The researchers studied a special type of rice called IR64-NIL12 to see how it grows with different amounts of fertilizer. They found that this rice produced more grains than regular IR64 rice, no matter the fertilizer level. The special rice had changes in traits like plant height and tiller number, which helped it catch more sunlight. They also discovered that a specific gene in the special rice increased the weight of each tiller, leading to more spikelets per panicle. This gene could be important for improving rice yields in the future.