Low nitrogen levels can affect the growth of maize plants. Researchers studied how different maize varieties respond to low nitrogen stress by looking at their photosynthesis and chlorophyll fluorescence. They found that low nitrogen stress reduced chlorophyll content and certain fluorescence characteristics in leaves. The tolerant maize variety showed less variation in these traits compared to the sensitive variety, especially in the early growth stages. Tolerant plants maintained higher photosynthetic and electron transport rates, which helped them adapt better to low nitrogen conditions. This suggests that tolerant maize varieties have a mechanism to cope with low nitrogen stress by adjusting their photosynthetic processes.