Impact of root cutting on root architecture and water use efficiency of rice seedlings

【Objective】An optimal root architecture not only provides anchorage for plants but also enhances the acquisition of water and nutrients, which are unevenly distributed in the soil profile. This study experimentally investigates how root cutting can improve the root architecture of rice seedlings and its subsequent impact on water use efficiency.【Method】The experiment used the rice variety Lvhan 639 as the model plant and included two treatments. In the first treatment, half of the root system was removed at 5, 7, 9, and 11 days after seedling emergence. In the second treatment, root cutting was conducted 9 days after seedling emergence, with the root being cut at 1.5 cm from the root tip (A1.5), at the middle of the root (A1/2), and cut the root to 2.0 cm (A2.0). The control group did not undergo any root cutting. In each treatment, we measured root architecture, plant height, stem diameter, root-to-shoot ratio, photosynthetic traits, and water use efficiency of the seedlings.【Result】In the first treatment, the most favorable root architecture was observed when half of the root was cut 7 days after seedling emergence. In the second treatment, (A2.0) produced the optimal root architecture. Root cutting reduced the root-to-shoot ratio in all cases, although the differences between the two treatments were not statistically significant. In the first treatment, the lowest root-to-shoot ratio (0.228 5) occurred when the root was cut 9 days after seedling emergence. Root cutting improved water use efficiency, primarily by decreasing stomatal conductance. In the first treatment, cutting the roots 9 days after seedling emergence increased water use efficiency by 14.93% compared to the control. In the second treatment, cutting the roots to 2.0 cm showed the highest water use efficiency, with a 38.99% improvement over the control.【Conclusion】Root cutting can effectively enhance both root architecture and water use efficiency in rice seedlings. Among the methods tested, cutting half of the root 7 days after seedling emergence or trimming the root to 2.0 cm on the 9th day after seedling emergence were most effective for optimizing root development and increasing water use efficiency.