To study the effects of different irrigation volumes on the agronomic traits, lodging resistance and yield formation of rice, and to explore a more suitable water management plan for high-yield and stable-yield green cultivation of rice, and to provide a theoretical basis for sustainable rice production.

Using WYD4 and JND667 as experimental materials, six different irrigation volume treatments were carried out: W1 (12000 m³·hm^-2), W2 (10500 m³·hm^-2), W3 (9000 m³·hm^-2), W4 (7500 m³·hm^-2), W5 (6000 m³·hm^-2) and W6 (natural rainfall). By studying the effects of different irrigation volumes on the plant architecture, resistance to lodging, photosynthetic characteristics, dry matter accumulation and yield of rice, the regulatory effects and mechanisms of different irrigation volumes on these aspects were clarified.

Reducing irrigation properly increased the final tiller number, the percentage of productive tillers, leaf length of the top three leaves, and leaf area index of rice, while reducing the leaf width and leaf base angle of the top three leaves, as well as plant height. The W4 treatment can optimize the plant morphology of rice, promote plant growth, and form a good population structure. With the decrease in irrigation volume, the length of the second internode at the base of rice decreased, and the internode plumpness, breaking resistance, lodging index, and the contents of lignin and cellulose in the stem and sheath first increased and then decreased. Proper irrigation was beneficial for improving the lodging resistance of rice stems. Appropriate irrigation volume not only improves water use efficiency but also enhances the photosynthetic performance of the flag leaves of rice, the accumulation and transportation capacity of dry matter in the stem and sheath, which is beneficial to yield formation. Compared with the W1 treatment, the W4 treatment saved 37.50% of the irrigation water consumption, and the yield significantly increased by 9.07%-12.47%.

Under the W4 (7500 m³·hm^-2) treatment, rice has better plant morphology, lodging resistance, photosynthetic performance, and dry matter accumulation compared with other treatments. Therefore, it has the highest yield while having a high water use efficiency and can be used as a more suitable irrigation volume in this region.