The study looked at how different amounts of nitrogen fertilizer affect the growth of ratoon rice. They found that using the right amount of nitrogen can help the main rice plant produce more dry matter, which then helps the ratoon rice plant grow better. By applying the optimal nitrogen level, the amount of dry matter transferred from the main rice to the ratoon rice increased, leading to higher grain yield in the ratoon crop. The best grain yield was achieved with 241.3 kg·hm-2 of nitrogen fertilizer.