BASIC PLANT BIOLOGY
1 - Basic plant anatomy and function
roots
Roots absorb water and minerals from the soil. Tiny root hairs stick out of the root, helping the absorption process. Roots help to anchor the plant in the soil, preventing it from falling over. Roots also store extra food for future use. Roots in soil-less culture show interesting differences from standard in-ground plants. In soil-less culture, water and nutrients are constantly supplied to the plants, which are facilitated in their nutrient search and can grow faster. Root growth in hydroponics can be significant for the intense uptake and the optimal delivery of phosphorus that stimulates their growth. It is worth noting that roots retain almost 90 percent of the metals absorbed by the plants, which include iron, zinc and other useful micronutrients.
stems
Stems are the main support structure of the plant. They also act as the plant’s plumbing system, conducting water and nutrients from the roots to other parts of the plant, while also transporting food from the leaves to other areas. Stems can be herbaceous, like the bendable stem of a daisy, or woody, like the trunk of an oak tree.
leaves
Most of the food in a plant is produced in the leaves. Leaves are designed to capture sunlight, which the plant then uses to make food through a process called photosynthesis. Leaves are also important for the transpiration of water.
flowers
Flowers are the reproductive part of most plants. Flowers contain pollen and tiny eggs called ovules. After pollination of the flower and fertilization of the ovule, the ovule develops into a fruit. In soil-less techniques, the prompt delivery of potassium before flowering can help plants to have better fruit settings.
fruits & seeds
Fruits are developed parts of flower ovaries that contain seeds. Fruits include apples, lemons, and pomegranates, but also include tomatoes, eggplants, corn kernels and cucumbers. The latter are considered fruits in a botanical sense because they contain seeds, though in a culinary definition they are often referred to as vegetables. Seeds are the reproductive structures of plants, and fruits serve to help disseminate these seeds. Fruiting plants have different nutrient requirements than leafy green vegetables, especially requiring more potassium and phosphorous.
1.2 - photosynthesis
All green plants are designed to generate their own food using the process of photosynthesis. Photosynthesis requires oxygen, carbon dioxide, water and light. Within the plant are small organelles called chloroplasts that contain chlorophyll, an enzyme that uses the energy from sunlight to break apart atmospheric carbon dioxide (CO2) and create high-energy sugar molecules such as glucose. Essential to this process is water (H2O). This process releases oxygen (O2), and is historically responsible for all of the oxygen in the atmosphere. Once created, the sugar molecules are transported throughout the plant and used later for all of the physiological processes such as growth, reproduction and metabolism. At night, plants use these same sugars, as well as oxygen, to generate the energy needed for growth. This process is called respiration. It is vital to locate an aquaponic unit in a place where each plant will have access to sunlight. This ensures adequate energy for photosynthesis. Water should always be available to the roots through the system. Carbon dioxide is freely available from the atmosphere, although in very intensive indoor culture it is possible that plants use all of the carbon dioxide in the enclosed area and require ventilation.