Genotypic Variation in Maize Root Hydrotropism and Its Association with Shoot Growth and Water Use Efficiency Under...

Area of Science:

• Plant Science
• Agricultural Science
• Drought Stress Physiology

Background:

• Drought significantly reduces maize yields globally.
• Partial root-zone drying (PRD) enhances water use efficiency (WUE), but genotypic variability in yield response exists.
• Root hydrotropism, the directional growth of roots towards water, is a potential factor influencing drought adaptation.

Purpose of the Study:

• To investigate the variation in root hydrotropism among different maize genotypes.
• To assess the relationship between hydrotropic response, root distribution, and shoot performance under partial root-zone drying (PRD).
• To determine if root hydrotropism and specific shoot traits contribute to improved WUE and drought resilience in maize.

Main Methods:

• Evaluated hydrotropic response of seven maize varieties using a controlled moisture-gradient assay.
• Grew selected genotypes for five weeks under partial root-zone drying (PRD) and full irrigation in a greenhouse.
• Measured root distribution, shoot biomass, stem diameter, shoot water content, and water use efficiency (WUE).

Main Results:

• Significant genotypic differences in root hydrotropic behavior were observed.
• Strong hydrotropism did not solely guarantee shoot maintenance under PRD; one genotype showed reduced biomass despite strong hydrotropism.
• Genotypes with superior shoot water status, larger stem diameter, and higher shoot water content exhibited the highest WUE under PRD.

Conclusions:

• Root hydrotropism is a variable trait in maize and is associated with shoot traits and WUE under water deficit.
• The adaptive advantage of hydrotropism in drought conditions may be contingent upon complementary shoot characteristics.
• Developing drought-resilient maize requires breeding strategies that integrate strong root hydrotropism with enhanced shoot function under water stress.