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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.
Damping off - Any of a number of fungal diseases which attack seedlings, causing the stem to wither at the soil line, collapsing the whole plant. There is no good cure for affected plants, but removing all the diseased material and moving the seedlings to a warm, bright, airy location can save any remaining plants. Proper thinning and avoidance of over watering, especially during cloudy periods is the best preventive measure.
Dark reactions - A process found in all plants and animals: A series of enzymatic reactions in mitochondria involving oxidative metabolism of acetyl compounds (sugars made during photosynthesis) to produce high-energy phosphate compounds that are the source of cellular energy.
Day length - The duration of lighting cycle where there is enough light to perform photosynthesis. Example: For an 18 hour on and 6 hour off lighting cycle, the day length equals 18 hours.
Day neutral plants - Plants that flower regardless of day length.
Deficiency - A sub-optimal level of either one or more nutrients, often resulting in poor health.
Deficiency. See mineral deficiency.
Desiccate - A process that loses water or moisture.
Dicot - A subdivision of flowering plants whose members possess two embryonic seed leaves, or cotyledons.
Dioecious - varieties or species with male and female flowers on separate plants.
Disease - Any condition that interrupts normal plant physiology that is caused by irritation by a primary causal agent that results in the formation of symptoms.
Dominant - A heritable character possessed by one parent of a hybrid which, when pure, will express itself in the hybrid to the apparent exclusion of the opposite or recessive character in the other parent. Also, a species that comprises the majority of biota in an ecosystem.
Dormancy - The resting or inactive phase of plants or seeds. Dormancy of shoots is usually in response to unfavorable environmental conditions. The breaking of seed dormancy requires moisture, sometimes cold temperatures and/or abrasion of the seed coat.
Downy mildew - Any of various fungi of the family Peronosporaceae parasitic on grapes, potatoes, and melons.
Drip irrigation - An irrigation method where pipes or tubes filled with water slowly drip onto a landscaped or other planted area. Drip irrigation is a low-pressure method of irrigation and less water is lost due to evaporation than high-pressure spray irrigation.
Dry rot. (See Fusarium.)
Early blight - Early blight is a very common disease of both potato and tomato. It causes leaf spots and tuber blight on potato, and leaf spots, fruit rot and stem lesions on tomato. The disease can occur over a wide range of climatic conditions and can be very destructive if left uncontrolled, often resulting in complete defoliation of plants. In contrast to the name, early blight rarely develops "early", but usually appears on mature foliage.
Ebb and Flow - A type of hydroponic system where potted plants are held in a tray, which is periodically flooded with a nutrient solution and then drained.
Electrical Conductivity - Measure of the total concentration of dissolved salts in the water. When salts dissolve in water they give off electrically charged ions, these ions conduct electricity.
Electrical conductivity. See conductivity.
Embryo - An animal or plant in the early stages of its development; in plants, the stage in the seed before the beginning of rapid growth.
Emulsion - A suspension of droplets of one liquid in another liquid (such as oil and water). The two liquids do not actually combine but are instead suspended within one another.
Enzyme - A protein that acts as a catalyst, speeding the rate at which a biochemical reaction proceeds, but not altering the direction or nature of the reaction. Enzymes aren't consumed in the reaction.
Epinasty - That state in which more rapid growth on one side of a plant organ or part (especially leaf) causes it to bend or curl downward, typically a symptom of certain viral diseases.
Ethylene - A plant growth-regulating gas, naturally produced in ripening fruit as well as other parts of the plant, responsible for promoting ripening and involved in abscission and other plant processes.
Etiolation - The act of causing a plant to develop without chlorophyll by growing it without exposure to sunlight.
Expanded clay - A media that is composed of small clay beads, which are fired to 1,600 °F so they are sterile by way of the manufacturing process. They can easily be cleaned and reused.
F1, F2, F3, etc. - the F1 generation is the result of crossing two different varieties; a cross of two F1 plants produces F2 seed; and so on.
Fatty acids - Most common form of lipids found in all cells. Come in saturated (reduced) and unsaturated (oxidized) form and are a component of phospholipids and fats. Plants have the ability to breakdown fatty acids for needed energy.
Filament - see stalk.
Fish emulsion - (see Emulsion)
Flood and Drain - (See Ebb and Flow)
Flower - The flower is the reproductive organ of the plant. It contains both the female and male parts, but some are incomplete, having only one or the other.
Fluorescent light - A glass tube filled with a mixture of gases at low pressure. Emits ultra-violet radiation converted to light by the fluorescent coating inside the tube. A flourscent lamp is energy efficient.
Foliar feeding - Fertilization of a plant through its leaves by use of a water-soluble fertilizer sprayed directly onto them.
Frost free date - A yearly average of the last frost free days, which gives an indication of when it is safe to plant outdoors.
Fruit - In flowering plants, the structure which encloses the seeds. True fruits develop from the ovary wall, such as bananas and tomatoes, though not all fruits are edible, such as the dry pods of milkweed or the winged fruits of the maple.
Fulvic acid - A yellow to yellow-brown humic substance that is soluble in water under all pH conditions. Fulvic acid is a short chain molecule derived from humic acid (long chain), so as a result fulvic acid is more stable in hydroponic solutions.
Fungi - Microorganisms that lack chlorophyll. They differ from bacteria by having genetic material arranged on chromosomes, and a membrane surrounding the nucleus. Fungi includes mushrooms, moulds, yeasts and rusts. Many fungi are used in industry: in brewing, baking, to make antibiotics, vitamins and food proteins.
Fungicide - Chemical used to control fungal diseases. Despite the name, most fungicides only slow down or prevent the spread of disease -- only a few actually kill the fungus.
Fungus gnat - Minute blackish gregarious flies destructive to mushrooms and seedlings.
Fusarium wilt - A plant wilt caused by fungi of the genus Fusarium. Tomato, potato, pepper, eggplant, artichoke, beets, broad beans, turnip, radish, cucumber, muskmelon and watermelon are severely affected. Asparagus, bean, broccoli, brussels sprouts, cabbage, cauliflower, celery, chives, collards, garlic, kale, kohlrabi, leek, lettuce, mustard, onion, parsley, peas, rutabaga, spinach and turnip are sometimes affected. Corn, grain and grass are not hosts.
Fusarium - any of several fungal diseases that afflict plants; commonly called dry rot or wilt.
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