Term
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Definition
| an endogenous or naturally-occurring compound that is produced or synthesized in one part of the plant and causes a change in physiology, growth or development in another part of the plant; usually present in very small quantities. |
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Definition
| all naturally-occurring or synthetically produced substances that affect the physiology, growth and development of plants. |
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Term
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Definition
Natural Version: indoleacetic acid (IAA)
Synthetic Version: indolebutyric acid (IBA), naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D)
Site of Production: shoot tips, embryos |
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Term
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Definition
Naturally Occurring: zeatin, kinetin (not in plants)
Synthetic Version: benzyladenine (BA),
pyranylbenzyladenine (PBA)
Production Zone: root tips, embryos |
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Term
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Definition
Natural: over 90
Sythetic: none
Production sight:shoot tips, root tips, embryos |
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Definition
Natural: ethylene
Synthetic: ethephon or ethrel
Production sight: ripening fruits, aging flowers, germinating seeds, wounded tissue |
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Term
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Definition
Natural: abscisic acid
Synthetic: none
Production Sight: plastids, especially chloroplasts |
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Term
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Definition
| response to light due to auxin |
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Definition
| response to gravity due to auxin |
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Definition
| response to touch due to auxin |
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Definition
| determined by apical bud, partly due to auxin produced |
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Term
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Definition
-Tropisms: response of plants to environmental or physical stimuli
- Apical dominance
- Fruit set: lox concentrations stimulate
- Fruit or flower thinning: high concentrations cause
- Herbicides: 2,4 D @ high concentrations (only kills dicots)
-Adventitious ROOT formation |
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Term
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Definition
- May delay leaf aging or abscission
- Seed Germination: may overcome dormancy or stimulate germination
- Adventitious shoot formation |
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Term
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Definition
- Lack of can cause rosette or dwarf plants
- May cause bolting in biennials
- increases size in seedless grapes
- Bud Dormancy: may overcome and substitute for cold treatment
- May increase or speed up seed germination
- Sex expression: favors staminate flower formation on monoecious plants |
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Term
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Definition
- Stimulates fruit ripening
- Triggers flowering in some bromeliads (pineapple)
- Causes senescence of cut flowers
- Leaf Abscission (leaf drop)
- Leaf Epinasty (curling and contortion of leaves)
- Sex Expression: favors pistillate flower formation on monoecious plants |
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Definition
- Causes bud or seed dormancy
- Leaf abscission (leaf drop)
- Stomata: causes stomata to close (response to drought stress) |
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Definition
| chemicals that block GA synthesis; are used in greenhouse and bedding plant production to produce compact plants. |
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Definition
- a qualitative measure of the amount of heat energy;
- it is a measure of the intensity or degree of heat energy. |
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Term
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Definition
- a quantitative measure of the amount of heat energy;
- it is a measure of the quantity or amount of heat energy. |
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Definition
| amount of heat (heat energy) required to raised 1 g of water by 1 oC. |
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Term
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Definition
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Term
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Definition
amount of heat (# calories) needed to raise 1 g of a substance by 1oC. (water = 1.0)
practical purposes:
-stabilizes the temperature of plants (plants are 75-95% water)
-stabilizes the temperature of the environment, esp. around large bodies of water |
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Term
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Definition
amount of heat (# calories) needed to change 1 g of a substance from solid to liquid at its melting/freezing point. (water = 80 cal/g)
Practical purposes:
-used for low intensity heat production
-if you freeze a 55 gal drum of water: 55 gal x 8 lb/gal x 454 g/lb x 80 cal/g = 16 million calories or 45,000 BTU released |
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Term
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Definition
amount of heat (# calories) needed to change 1 g of a substance from liquid to gas at its boiling/condensation point. (water = 540 cal/g)
Practical Purposes:
- causes cooling of plants, animals and the environment
- evaporative cooling system, or fan-and-pad cooling system
- sprinkler irrigate greenhouse or nursery crops in mid afternoon |
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Term
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Definition
| flow of heat energy through a medium from molecule to molecule. |
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Term
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Definition
| mass movement of heat energy |
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Definition
| flow of energy as electromagnetic waves, with no transferring medium; when radiation is absorbed it may be converted to heat energy. |
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Term
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Definition
| -the glass bounces the long wavelength IR back down. This trapped long wavelength IR is absorbed by objects, which causes further heating, and the cycle continues. |
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Term
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Definition
Practical Applications:
- a form of radiation easily converted to heat energy when absorbed and vice versa
- infrared heaters
- radiational cooling
- frost protection with fog, smoke and overhead coverings |
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Term
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Definition
Practical Application:
- constant temperature when two phases of water are present
- frost protection with overhead irrigation
- pressure cooking |
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Term
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Definition
| the average atmospheric conditions over a long period of time. |
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Definition
| the current and temporary atmospheric conditions. |
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Term
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Definition
| the climate or weather conditions of a relatively large area, usually 24-50 miles. |
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Term
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Definition
| the climate or weather conditions of a smaller localized area; ex. a valley, stand of trees, open field, sides of a hill, etc. |
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Term
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Definition
| the climate or weather conditions of a very small area, ex. inside vs. outside, a canopy, upper vs. lower leaf surface, etc. |
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Term
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Definition
-The area between the 23 1/2o latitude N and S of equator.
