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Hydroponic Glossary Of Terms
Have you ever wondered what is involved in Hydroponic gardening? In order to understand how to use hydroponics for gardening you will need to understand the terminology of the various parts. You will notice that some of these terms are similar to regular gardening as well.
Calcium - A secondary macroelement which provides an important component of cell walls, participates in the maintenance of membrane permeability and structure, and it is also known to activate some enzymes. Symptoms of calcium deficiency include tip dieback of buds and new leaves.
Callus - A cluster of undifferentiated plant cells that have the capacity to regenerate a whole plant in some species.
Cambium - Layer of living cells between the wood and the innermost bark of a tree. Each growing season the cambium adds a new layer of cells (by cell division) on the wood already formed, as well as a layer of inner bark on the cambium's outer face. Division of these cells results in diameter growth of the tree through formation of wood cells (xylem) and inner bark (phloem).
Capillary action - Movement of water along microscopic channels. This movement is the result of two forces: the adhesion and absorption of water to the walls of the channels; and cohesion of water molecules to each other. When the surface of a liquid is in contact with a solid, the liquid is elevated or depressed depending upon the relative attraction of the molecules of the liquid for each other or for those of the solid. This is similar to how plants seemingly defy gravity when they transport liquid from the roots upward through the plant.
Carbohydrates - Starches and sugars manufactured by a plant and used to provide energy for metabolism, and structural compounds for growth.
Carbon - A major component of organic molecules, which are the building blocks of all organisms. Humans breath air, plants "breath" carbon dioxide. Carbon dioxide supplies the carbon necessary for plant health. Plants growing outdoors will not be deficient in carbon.
Carbon Dioxide - A greenhouse gas whose atmospheric concentrations have been continually increasing from its pre-industrial (1750-1800) levels of 280 parts per million (ppm). It is currently increasing at a rate of 1.3-1.6 ppm per year, with a concentration (1995) ranging from 356-360 ppm, depending on location. There is a natural seasonal cycle in carbon dioxide levels in the atmosphere; CO2 decreases in summertime when plant productivity consumes CO2, and an increase in winter when biota are less active and respiration exceeds photosynthesis.
Catalyst - A substance that increases the rate of a chemical reaction, without being consumed or produced by the reaction. Enzymes are catalysts for many biochemical reactions.
Causal agent - Any entity that causes events to happen. Example: Fungal infection causing Verticilium wilt. The fungus is the causal agent.
Cell - The basic structural and functional unit of all organisms; cells may exist as independent units of life, or may form colonies of tissues as in higher plants and animals.
Chelate - Organic chemical that forms ring compound in which a metal ion is held between two or more atoms strongly enough to diminish the rate at which it becomes fixed by soil, thereby making it more available for plant and microbial uptake.
Chlorophyll - The green pigment in plants that is created in the presence of light, which is necessary for photosynthesis to occur.
Chlorosis - The discoloration of normally green plant parts that can be caused by disease, lack of nutrients, or various air pollutants.
Citric Acid - An organic acid naturally occurring in citrus fruits used to adjust the pH of products, and nutrient solutions.
Cladosporium - any of several fungal diseases that afflict plants; commonly called leaf mold.
Clay - A very fine grained material, smaller than silt (clay has a diameter of less than 1/256 mm). Clay is formed by the weathering and breaking down of rocks and minerals.
Clone - A clone is a genetically identical group of plants derived and maintained from one individual by vegetative propagation.
Closed system - a hydroponic system, like nutrient film technique (NFT) systems, that recirculates the nutrient solution.
Coconut coir - Fiber made by cracking the outer brown husk of the coconut, shredding it into coarse fibers, then twisting or weaving them. Used for doormats, household brushes. Coconut coir is rot-resistant and naturally durable.
Cold frame - Cold frames are like small greenhouses, creating a microclimate around the plants inside. They serve to protect plants from frost or to harden-off seedlings in the spring. Any number of materials can be used, but generally, wood is used to create a box-like, open bottomed frame. A hinged lid can be opened to allow in air on hot days. The lid is made mostly of glass (or clear plastic) to allow in light. The soil is warmed by the sun during the day and then releases the heat into the confines of the cold frame at night, protecting the plants inside from freezing.
Companion planting - Some plants inhibit the growth of others nearby by releasing substances into the soil (called allelopathy). Other plants actually assist neighbours by fixing nitrogen or by repelling insects that attack them (oregano repels the cabbage butterfly for example). Gardeners can profit by being aware of these relationships.
Compost - Process whereby organic wastes, including food wastes, paper, and yard wastes, decompose naturally, resulting in a product rich in minerals. Compost is ideal for gardening and farming as a soil conditioner, mulch, resurfacing material, or landfill cover.
Compost tea - A water extract of compost that is brewed, usually in water. Organisms extracted from the compost, including bacteria, fungi, protozoa and nematodes are given a chance to increase in number and activity using the soluble food resources and nutrients present in the water. An enormous diversity of bacteria, fungi, protozoa and nematodes should be produced, depending on the quality of the compost.
Conductivity factor - A unit used in calculating fertilizer concentration. Example: 1 CF = 64 ppm (parts per million).
Conductivity - the scale, described as electrical conductivity (EC) or conductivity factor (CF), that is used to measure the strength of nutrient solution.
Convertible - (See Switchable)
Copper - One of the seven micronutrients essential for plant growth. It is a component of some enzymes and of vitamin A. Symptoms of copper deficiency include browning of leaf tips and chlorosis.
Corm - The bulblike underground part of a stem, as found on crocus or gladiolus.
Cotyledon - The "seed leaves" produced by a seed plant embryo. They serve to absorb nutrients packaged in the seed, until the seedling is able to produce its first true leaves and begin photosynthesis. The number of cotyledons is a key feature for the identification of the two major groups of flowering plants.
Cover crop - Cover crops will often include leguminous plants like clover and vetch, but they might also be grains like rye or oats. Cover crops are often planted as a green manure, but they also serve to prevent erosion, control weeds, and conserve water in the soil (from losses due to evaporation).
Cross-pollination - transferring pollen from the flowers of one plant of a species to the stigma of another plant of the same species.
Crown - The upper branches and leaves of a tree.
Cultivar - A cultivated variety of a plant selected for some feature that distinguishes it from the original species from which it was selected.
Cultivation - The process of preparing the land and caring for growing crops.
Cutting - (See Clone)
Cytokinin - Any of a class of plant hormones that promotes cell division and delays the senescence (aging) of leaves.
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