Respiration in Roots
Roots, The underground part of the plants, absorbs air from the air gaps/spaces found between the soil particles. Hence, absorbed oxygen through roots is utilized to liberate the energy that in the future, is used to transport salts and minerals from the soil.
We know that plants possess a specific ability to synthesize their own food through photosynthesis. Photosynthesis takes place in only those parts of the plants which have chlorophyll, the green plant parts. Photosynthesis is so evident that at times it seems to mask the respiratory process in plants. Respiration must not be mistaken for photosynthesis. Respiration occurs all through the day, but the photosynthesis process occurs in the daytime, in the presence of sunlight only. Consequently, respiration becomes evident at night time in plants.
This is the reason we often hear people warn against sleeping under a tree during nighttime, as it may lead to suffocation due to excess amounts of carbon dioxide liberated by trees following respiration.