However, there is a wide range of water use efficiency in each type based on species. Through evaporative cooling , plant transpiration brings down the temperature of leaves, the largest plant organ.
Water balance in plants is also maintained by transpiration. Plants absorb a lot of water and transpiration is a means by which excess water is removed. Much of the water uptake is used for photosynthesis, cell expansion, and growth, but a single tree that is 20 meters high can take up between 10 liters to liters daily, depending on its species. Euperua purpurea, an Amazonian overstory tree, absorbs 1, kg day-1, and even a simple corn plant can absorb liters in the summer. Turgor pressure keeps the plant cells full and turgid, due to the transpiration stream of water from roots to shoots.
This has many uses for plants:. Transpiration is an important component of the global water cycle. The amount of water that is lost by plants is great enough to influence the atmosphere.
Transpiration along with evaporation is called evapotranspiration. The contribution of transpiration to evapotranspiration is a hotly debated topic. Differences in transpiration can be attributed to geographic location, season, time of day, and cloud cover.
Anthropogenic activities resulting in increased carbon dioxide levels, land use, deforestation, and climate change also alter the transpiration rate. Higher temperatures due to climate change are speeding up evapotranspiration. This increases the amount of water vapor in the atmosphere, leading to more intense and frequent rains in some places, especially in coastal areas.
Colder regions are experiencing warmer and longer growing periods, which also produces higher levels of transpiration. With added pressure from climate change, measuring transpiration is becoming an important part of many disciplines, including the following:. The increased role that transpiration plays requires the use of devices that can give precise, rapid results. To allow for in situ measurements, tools also have to be portable and small.
With the help of this new technology, it is possible to utilize plant-scale transpiration measurements to aid global needs. Ecology and Environmental Science, B. What is solute potential? What are some examples of plant transport? How does xylem affect turgor pressure?
What is an apoplast? What is a casparian strip made of? When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf.
This process is called transpiration. Water is drawn from the cells in the xylem to replace that which has been lost from the leaves. Water molecules inside the xylem cells are strongly attracted to each other. There is strong cohesion between the molecules because of hydrogen bonding. A continuous column of water is therefore pulled up the stem in the transpiration stream by evaporation from the leaves.
As water travels through the xylem in the stem and leaf, it is being replaced by water taken up by the roots. When the roots take in water from the topsoil layer, the water is then converted into vapour and is essentially evaporating off the surface of the leaves. The stomata open for two reasons; to absorb carbon dioxide CO 2 from the atmosphere and to take in sunlight , this encourages photosynthesis.
Stomata close in events such as drought to prevent the loss of water and eventual death of the plant. The rate at which transpiration occurs is varied based on temperature , air movement such as wind , how much moisture is in the soil and surrounding air, the type of plant and land use.
Lyndon G.
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