Vertical distributions of chlorophyll and nitrogen and their associations with photosynthesis under drought and rewatering regimes in a maize field

Abstract

In this study, we characterize the vertical leaf distribution of chlorophyll (Chl) and nitrogen (N) content and their associations with leaf photosynthetic responses in Zea mays L. under field watering regimes. We simulated five precipitation patterns, including a drought-rewatering sequence using an electric-powered, rainproof shelter. The results indicate the vertical leaf Chl and N distribution versus the cumulative leaf-area index (LAIc) fit well into a significant quadratic function. The simulated precipitation patterns significantly influenced the parabolic curve trajectory patterns and their parameters. Chlorophyll and N contents had the same trend, with a close and positive relationship. Drought stress followed by rewatering increased the slopes of the linear equations but narrowed the parabolic opening of the quadratic functions. This finding implies that the relationship between Chl and N content can be used to estimate responses to drought and rewatering. The findings also suggested that the relationship patterns between Chl and N levels could be an assessment tool for N-fertilizer managements under different drought conditions to maintain high yields in maize production. Principal component analysis indicated the correlations between functional traits in maize leaves and the responses to drought and rehydration. These findings help to improve drought management and cultivar selection, which will be important in coping with the severe intensity and high frequency of episodic drought events expected from climate change.