-Between the Tropic of Cancer (off S. tip of Fla. and middle of Mexico) & Tropic of Capricorn
-Warm, rarely if ever freezes |
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Term
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Definition
-The area between the 23 1/2o & 66 1/2o latitude N & S.
-Between Tropic of Cancer and Arctic Circle, and Tropic of Capricorn and Antarctic Circle.
-Has hot and cold seasons
- Temperature fluctuates the most |
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Term
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Definition
| -often used to describe the southern most area of Temperate Climatic Zone (ex. South Florida and Rio Grande Valley), but it is not an official climatic zone. |
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Term
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Definition
-The area between the 66 1/2o N latitude and the N. Pole and the 66 1/2o S latitude & the S. Pole.
-North of Arctic Circle, and south of Antarctic circle.
-Always cold and frozen |
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Term
| Effects of Latitude on Temperature |
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Definition
-average temperature decreases north and south from equator
Due to:
a) sun's rays spread over greater area
b) sun's rays pass obliquely through thicker layer of atmosphere |
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Term
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Definition
| June 21 or 22, when earth's axis is tilted 23 1/2o towards sun |
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Term
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Definition
-Caused by the unique tilt of earth and orientation to sun
Warmer due to:
a) sun's rays concentrated over smaller area
b) sun's rays travel through thinner layer of atmosphere
c) days longer
Colder due to:
a) sun's rays spread over larger area
b) sun's rays pass obliquely through thicker layer of atmosphere
c) shorter days |
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Term
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Definition
| Dec. 21 or 22, when earth's axis is tilted 23 1/2o away from sun |
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Term
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Definition
| March 20 or 21, when earth's axis is oriented oblique to, but neither towards nor away from, the sun |
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Term
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Definition
| Sept. 22 or 23, when earth's axis is oriented oblique to, but neither towards nor away from, the sun |
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Term
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Definition
| a) minimum average temperature: just before sunrise b)maximum average temperature: mid-afternoon |
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Term
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Definition
a)small scale - hot air rises, cold air sinks into low areas
b) large scale - the temperature decreases 0.6oC/100 m or 1 oF/330 ft increase in altitude |
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Term
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Definition
| warmest to coldest slopes of a hill sides of a building, etc.: south > west > east > north |
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Term
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Definition
| stabilizes temperature; warmer in winter, cooler in summer |
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Term
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Definition
a) dark soils warm faster than light soils in spring
b) dry soils warm faster than moist soils in spring |
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Term
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Definition
| the temperature range in which plants grow and survive. |
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Term
| Minimum Cardinal Temperature |
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Definition
a) growth: 40-50F (5-6 C) for most species
b)survival
1)tender or chilling sensitive: 32 to 45 oF (0 to 7 oC)
2) semi-hardy plants: 15 to 29 oF (-9 to -2 oC)
3) hardy plants: less than 0 oF (-18 oC) |
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Term
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Definition
grow best at 65-75 oF (18-24 oC)
1) in southern U.S.: grow as fall-winter crops.
