Plant Physiology & Development
Leaf Senescence & Nutrient Remobilization
Leaf senescence is a regulated developmental process that dismantles cellular machinery and remobilizes useful compounds before tissue death. Stress can accelerate senescence, while normal aging can resemble nutrient or root-zone problems if location and progression are ignored.
Key concepts
- Senescence involves ordered changes in chlorophyll, proteins, membranes, and nutrient transport
- Older leaves often enter senescence before younger source leaves
- Nitrogen and other mobile resources can be remobilized from aging tissue
- Stress-induced senescence can overlap visually with normal developmental aging
- Whole-plant source–sink relationships change as reproductive demand increases
What to measure or observe
- Map which leaves yellow first and whether the pattern is symmetrical
- Record plant stage and flowering progression
- Compare senescence with root-zone EC, pH, moisture, and disease observations
- Track whether yellowing progresses into younger tissue
- Document leaf loss and canopy light exposure over time
Common mistakes
- Calling all late-cycle yellowing a deficiency
- Calling all yellowing normal senescence
- Ignoring root disease because the plant is in flower
- Removing large amounts of aging foliage before checking what the pattern means
- Using calendar week as the only maturity context
Visuals this lesson still needs
- Normal senescence progression plate
- Senescence versus root-stress differential
- Nutrient remobilization flow diagram
- Old-to-young leaf progression map