Reduced root cortical burden improves growth and grain yield under low phosphorus availability in maize

Area of Science:

• Plant Biology
• Agricultural Science
• Root Physiology

Background:

• Low phosphorus availability is a major constraint on crop productivity worldwide.
• Root architecture and metabolic efficiency are critical for nutrient acquisition.
• Living cortical area (LCA) represents a significant metabolic cost for plants.

Purpose of the Study:

• To test if reduced LCA improves maize growth and phosphorus capture under low phosphorus.
• To investigate the relationship between LCA, soil exploration, and yield.
• To identify root traits conferring adaptation to phosphorus-limited environments.

Main Methods:

• Maize genotypes with contrasting LCA were grown in field and greenhouse conditions.
• Phosphorus availability was manipulated (optimal and suboptimal regimes).
• Root traits, respiration, biomass, phosphorus content, and grain yield were measured.

Main Results:

• Reduced LCA (by 0.2 mm²) significantly decreased root respiration and increased root depth and biomass under low phosphorus.
• Plants with lower LCA allocated more roots to deeper soil layers and showed higher grain yield.
• Lower arbuscular mycorrhizal colonization in low-LCA plants was not correlated with biomass or phosphorus content.

Conclusions:

• Root phenes that reduce metabolic cost, such as decreased LCA, are adaptive under phosphorus stress.
• Cortical cell file number and size are important determinants of biomass and phosphorus content in low-P conditions.
• Targeting root traits like LCA offers a promising strategy for improving crop performance in phosphorus-deficient soils.