Nitrogen enhances drought tolerance of maize during the jointing stage by increasing the proportion of deep nodal roots and reducing the biosynthesis of lignin in root system

Background and aims

Drought has a substantial adverse impact on maize growth during the jointing stage. Nitrogen (N) is an essential nutrient that fosters the growth and yield of maize. However, the underlying mechanisms behind the connection between N and drought tolerance require elucidation.

Methods

In this study, we explored the effects of drought and N application on maize during the jointing stage using soil column cultivation. The investigation includes phenotypic analyses, measurements of physiological indexes, microstructural observations, and proteomics analyses.

Results

The impacts of N on maize plants under drought stress were as follows: (1) The supply of N enhanced the root water uptake capacity by reducing the biosynthesis of lignin in the root endodermis and increasing the proportion of deep nodal roots; (2) N reduced the inhibition of photosynthate assimilation caused by drought, resulting in increased leaf area, chlorophyll content, biomass and higher levels of growth-promoting hormones; (3) N improved drought tolerance in maize plants, probably caused by N strengthening the root antioxidant system and thus maintaining reactive oxygen species (ROS) homeostasis.

Conclusions

The physiological mechanisms of N in alleviating drought in maize at the jointing stage, as explored in this study, provide a theoretical foundation and potential strategies for dryland maize cultivation or the selection and design of new drought-tolerant maize lines.