2) in northern U.S.: grow in late spring, summer, early fall |
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Term
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Definition
grow best at 78-90 oF (24-32 oC)
1) in southern U.S.: grow in late spring and summer, early fall
2) in northern U.S.: grow in summer, but for some warm season crops the growing season may be too short to get good yield. |
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Term
| Maximum cardinal temperature |
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Definition
a) growth: 90-96 oF (32-36 oC), most species
b) survival: 130 oF (54 oC), most species. |
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Term
| Effects of High temperature |
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Definition
A) Dies quickly
1) Denatures proteins (unfolding of proteins) - at 130 oF
B) Dies slowly or just poor growth
1)Desiccation - causes excessive drying-out
2)Sun scald or scorch - desiccation followed by death of tissue
3)Respiration exceeds photosynthesis- depletes stored food |
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Term
| Methods to decrease high temperature |
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Definition
A) Soil temperatures
1)mulch - insulates and blocks out light
B) Air temperatures
1)Decrease light intensity (decrease both visible and infrared if possible)
a) lath covering over nursery drops
b) shade cloth or saran over nursery crops or greenhouses
c) shading compound or white wash painted on greenhouse roof
d) colored solution flowing through a double-layered greenhouse roof (primarily decreases IR)
2)Evaporative cooling (relies on heat of vaporization)
a) spray foliage and physical structures during mid-afternoon
b) fine mist or fog injected into a greenhouse
c) fan-and-pad cooling system in a greenhouse |
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Term
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Definition
| damage or death due to cold, yet above freezing temperatures (32 to 45 oF). |
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Term
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Definition
| damage or death due to temperatures below freezing (below about 28 oF). |
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Term
| Radiational freeze or frost |
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Definition
| temperature drops due to radiational cooling which results in a temperature inversion; occurs on calm, clear nights |
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Term
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Definition
| loss of heat by long wavelength infrared (IR) radiation. |
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Term
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Definition
| a warm air mass above a cold air mass. |
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Term
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Definition
| the temperature at which air reaches 100% relative humidity. |
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Term
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Definition
| occurs when the temperature drops below both the current dew point (dew forms) and below freezing (dew freezes). |
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Term
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Definition
| occurs when the temperature drops below freezing, but remains above the current dew point. |
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Term
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Definition
| temperature drops due to the invasion of a cold air mass or convection current. |
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Term
| Effects of Chilling Temperatures |
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Definition
1) Increased protein and enzyme breakdown.
2) Increased membrane leakiness
a) membranes lose selective permeability
b) often appears deeper green and slightly waterlogged
Sensitive Plants:
● tropical plants
● tropical fruits
● summer annuals and bedding plants
● chilling sensitive vegetables |
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Term
| Effects of Freeze Temperatures |
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Definition
1) Direct cellular damage - damage to individual cells.
a)Very rapid temperature drop
- ice forms in cytoplasm and ruptures cell
- seldom occurs, but always fatal
b)Moderate temperature drop
- ice forms in cell wall and cytoplasm dehydrates
- most commonly occurs, not fatal to hardy or cold acclimated plants.
more sensitive vs. more resistant:
young tissue vs. old mature tissue
growing tissue vs. dormant tissue
flower buds vs. vegetative buds
roots vs. shoots |
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Term
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Definition
| excessive drying-out due to cold soil and dry winds. |
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Term
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Definition
| soil freezes and expands, thus heaving the plant out of the soil |
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Term
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Definition
| cambium under bark freezes, expands, then splits the bark. |
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Term
| physical or mechanical breakage (ice damage) |
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Definition
| from weight of ice on plant |
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Term
| Sun scald or Southwest injury |
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Definition
| excessive desiccation on southwest side of tree; sunlight is brightest on the south and west side. |
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Term
| Prevention of Radiational freeze or frost |
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Definition
1) Decrease rate of radiational cooling
a) hot caps or plastic tents
b) mulches
c) foams
d) fog or water vapor
e) smoke
2) Increase air temperature
a) eliminate temperature inversion:
1) wind machines
2) helicopters
b) irrigation
1) flood irrigation; water is warmer and stabilizes temperature (due to high specific heat)
2) overhead irrigation; constant temperature at 32 oF when liquid/ice present
c)oil burners or smudge pots |
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Term
| Prevention of Advective Freeze damage |
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Definition
1) Plant selection - the ideal method, because then no other method is needed
2) Radiational freeze methods - some are moderately effective for mild, short freezes.
a) Insulate: mulch, foam, hot caps (NOT fog or smoke)
b) Increase air temperature: irrigation, oil burners or smudge pots if mild and little wind
c) CANNOT USE: fog, smoke or eliminate temperature inversion
3) Site selection - avoid north side of hills, buildings, etc.; avoid low areas, valleys, etc.
4) Delay development in spring - avoids damage to new spring growth and flower buds from late spring frost.
