Question: Why do paddy rice do well in a flooded region?

Jacinta Nzilani answered on 17 Jul 2025:

Hey,
Rice (especially Oryza sativa) is naturally adapted to grow in waterlogged environments, making it ideal for cultivation in flooded paddies.

🔬 Key Adaptations & Scientific Mechanisms.

1. Internal Aeration via Aerenchyma.

Rice roots and stems develop aerenchyma, which are air-filled channels that allow oxygen to move from the leaves down to submerged roots. This keeps the roots alive even in oxygen-poor (hypoxic) soils.
The formation of aerenchyma increases under flooding, prompted by ethylene and reactive oxygen signaling, helping rice survive in saturated soil.

2. Flood-Tolerance Strategies: Escape or Quiescence

Some rice varieties (e.g., deepwater rice) use the escape strategy: rapid internode elongation triggered by ethylene and gibberellin hormones, forcing leaves above floodwaters.

Other varieties (like Swarna-Sub1) follow the quiescence strategy: growth is suppressed under flood using the SUB1A gene to conserve energy, allowing survival during complete submergence for up to two weeks .

3. Better Nutrient Availability & Weed Control

Flooding suppresses weeds most cannot survive submerged soils while rice thrives, reducing competition.

Waterlogged conditions improve nutrient availability (e.g., phosphorus, iron) and stabilize soil pH, benefiting rice growth.