Reproductive resilience but not root architecture underpins yield improvement under drought in maize

Area of Science:

• Agricultural Science
• Plant Physiology
• Genetics

Background:

• Maize (Zea mays L.) grain yield has tripled in the last century.
• Root systems architecture (RSA) was hypothesized to drive increased water and nutrient capture, contributing to yield gains.

Purpose of the Study:

• To investigate the relationship between changes in maize RSA, water uptake, and grain yield over time.
• To determine if altered RSA in modern maize hybrids contributes to increased crop water uptake or yield.

Main Methods:

• X-ray phenotyping in controlled environments to analyze root system characteristics of single cross (SX) and double cross (DX) hybrids.
• Field measurements of soil water extraction under varying densities and irrigation.
• Analysis of yield and yield components in relation to hybrid type and growing conditions.

Main Results:

• Both RSA and yield have changed with maize breeding, but crop water uptake remained constant.
• Single cross (SX) hybrids exhibited smaller root systems compared to double cross (DX) hybrids.
• No significant difference in soil water extraction was observed between SX and DX hybrids.
• SX hybrids demonstrated higher yield and yield components than DX hybrids across different densities and irrigation levels.

Conclusions:

• Changes in RSA are not the primary driver of increased water uptake in maize.
• Altered RSA in modern hybrids represents an adaptation to high-density planting, potentially improving resource allocation to reproductive parts.
• Future maize genetic gains may require integrated approaches considering root physiology, phenotyping, and overall crop production systems.