How light enables plants to feed the world

How light enables plants to feed the world

During these short winter days, I think it’s important to remember how important is adequate light to plants – and for all of us.

Sunlight is the base for life on Earth, because it enables photosynthesis. Because of it, animals get oxygen to breathe and plants to eat. Only plants (and some algae) can photosynthesize, or convert light energy into chemical energy. Even though plants may seem passive, inside every leaf there is a complex but extremely efficient process in function all day long. Plants build themselves with carbon dioxide, water and nutrients using energy from light, either sunlight or artificial light. During that process, plants also produce oxygen. This is used by animals who produce carbon dioxide, which plants’ leaves then take from the air and use in photosynthesis.

The complicated process

Photosynthesis is an awfully complicated process, which happens in chloroplasts inside leaf cells. Much simplified it happens like this: using the power from light absorbed by the chloroplasts, the plant breaks down water to hydrogen and oxygen, which it releases to the air, and builds sugars from carbon dioxide. About half of the sugars are consumed as fuel in the plant’s own vital functions. With the sugars left, the plant builds starch and cellulose which are the plant’s energy stores.

It’s estimated that the photosynthesis produces about 160 billion tons of carbon hydrates each year. No other chemical process produces such amounts of material on the Earth. Additionally, the resources of coal, oil and natural gas are made up of ancient plants. Storing radiant energy to chemical energy requires many phases. This is why photosynthesis is such a complex process.

The research on photosynthesis has progressed tremendously during the 1900s, but still we don’t know everything about the process. If scientists could mimic the usage of light energy to break down water to oxygen and hydrogen, as it happens in photosynthesis, all of the energy problems of the mankind would be resolved. Thanks to the rigorous research on photosynthesis, it may be possible in the future to develop hydrogen-based applications for power production.

Measuring light

Of all the sunlight’s spectrums, the plants only use about 37 %. In the photosynthesis the plants use especially the blue and red parts of the light spectrum as their energy source, since the chloroplasts absorb those wavelengths. Much of the other colours are reflected away, and of those the human eye is most sensible to green. That’s why plants appear green to us.

The only way to measure whether the light source gives enough usable light to the plants is PAR (Photosynthetically Active Radiation). It designates the spectral range from 400 to 700 nanometres that plants are able to use in the process of photosynthesis. PAR is normally quantified as µmol/m2/s.

In Plantui Smart Garden the spectrums and capacity are adjusted to suit perfectly the plant’s needs. Thanks to led technology, the energy consumption is a low as 60 kWh per year.