Do plants respire at night?
Written by
Paul Reynolds
Reviewed by
Prof. Martin Thorne, Ph.D.Plants respire nonstop around the clock, day and night. Their vital processes continuously convert sugars into energy 24 hours a day, utilizing oxygen. The evening respiration rate is apparent because photosynthesis ceases here. The rate of respiration is usually 20-30% higher at night because of the accumulation of sugars in the leaves, which are produced in the daytime, and the cooler temperature of the night. Some plants belong to the Crassulacean family, such as cacti, which appear to restrict their respiratory movement entirely to nighttime.
Daytime Respiration
- Occurs continuously alongside photosynthesis
- CO₂ release masked by photosynthetic absorption
- Uses freshly produced photosynthates for energy
- Typically 10-20% lower than nighttime rates
Nighttime Respiration
- Becomes clearly measurable without photosynthesis
- Rates increase due to sugar accumulation
- Prioritizes cellular maintenance and repair
- Cooler temperatures slightly slow enzymatic activity
CAM Plant Exception
- Open stomata exclusively during darkness
- Absorb CO₂ at night for daytime processing
- Water conservation adaptation for arid climates
- Examples: cacti, pineapples, and agaves
Respiration rates increase at night due to several factors. Cooler temperatures mean less risk of overheating stress. The excess sugar produced during daytime photosynthesis provides ample fuel for the plant. Energy at night is redirected toward helping with tissue repair. These cycles of resource use are patterns that facilitate maximum efficiency across day and night cycles.
Gardeners see respiration in practical evidence. Dew on leaves in the morning indicates water that has been given off during the night. Young leaves are growing faster if the night temperature is above 15° C. Yellowing of the leaves indicates that root respiration is poor due to packed soil. This evidence will aid in establishing the right care.
Respiration patterns significantly impact ecosystems worldwide. In particular, forests release large amounts of carbon dioxide at night. This is part of the natural carbon cycle. Climate change is enhancing the emissions of respiration due to warmer nighttime temperatures. A better understanding of these rhythms will allow us to predict environmental changes.
Read the full article: Respiration in Plants: The Complete Process Guide
