Among the vital processes for plant growth is photosynthesis. Whether it's outdoor cultivation or indoor, without this biochemical process, a plant would not be able to survive.
Have you ever wondered how plants feed and grow strong, healthy, and lush? It's all thanks to the complex chlorophyll synthesis mechanism.
Plant species are organisms called "autotrophs" (from the Greek autòs "self" and trophéo, "nourish"). This means they obtain their own nourishment from inorganic materials like air, water, and sunlight.
In this manual, we will explain in detail what photosynthesis is and provide you with an exhaustive explanation of how it works and why it is so important for getting a better yield from your plants.
Keep reading.
What is Photosynthesis
Photosynthesis is a chemical process through which plants produce organic substances (mainly carbohydrates) with:
- Carbon dioxide;
- Metabolic water;
- Sunlight.
The various chemical reactions that form photosynthesis fall under the anabolic processes of carbohydrates and are entirely opposite to the inverse processes of catabolism (oxidation).
It is a vital biochemical process for the health and survival of plants. Through this, plant species produce the nourishment needed to meet their growth needs.
At the heart of this entire process is chlorophyll, the pigment found on the surface of leaves, responsible for their green color.
The chlorophyll molecules present in plants (A and B) are photosensitive, meaning they can interact with sunlight at different wavelengths, from 400 nm (blue) to 700 nm (red), converting it into chemical energy.
This energy is then used to transform the carbon dioxide absorbed from the air into sugars and carbohydrates, which are essential nutrients for the plants themselves, releasing oxygen as a byproduct of the entire photosynthesis process.
This is why it is also called "oxygenic photosynthesis", as it releases oxygen, an equally essential element for life on planet Earth.
Let's see in the next section how exactly Photosynthesis happens.
How Chlorophyll Synthesis Works: Diagram and Stages
The photosynthesis process is the primary producer of organic compounds from inorganic substances on Earth and is undoubtedly the first form of anabolic process supported by living organisms.
The components of this process come from carbon dioxide and water. To understand it better, we need to analyze the chemical formula of photosynthesis:
6CO2 + 6H2O = C6H12O6 + 6O2
In essence, while photosynthesis in plants takes place inside chloroplasts (small organelles containing chlorophyll that absorb sunlight), six molecules of CO2 and six molecules of H2O are converted into one molecule of glucose (C6H12O6), an essential sugar for plants.
As a byproduct, photosynthesis produces 6 molecules of oxygen, which the plant releases into the environment through stomata (small pores) on the leaves.
Photosynthesis occurs in two distinct phases:
- Light (or light-dependent), meaning in the presence of light;
- Dark, the carbon fixation phase, independent of light.
In the light phase, raw sap - made up of mineral salts and water - moves from the roots to the leaves, acting like "solar panels" for the plants, absorbing light through the chlorophyll. Let's explain the entire process more clearly.
The photosynthetic function occurs inside chloroplasts, which contain a system of membranes (called thylakoids) and some connecting lamellae (intergranular lamellae), where chlorophyll molecules are located, grouped to form photosystems.
Photosystems are composed of a combination of molecules and pigments arranged to enclose a particular chlorophyll molecule called a "trap". The photon's force is transferred from molecule to molecule until it reaches the special chlorophyll.
Let's clarify: it's possible to distinguish between photosystem I and photosystem II. In the first, the trap molecule is excited at a wavelength of 700 nm, while in the second, it is excited at 680 nm.
These molecules can all capture light energy, but only those of chlorophyll A can reach an excited state that triggers the photosynthetic reaction. In contrast, the molecules used for capturing are called antenna molecules.
The light phase is dependent on chlorophyll A, which absorbs only the red, blue, and violet light spectrum. The energy absorbed by chlorophyll molecules promotes the transformation of electrons from lower-energy atomic orbitals to higher-energy orbitals.
