Synergy between root hydrotropic response and root biomass in maize (Zea mays L.) enhances drought avoidance

Area of Science:

• Plant Biology
• Agronomy
• Genetics

Background:

• Hydrotropism is the directional growth of plant roots in response to moisture gradients.
• Understanding hydrotropism is crucial for improving crop resilience, especially in maize (Zea mays).
• Limited research exists on hydrotropism in grasses, particularly maize, and its link to drought adaptation.

Purpose of the Study:

• To investigate the correlation between enhanced hydrotropic response in maize roots and improved adaptation to drought and varied irrigation conditions.
• To evaluate selected maize hybrids under field conditions to validate laboratory findings.

Main Methods:

• Developed a laboratory bioassay to phenotype the hydrotropic response of primary roots in 47 elite Drought Tolerant Maize for Africa (DTMA) hybrids.
• Conducted field trials with selected robust and weak hydrotropic hybrids under normal, partial lateral, and drought irrigation regimes.

Main Results:

• Maize hybrids with a robust hydrotropic response exhibited distinct growth and developmental patterns under drought and partial lateral irrigation compared to weak responders.
• A positive correlation was observed between root crown biomass and grain yield in robust hydrotropic hybrids.
• Robust hydrotropic responders showed earlier female flowering and enhanced root system architecture (e.g., greater projected root area, depth) and stem diameter.

Conclusions:

• Intensive phenotyping of hydrotropism in primary roots is beneficial for maize breeding.
• Selection for robust hydrotropism is a promising strategy to enhance drought avoidance and improve crop performance under water-scarce conditions.