Part of the plant where photosynthesis generally occurs

Photosynthesis is the light-powered key to unlocking plant growth and quality.

This process by which all plants convert light energy into chemical energy that’s then used to drive different metabolic processes is critical to the success of a crop, and without the right levels of light plants can yellow, droop, drop leaves, or fail to grow properly.

For growers, it is critical to ensure that lighting is managed perfectly to avoid the issues that poor photosynthesis can cause. Which makes it relatively important to understand where photosynthesis takes place so that you can invest in the correct light sources, and ensure they are correctly placed.

Photosynthesis: The Basics

The primary cellular structures that ensure photosynthesis takes place are chloroplasts, thylakoids and chlorophyll. Photosynthesis takes place inside the chloroplasts that sit in the mesophyll of the leaves. The thylakoids sit inside the chloroplast and they contain chlorophyll which absorbs the different colours of the light spectrum to create energy (Source: Biology: LibreTexts). Now this is where things get interesting – the impact that different light wavelengths have on photosynthesis.

Photosynthesis in numbers.

The surface of the leaf absorbs the blue and red wavelengths while the green light is absorbed deeper within the plant. This light is what’s absorbed by the chloroplasts and is most effective in photosynthesis and the conversion of energy. All the visible wavelengths are absorbed, to some extent, by the leaf, but red, blue and green are the most important for photosynthesis. The light spectrum used by plants is known as Photosynthetic Active Radiation (PAR) which defines light spectrum as well as the levels of solar radiation that sit between 400 and 700 nm.

Photosynthesis: The Inside

Photosynthesis primarily takes place in the leaves, with a smaller amount in the stems, and has both a light independent and light dependent process. The light dependent process takes the light that has been absorbed by the thylakoids and turns it into chemical energy and this then is used to turn the CO2 absorbed by the leaves into carbohydrates which forms the light independent part of the process. The entire cycle, known as the Calvin Cycle, creates the by-products of glucose and oxygen, the former used by the plant, the latter released into the atmosphere.

To ensure that photosynthesis is optimised, growers need to invest into lights that emit the right levels of PAR radiation at the right intensity, which means they have to work with grow lights that are designed to produce the correct colour spectrum and that are correctly placed. It’s important to note that plants can be damaged if the light intensity is too extreme – photosynthesis takes place at a set level, beyond a certain point it flattens out or decreases which means additional lighting won’t necessarily boost the process and can negatively impact on plant health.

In addition to considering light intensity and quality, you will need to balance light timings to ensure that the plant is receiving a mix of ‘day’ and ‘night’ light, and the temperature of the grow space. Plants need to undergo the process of photoperiodism in order to flower or reach specific stages of the growth cycle, and they can’t grow in conditions that are too hot or too cold.

It’s worth working with a company that understands the full impact of grow lighting on your plants and can help you implement a grow light layout and design that takes all these factors into consideration. Light Science Technologies has in-depth understanding of the technology, the science, and how to support you in achieving the correct light, heat and distance so your plants can photosynthesise and grow.