Abscission: The dropping of leaves, flowers, or fruit by a plant. This can result from natural growth processes (e.g., fruit ripening) or from external factors such as temperature or chemicals.
Abscission Layer: Specialized cells, usually at the base of a leaf stalk or fruit stem, that trigger both the separation of the leaf or fruit and the development of scar tissue to protect the plant.
Absorption: The intake of water and other materials through root or leaf cells.
Adventitious: Growth not ordinarily expected, usually the result of stress or injury. A plant’s normal growth comes from meristematic tissue, but adventitious growth comes from nonmeristematic tissue.
After-ripening: The seed maturation process that must be completed before germination can occur.
Algae: is an informal term for a large, diverse group of photosynthetic organisms which are not necessarily closely related and are thus polyphyletic
Algal Bloom: A rapid growth of microscopic algae or cyanobacteria in water, often resulting in a colored scum on the surface.
Allelopathic: An allelopathic plant is one that secretes and/or broadcasts chemical compounds that are actively inhibitive to the growth of plants around it. Look under any redwood tree: you will find very little weed growth among the redwood needles because they are allelopathic. An example in aquaponics systems is tomatoes. If any other plant’s roots are touching or nearby a tomato’s roots (except basil, which doesn’t seem to mind), the other plant will do poorly and perhaps even die from the contact.
Apex: The tip of a stem or root.
Apical bud: A bud at the tip of a stem.
Apical dominance: The inhibition of lateral bud growth by the presence of the hormone auxin in a plant’s terminal bud. Removing the growing tip removes auxin and promotes lateral bud break and subsequent branching, usually directly below the cut.
Apical meristem: A region of actively dividing cells at the tip of a growing stem or root.
Attenuate: When a plant grows tall and spindly instead of “bushing out” as it normally would; this is an indication the plant is not getting enough light, and/or is planted too densely.
Autotrophic nutrition: A form of nutrition in which complex food molecules are produced by photosynthesis from carbon dioxide, water, and minerals
Buffering action: The ability of a nutrient solution or raw water to resist changes in pH
Chlorosis: An abnormal yellowing of a leaf.
Clay: The smallest type of soil particle (less than 0.002 mm in diameter).
Cole Crops: A group of vegetables belonging to the cabbage family; plants of the genus Brassica, including cauliflower, broccoli, cabbage, turnips, and brussels sprouts.
Electrical Conductivity (EC): A measure of the ability of a nutrient solution to conduct electricity, which is dependent upon the ion concentration and nature of the elements present. Visit our selection of solution testing equipment.
Green Leaf Vegetables: Chinese cabbage, lettuce, basil, spinach, chives, herbs and watercress
Fruiting Plants: Cucumbers, tomatoes, capsicum, red onions, string beans, peas, melons, squash
Tuberous Root Plants: ginger, turmeric, ginseng, radishes, carrots, potatoes, turnips, beets, and yams
Growing Medium: Materials that are sometimes used in hydroponic growing to support the plant’s roots and, sometimes, to hold nutrient.
Hardening Off: The process or gradually exposing seedlings started indoors to outdoor conditions before transplanting.
Necrosis: Tissue death, browning of leaf tissue due to a nutritional disorder.
N-P-K: The acronym for the three primary nutrients contained in manure, compost, and fertilizers. The N stands for nitrogen, the P stands for phosphorus, and the K stands for potassium. On a fertilizer label, the N-P-K numbers refer to the percentage of the primary nutrients (by weight) in the fertilizer. For example, a 5-10-5 fertilizer contains 5% nitrogen, 10% phosphorous, and 5% potassium.
Seed Coat: A hard outer covering that protects a seed from disease and insects. Also prevents water from entering the seed and initiating germination before the proper time.
Seedling: A young plant, shortly after germination.
Senescence: (1) The aging process. (2) A descriptive term for a plant that is in the process of going dormant for the season, although technically only the parts that are dying (the leaves) are becoming senescent.
Thermoperiod: The change in temperature from day to night.