Do you ever wonder how much water plants need?
Plants need up to 300 grams of water to make one gram of dry plant matter.
It doesn't have to be like that. There is a natural secret that could be used to help plants thrive and use less water.
Most plants are made up of water. The ideal amount of water for a gram of dry mass is four grams.
They need more water to grow. Plants need about 300 grams of water to produce a gram of dry mass.
Why does the amount of water needed for hydration differ from the amount needed for growth?
Almost all the water plants take up their water from the soil through their roots.
There are valves in the leaves of the plant. Plants need CO2 from the air to grow.
The moist inside of the leaf is exposed to the outside air. Water can leak out of the stomata when it's open.
The opening and closing of the stomata is thought to control the amount of water in a leaf.
We assumed that the air in small pockets inside the leaves was completely saturated with water vapor and that the relative humidity was very close to it.
If the air inside the leaf is saturated and the air outside is dry, the opening of the stomata will control how much water gets out.
The leaf has large quantities of water Vapor coming out of it for each molecule of Carbon dioxide that comes in.
We assumed the air in the leaves had a relative humidity of 100 percent.
Because water moves from more saturated places to less saturated places, we thought cells inside leaves wouldn't be able to sustain hydration if exposed to air with relative humidity less than 100 percent.
We didn't have a way to measure the relative humidity of the air inside leaves. This situation could be improved by a recently developed "hydrogel nanoreporter" that can be injected into leaves.
Over the past 15 years, we have found evidence that the assumption is not correct.
The relative humidity in the air spaces inside leaves fell to as low as 80 percent when the air outside was dry.
When the relative humidity inside the leaves decreased, photosynthesis did not stop or slow down.
Even as the air outside increased its "evaporative demand", the rate of water loss from the leaves remained the same.
If the leaves restricted their loss of water only by closing their stomata, we would expect the process to slow down or stop.
Plants can control water loss from their leaves by keeping the stomata open.
Plants are controlling the movement of water through the use of aquaporins, which reside in the cells inside the leaf, according to us.
We will conduct more experiments to see if aquaporins are the mechanism behind the behavior we observed.
It may be possible to target this mechanism and give agriculturalists plants that use water more efficiently.
Global warming will cause the atmosphere to become thirsty for water.
Nature may yet reveal secrets that can be harnessed to boost plant production.
The authors want to acknowledge the contributions of Graham Farquhar, Martin Canny and others.
Lucas Cernusak is an associate professor at James Cook University and Chin Wong is a visiting fellow.
Under a Creative Commons license, this article is re-posted. The original article is worth a read.
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