Yes, CAM plants release oxygen at night.
CAM (Crassulacean Acid Metabolism) plants exhibit a unique photosynthetic adaptation that allows them to thrive in arid environments, such as deserts, or in situations where water conservation is critical, like epiphytic lifestyles (plants that grow on other plants).
Unlike most plants that open their stomata (pores on leaves) during the day to take in carbon dioxide (CO2) for photosynthesis, CAM plants do the opposite.
The CAM Pathway at Night
- Stomata Behavior: CAM plants keep their stomata closed during the day to minimize water loss through transpiration.
- CO2 Fixation: At night, when temperatures are cooler and humidity is higher, CAM plants open their stomata.
- Carbon Uptake: They take in CO2 and fix it into organic acids, primarily malate, which is stored in vacuoles.
- Oxygen Release: According to the provided reference, during this nighttime period when they open stomata to fix CO2, CAM plants also "releases O2". This suggests that some part of the oxygen-producing process is occurring or released at this time, contrary to the typical understanding that oxygen is primarily a byproduct of the light-dependent reactions which happen during the day. The reference explicitly states: "CAM pathway... keep their stomata closed during day and open it during night for fix CO2 in the form of malate and releases O2."
Why This Adaptation is Crucial
This nighttime CO2 uptake strategy is a key adaptation for survival in harsh, dry conditions. By fixing CO2 at night when water loss is minimal, CAM plants can conserve precious water during the hot, dry daytime.
Day vs. Night in CAM Plants
Here's a simplified view:
| Process | Day | Night |
|---|---|---|
| Stomata | Closed (Water Conservation) | Open (CO2 Uptake, According to reference: O2 Release) |
| CO2 Fixation | Minimal (stomata closed) | Active (CO2 fixed into malate) |
| Light Reactions | Active (if light available, producing ATP/NADPH) | Inactive (No light) |
| Calvin Cycle | Active (using stored CO2 from malate) | Inactive |
| Oxygen Release | Primary release period (from light reactions) | Yes, according to the provided reference |
While the primary release of oxygen from photosynthesis typically occurs during the day when the light-dependent reactions split water, the provided reference indicates that CAM plants "releases O2" at night when their stomata are open for CO2 fixation.
