Respiration
/ˌrɛspəˈreɪʃən/
Definition
Respiration is the metabolic process in plant cells that breaks down sugars, usually using oxygen, to release usable energy. It occurs day and night in all living tissues, especially growing roots, shoots, and seeds. Unlike photosynthesis, it does not make sugar from light; it consumes stored or newly made carbohydrates and produces carbon dioxide, water, and energy that powers growth, repair, and transport within the plant.
Biological Role
- Energy for active cells: In plants, respiration supplies usable energy for cell division, root growth, flowering, fruit development, and the repair of damaged tissues. Fast-growing parts often have especially high rates.
- Day and night activity: Unlike photosynthesis, respiration continues in both light and darkness. This is why plants still use stored sugars at night to support maintenance and ongoing growth.
- Temperature and oxygen link: The rate usually rises as temperature increases, up to the plant’s tolerance range. Poorly aerated soils can limit oxygen around roots, reducing root respiration and weakening water and nutrient uptake.
- Post-harvest changes: After harvest, fruits, vegetables, bulbs, and cut flowers keep respiring. Higher rates use stored carbohydrates more quickly, which can shorten storage life and speed aging or quality loss.
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