The researchers studied how drought affects the photosynthesis of maize leaves. They found that under water stress, the photosynthetic rate, chlorophyll content, and fluorescence parameters decreased. The ratio of photosynthetic rate to chlorophyll ratio, basis fluorescence, and fluorescence parameters correlated with drought resistance. This suggests that the photosynthetic rate, chlorophyll ratio, and fluorescence parameters can be used to evaluate the drought resistance of different maize varieties.