Can mild alternate wetting and drying irrigation modify lodging risk of rice under elevated ozone concentration?

Rice is the main food crop for over half of the global population. Lodging represents a critical yet unpredictable factor threatening rice production security and agricultural water resource utilization efficiency. Rice lodging is affected by many factors, such as alternate wetting and drying irrigation (AWD) or elevated ozone concentration (E[O 3 ]). However, the combined effect of E[O 3 ] and AWD on lodging of rice remains unclear. Here, we investigate whether mild AWD can impact the response of lodging resistance and stem-related traits of indica rice to E[O 3 ] using an open-top chamber (OTC) system under field condition in 2023–2024. The experiment involved two levels of [O 3 ] (A[O 3 ], ambient; E[O 3 ], 60 ppb above ambient) and two irrigation methods (FL, flooding irrigation; mild AWD). The results showed that E[O 3 ] significantly increased the lodging index of second basal internode by 16.4 %-34.2 % as a result of decreasing the values of key parameters such as breaking resistance and dry weight per unit length. Mild AWD significantly reduced the lodging index by 10.4 %-20.6 % for second basal internode and 12.1 %-17.0 % for third basal internode, which was attributed to enhanced breaking resistance, dry weight per unit length, long and short axis diameter in basal internodes. Furthermore, no significant interaction was found between [O 3 ] and irrigation methods on lodging index of rice, indicating that mild AWD cannot completely mitigate the lodging risk induced by ozone. The findings indicate that the risk of O 3 -induced lodging in rice may persist even if eco-friendly management practices such as mild AWD are employed. • Yield is negatively correlated with the lodging index. • O 3 increased lodging risk due to thinner internode and lower stem density. • Mild AWD reduced lodging risk as a result of thicker internodes and higher stem density. • Mild AWD cannot completely mitigate the lodging risk induced by elevated ozone concentration.