub>3</sub> significantly reduced undamaged kernels by 52.4% and 47.7% in NJ5055 and WYJ3, respectively. But the combination of eCO<sub>2</sub> and eO<sub>3</sub> did not affect the undamaged kernels in both cultivars. Moreover, we found that undamaged kernels were significantly correlated with chalky kernels (<i>r</i> = −0.9735). These results highlighted that changes in chalky kernels are most responsible for the changes in undamaged kernels in rice under eCO<sub>2</sub> and eO<sub>3</sub>. This study demonstrated that undamaged kernels in rice are fragile to climate change factors like short-term eCO<sub>2</sub> and eO<sub>3</sub>, and reducing chalky kernels is one of the most important adaptations to sustain food security in the future.
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