| Ebb
and Flow: |
type of hydroponics technique also known as flood and drain. |
| Electrode: |
a
conductor through which electricity enters or leaves something. |
| Elongate: |
grow
in length, make or become larger. |
| Embolism: |
blockage
in the vessels such as an air bubble. |
| Emit: |
to
give off, discharge or send out light. |
| Endodermis: |
a
one cell layer of tissue outside the vascular areas and
is particularly important in roots where endodermal cells
are thickened with casparian strips for control of water
transport. Water and salts have to pass through the endodermal
cells which act as a kind of valve. |
| Entropy: |
the
amount of disorder or degree of randomness of a system. |
| Enzyme: |
A protein molecule that catalyses a biochemical reaction
by lowering the activation energy required for the reaction
to proceed. |
| Epidermal
Cells: |
in
stems and leaves, these cells secrete a cuticle. |
| Epidermis: |
in
plants, this is the thin tissue, usually one cell thick,
that surrounds young roots, stems and leaves. |
| Esoteric:
|
intended for or understood by only a small number of people
with a specialised knowledge. |
| Exponentially:
|
an
increase that becomes more and more rapid. |
| F1: |
first
generation of filial offspring of a particular cross. |
| F2 |
second generation, or grandchildren of a particular cross. |
| F3: |
third
generation, or great grandchildren of a particular cross. |
| F4: |
fourth generation, or great great-grandchildren of a particular
cross. |
| Female:
|
having
pistils or ovules and seed-producing. |
| Fertiliser
burn: |
over fertilisation; leaf tips burn and curl. |
| Flood
and drain: |
type
of hydroponics technique also known as ebb and flow. |
| Flushing: |
clean
by passing large quantities of water through. |
| Foliar
feeding: |
a
method of supplying plants with nutrients by spraying an
aqueous solution onto the leaves. |
| Fumigation: |
disinfect
with the fumes or smoke of certain chemicals. |
| Fungicide: |
any
substance that kills fungi. |
| Gene: |
fundamental
physical unit of heredity that transmits information from
one cell to another and therefore from one generation to
another. |
| Genetic:
|
of
or relating to genes. |
| Genome: |
the
complete complement of genetic material in a cell or carried
by an individual. |
| Genus:
|
a
taxon immediately above that of a species and containing
usually a group of closely related species. |
| Germination: |
the
beginning of the growth of a seed, spore or other structure
that is dormant. |
| Gypsum: |
a
mineral. |
| Herbicide: |
any
chemical that kills plants. |
| Hermaphrodite: |
any
plant having both male and female flowers. |
| Hertz
(Hz): |
a
unit of a frequency measuring cycles per second. |
| HID: |
High
Intensity Discharge. |
| Honeydew: |
the sugary waste substance passed out by aphids, scales
and mealybugs and secreted onto foliage. |
| Hood: |
reflective cover of a HID lamp. |
| Hormone: |
a
chemical that is produced in the plant and controls growth
and development. Root hormones promote the rooting of cuttings. |
| Horticulture: |
the science and art of growing plants. |
| Humidity
(relative): |
the comparative amount or moisture in the air and the largest
amount of moisture the air could contain at the same temperature. |
| Humus: |
organic
material that is derived from the breakdown of plant and
animal material occurring in the surface layers of the soil.
Humus is black in colour, very fertile and a soil improver. |
| Hybrid: |
an
offspring of a cross between two genetically different individuals.
|
| Hybridisation:
|
artificial
creation or breeding of two different species or varieties
to produce hybrids. |
| Hydroponics: |
the
science of growing plants without soil, in which the roots
are suspended in aerated water containing known quantities
of chemicals that can be adjusted to suit changing conditions. |
| Hydroponicum: |
hydroponic
installation. |
| Hygrometer: |
instrument
for measuring relative humidity. |
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