The study looked at how different soybean varieties respond to varying levels of nitrogen in terms of their growth and yield. They found that high nitrogen-efficient varieties had better root activity, nitrate reductase activity, and photosynthetic rate at low nitrogen levels, but performed worse at high nitrogen levels compared to low-efficient varieties. High-efficient varieties also had lower nitrogen and chlorophyll content in their leaves. The results suggest that high-efficient varieties should be given less nitrogen fertilizer, while low-efficient varieties may benefit from more nitrogen fertilizer to improve their growth and yield.