5) Harden-off or cold acclimation in fall: is a normal part of dormancy and preparation of the plant for for winter.
Naturally triggered by:
a) short days
b) cool temperatures
c) cold temperatures |
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Term
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Definition
| state of inactive growth to survive adverse conditions |
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Term
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Definition
dormancy imposed by external or environmental conditions
-What triggers?
a) Unfavorable environmental conditions
b) External factor, such as hard seed coat
-What causes?
Unfavorable environment; too dry, cold, hot, etc.
-How to overcome?
Remove unfavorable environment |
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Term
| Rest or Physiological Dormancy |
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Definition
dormancy imposed by internal or physiological conditions; common among temperate perennial plants
-What triggers?
Environment:
a) short days (SD)
b) decreasing temperatures
-What causes?
Internal physiology is unfavorable:
a) low level of growth promoters (e.g. auxin or gibberellic acid), and/or
b) high level of growth inhibitors (e.g. ABA)
-How to overcome?
Give period of cold between 32-45 oF (0-7 oC), which satisfies the chilling requirement.
-chilling requirement - the number of hours of cold between 32-45 oF (0-7 oC) required to satisfy rest |
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Term
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Definition
| shorter chilling requirement |
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Term
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Definition
| longer chilling requirement |
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Term
| cold storage or bulb chilling |
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Definition
a period of cold to satisfy chilling requirement of bulbs to
overcome flower bud rest (physiological dormancy).
❍usually 6-12 weeks at 35-45 oC (0-7 oC) in a cooler or refrigerator. |
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Term
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Definition
plants that have a 2 year life cycle
LIFE CYCLE
1st year - grow vegetatively as rosettes or bulbs in late summer-fall
winter - are vernalized by cold of winter to trigger flower inception
2nd year - in spring flower forms and develops, called bolting
GROWTH HABITS
rosettes - radish, carrot, turnip, mustard, kale, bluebonnet, Indian paint brush
heads - cabbage
bulbs - onion |
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Term
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Definition
| a cold treatment (32-45 oF for 4-12 weeks) required to trigger or initiate flower formation in biennials. |
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Term
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Definition
| flower formation and seed stalk elongation in biennials. |
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Term
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Definition
| exposure (1 day to 1 week) to high temperatures (90-95 oF) immediately after vernalization, which erases the vernalization treatment. |
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Term
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Definition
| growing point (apex) of stems. |
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Term
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Definition
| visible radiant energy in the 400 to 700 nm wavelength region of the spectrum. In other words,it is the form of radiant energy (i.e. radiation) that animals can see. It is also the wavelengths of radiant energy that plants use in photosynthesis and for most other reactions that require light. |
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Term
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Definition
| heat energy is converted to radiant energy as long wavelengths in the infrared (IR) region of the spectrum. |
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Term
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Definition
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Term
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Definition
1 lumen per square meter
1 foot-candle = 10.76 lux |
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Term
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Definition
| - thicker, due to thicker palisade parenchyma layer |
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Term
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Definition
- thinner, due to thinner palisade parenchyma layer
- therefore, higher proportion of spongy mesophyll
- larger size
- softer and more pliable |
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Term
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Definition
| destruction of chlorophyll by high light intensity. |
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Term
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Definition
| elongated, pale green to yellowish growth due to low light intensity. |
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Term
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Definition
| lack of color development due to exclusion of light |
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Term
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Definition
| conditioning of plants to low light intensity interior environments. |
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Term
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Definition
| absorbs red (660 nm) and far red (730 nm) light; involved in photomorphogenic and photoperiodic responses |
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Definition
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Term
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Definition
| absorbed by carbon dioxide and water vapor |
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Term
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Definition
| plants that exhibit their photoperiodic response when the photoperiod is shorter than a critical photoperiod. |
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Term
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Definition
| plants that exhibit their photoperiodic response when the photoperiod is longer than a critical photoperiod. |
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Term
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Definition
| reflected sky light that occurs approximately 1/2 hour before sunrise and 1/2 hour after sunset. |
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Term
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Definition
| the day length a plant perceives, which will be the absolute day length (time from sunrise to sunset) plus 1 hour of civil twilight. |
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Term
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Definition
-the photoperiod (absolute day length + civil twilight) above or below which the photoperiodic response is turned-on or turned-off.
-each species has its own unique critical photoperiod that it "looks" for. |
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