Really simple plant biology
Every gardener can benefit form a basic knowledge of plant biology.
For some, the phrases “plant biology” or “plant physiology” or even the word botany brings to mind scary images. Certainly these sciences can be very complex and studying them is reserved for the truly motivated or professional. But even "by the seat of their pants" gardeners can benefit from a small amount of such information, and it doesn't have to be difficult to absorb.
Hydroponics is essentially a branch of horticulture, the practice of cultivating plants. But before one can cultivate well it's essential to have some knowledge of the needs of plants. That's where botany proves its worth.
Plants, obviously, are living things. But they have important differences from animals. Chief among those is the ability to absorb nutrients and generate what they need. That is, a plant can absorb sunlight, which provides an energy source. At the same time, it can extract available chemical elements from the surrounding medium, then transform them into food for itself.
Animals, by contrast have to get their food from other sources, either other animals or plants. Sunlight provides them with warmth but not energy to power their functions. There are exceptions, as there are throughout biology. Some extremely small organisms that are sometimes thought of as animals can perform plant-like activities. That's what makes them borderline cases.
The primary mechanism that most plants use to perform those needed activities is photosynthesis. It can be represented by a simple chemical equation:
6CO2 + 12H2O + light = C6H12O6 + 6O2 + 6H2O
Six molecules of carbon dioxide (6CO2) and 12 molecules of water (12H2O) combine by using energy provided by light. The chemical reaction produces glucose (C6H12O6), a type of sugar. As with animals, the glucose is then later broken down to provide energy for various functions. As a “'side benefit” (to us, that is) six molecules of oxygen (6O2) and six of water (6H2O) are given off.
That relatively simple chemical reaction allows plants to be self-sufficient. They take in available energy, pull nutrients from the surrounding and produce their own energy and food. It would be great if humans could do the same!
But there's much more to the plant's life than just energy production and food consumption. In order to perform those functions plants have to be sturdy and to breathe.
In order to carry out essential processes, the plant has to have a stable structure. Since hydroponics is soil-less, that support has to come from something. Externally it's supplied by the medium by either supporting trays, strings, rockwool, etc. Internally, the plant's own cells provide that support, using available elements.
Calcium, for example, plays a large role in forming cell walls. Those eventually build up into tissues that form different types and make features that stand up to gravity, wind and other forces.
Plants, like animals, perform a kind of respiration - breathing. Many of us are taught in elementary school that plants take in carbon dioxide and give off oxygen. That's true. But they also consume oxygen. They simply give off more than they consume.
They don't have lungs, but they do have stoma (pores or holes) that allow them to take in CO2 and oxygen and expel some of the O2. That process is called cellular respiration and it's essential to root growth.
These are only a few of the many fascinating features of plants that give them the ability to provide food, beauty and delightful smells to their fortunate caretakers: hydroponic gardeners.