Symptoms
The leaves of the deficient plant are erected and dark green. Older leaves turn brown and die. Red and purple tints may develop in some varieties.
Reasons
Phosphorus deficiency.
Susceptibility to P deficiency varies among rice cultivars.
Soils particularly prone to P deficiency:
- Coarse-textured soils containing small amounts of organic matter and small P reserves (e.g. sandy soils in northeast Thailand)
- Acid sulfate soils in which large amounts of active Al and Fe result in the formation of insoluble P compounds at low pH.
