Water Transport Pathway in Roots
Nitrogen Cycle: Bacterial Steps
Root Cross-Section — Casparian Strip
Image: Cross-section of a plant root showing the Casparian strip (suberin band, yellow) in the endodermal cells that blocks the apoplast pathway. Source: Wikimedia Commons (public domain).
Transpiration Routes — Quick Table
| Route | Pathway | Percentage | Regulated? |
|---|---|---|---|
| Stomatal | Stomatal pores via guard cells | 90–95% | Yes — / ABA |
| Cuticular | Waxy cuticle surface | 5–10% | Partially (cuticle thickness) |
| Lenticular | Lenticels in bark | <1% | No |
Element Mobility and Deficiency Location
| Mobility | Elements | Deficiency Location | Example Symptom |
|---|---|---|---|
| Mobile | N, P, K, Mg | Older (lower) leaves first | Chlorosis of old leaves (N); purple old leaves (P) |
| Immobile | Ca, Fe, S, Mn, B | Younger (upper) leaves / meristems first | Necrosis of shoot tips (Ca); interveinal chlorosis young leaves (Fe) |