溶解氧 (DO) 是指溶解在营养液中并可供植物根系使用的氧气 (O₂) 浓度。根需要氧气进行有氧呼吸——这个过程会产生养分吸收和生长所需的能量。在涝渍或停滞的系统中，溶解氧会迅速耗尽，迫使根系进行无氧呼吸，从而产生乙醇，损害根细胞，并为根腐病病原体创造有利条件。
关键事实
- Optimal dissolved oxygen level: 6–8 mg/L (ppm) for most hydroponic crops
- DO decreases as water temperature rises — cold water holds more oxygen
- Air stones and air pumps are the primary method for maintaining DO in reservoir systems
- Water falls, cascades, and spray nozzles also oxygenate solution through surface agitation
- Anaerobic conditions (low DO) are the primary cause of root rot (Pythium) outbreaks
- DWC systems are particularly susceptible to DO crashes if air pumps fail