Root Respiration Curves

What root respiration is

Root respiration is the metabolic process by which roots consume oxygen to generate energy.

Respiration rate varies with: - Temperature - Root age - Oxygen availability - Plant growth stage

General behaviour

• Low temperatures → low respiration demand
• Optimal range → efficient energy use
• High temperatures → sharply rising oxygen demand
• Oxygen limitation → rapid stress and dysfunction

Stress threshold

Once oxygen supply cannot meet respiration demand: - Energy production falls - Nutrient uptake slows - Root tissue degrades - Secondary stress symptoms appear in shoots

Diagnostic importance

Respiration curves explain why: - Symptoms appear suddenly - Stress worsens rapidly once thresholds are crossed - Recovery is slow after oxygen deprivation

Key concept

Roots fail non-linearly — gradual stress leads to sudden collapse.