These are exchanged through a water molecule splitting, releasing two protons, two electrons, and one oxygen molecule through photolysis, driven by the OEC (oxygen evolving complex), an oxygen-evolving complex associated with photosystem II.
The electrons emitted by chlorophyll from photosystem II are inserted into an electron transport chain formed by the cytochrome, which loses energy in the process, transforming and assuming lower energy. The energy dissipated is used to push protons from the stroma into the thylakoid, creating a proton gradient.
In total, the energy produced throughout the process is in the form of ATP and NADPH2, two chemical compounds that store and distribute energy to all parts of the plant.
The second phase, also known as the Calvin Cycle, allows for the transformation of inorganic carbon (found in carbon dioxide) into organic carbon (glucose).
This phase is erroneously referred to as the "Dark Phase" because it does not refer to a complete absence of light. Furthermore, the enzymes involved in this phase are activated by light, which is why it occurs simultaneously with the light phase and not at night.
In fact, during the night, there is a shortage of ATP and NADPH, which are produced during the day, and the stomata are closed, preventing carbon dioxide from entering. Furthermore, the various enzymes involved are inactive at night, as they are light-dependent.
Now that you have a clearer understanding of how the photosynthesis process works, let's explore in the next section why it's so important.
Why Is the Photosynthesis Process Essential?
The glucose synthesized during this process is essential for two main reasons:
- It plays a role in synthesizing high-energy molecules;
- It provides energy for the various metabolic processes of the plants.
This explains why it is so important: without glucose production, plants wouldn't have the adequate nourishment to survive and carry out all the processes involved in their growth.
The byproduct of this process is oxygen, a vital substance for the survival of all living beings on Earth. Thus, plants absorb carbon dioxide from the atmosphere, which is converted into oxygen through photosynthesis.
This also explains why plants are valuable allies in the fight against environmental pollution and why growing deforestation raises concerns for the future of humanity.
How to Boost Photosynthesis in Your Indoor Cultivation
Even in indoor cultivation, light is a fundamental element in enhancing the photosynthetic process and producing vital energy for plants. Therefore, what you need to do is install an adequate and efficient lighting system to maximize the photosynthesis rate.
How should indoor lights be? The elements you need to consider for effective photosynthesis are:
- Light intensity;
- Wattage;
- PAR;
- Light spectrum suited to the plant growth phase;
- Ambient temperature;
- Hours of light exposure.
Grow lights – whether MH, HPS, or AGRO – are characterized by brightness, which is measured in lumens. Each plant requires a certain level of light intensity, around 10,000-15,000 lux, to activate photosynthesis.
In addition to lux, it's important to know the PAR (photosynthetically active radiation), which measures a lamp's growth power. The range between 400 and 700 nm is used by most plants for their photosynthesis.
The unit of measurement for PAR is PPFD (photosynthetic photon flux density), which indicates how many photons in the PAR range hit the plant's leaves per second.
To learn about the ideal light for photosynthesis, check out our guide on the light spectrum for plants.
When purchasing grow lights, you should always pay attention to power: if the wattage is too low, the light source won't emit enough light for optimal crop development. The ideal range is between 400-600 W/m².
Grow lights must also have a specific light spectrum, rich in blue tones (ultraviolet) and red tones (infrared), to be adjusted based on the plant's vegetative phase.
In general, without forgetting the specific needs of each plant variety, temperatures that are too high or too low can impair photosynthesis. The ideal peak is between 25°C and 30°C.
The photosynthesis process requires hours of light but also hours of darkness. That's why you should equip yourself with a control panel with a timer and set lighting cycles based on the needs of the cultivated plants. Generally, 18 hours of light is optimal during the vegetative phase, while a 12-hour light cycle is perfect for stimulating flowering.
While the right lights are important, so are growing equipment and products. Check out our basic and professional indoor cultivation kits.
Each kit is designed to meet the needs of growers and offer only the best for maximum plant yield and high-quality flowering with minimal effort.
Choose your favorite and purchase directly online at Grow Shop Italia.
