HORT-201-EXAM #2 REED
What is photo-oxidation?
destruction of chlorophyll by high light intensity
What is radiational cooling?
loss of heat by long wavelength infrared radiation
What is Dew Point?
the temperature at which air reaches 100% relative humidity
What is Cardinal Temperature?
the temperature range in which plants grow and survive
What is the specific heat of water?
1
What is a Kilo calorie?
1000 calories
What is the Maximum Cardinal Temperature for survival of plants?
130 degrees Fahrenheit or 54 degrees Celsius for most species of plants
What is the survival temperature for semi-hardy plants?
15-29 degrees Fahrenheit or -9 to -2 Celsius
What is the survival temperature for tender or chilling sensitive plants?
32-45 degrees Fahrenheit or 0-7 degrees Celsius
What is the minimum cardinal temperature for growth?
40-50 degrees Fahrenheit or 5-6 degrees Celsius
What is the Maximum Cardinal Temperature for growth of plants?
90-96 degrees Fahrenheit or 32-36 degrees Celsius for most species of plants
What is vernalization?
A cold treatment (32 - 45 degrees F for 4-12 weeks) required to trigger or initiate flower formation in biennials
What is bud chilling?
A period of cold to satisfy chilling requirement of bulbs to overcome flower bud rest
What is Transpiration?
A plant is greater in high light intensity due to heat buildup, but transpiration may decrease if it gets to bright and then to hot which causes the stomata to close conserving water
What is Heat?
A quantitative measure of the amount of energy which is measured by the quantity or amount of heat
What is Dormancy and what is its purpose?
A state of inactive growth mean to help plants, bulbs or seeds survive adverse conditions
What is Temperature Inversion?
A warm air mass above a cold air mass
What is Growth Substance
All naturally occurring or synthetically produced substances that affect physiology, growth and development of plants
What is a Hormone?
An endogenous or naturally occurring compound that is produced or synthesized in one part of a plant and causes a change in physiology, growth or development in another part of the plant
What is the significance of Latitude in the earths temperature?
Average temperature decreases north and south of the equator due the sun's rays spread over a greater area and the sun's rays pass obliquely through a thicker layer of the atmosphere
The synthetic (man made) versions of Cytokinin are?
Benzyladenine (BA) Pyranylbenzyladenine (PBA)
What are the measures of heat energy?
Calorie Kilocalorie Specific Heat Heat of Fusion Heat of Vaporization
What does Abscisic Acid do?
Causes bud or seed dormancy, leaf abscission or defoliage and the stomata of plants to close a response to drought conditions
What are two types of Cooling Injury?
Chilling Injury: damage or death due to cold above freezing temperatures Freeze Injury: damage or death due to temperatures below freezing or 28 degrees Fahrenheit
What are the three ways to transfer heat?
Conduction Convection radiation
What is the Optimum Temperature for cool season plants?
Cool temperature plants grow best at 65-75 degrees Fahrenheit or 18-24 degrees Celsius In Southern U.S. these grow as fall or winter crops In Northern U.S. these grow as late spring, summer or early fall crops
When is the Winter Solstice?
Dec 21 or 22 when the earth's axis is tilted 23 ½ degrees away from the sun
What does Cytokinin do?
Delays Scenecence or death of leaves, may overcome dormancy or stimulate germination, and assist in adventitious shoot formation
What is light duration?
Determines the total amount of light energy received Total amount of light energy = quantity X # hours of light
How does Freezing Temperature injure plants?
Direct cellular damage caused by Very Rapid temperature drop and ice forms in the cytoplasm and ruptures the cell Moderate Temperature drop ice forms in cell wall and cytoplasm and causes dehydration
What is Etiolation
Elongated, pale green to yellowish growth due to low light intensity. Ex. blades of grass covered for several days
The naturally occurring hormone Ethylene is also known as?
Etephon or Ethrel both release ethylene inside plants. When applied to plants it is in liquid form and becomes a gas once inside plant
What is Dessication?
Excessive drying out due to cold soil and dry winds
What is De-Vernilization?
Exposure (1 day to 1 week) to high temperatures (90-95 degrees F) immediately after vernalization which erases the treatment
What is Conduction?
Flow of heat energy through a medium from one molecule to another
What is Bolting?
Flower formation and seed stalk elongation in bienials
How does high temperature damage plants?
High temperature will cause plants to either die quickly because it denatures proteins in the plant at 130 degrees Fahrenheit or It will die slowly due to Dessiccation (drying out) sun scald or scorch and Respiration exceeds photosynthesis and depletes stored food in plant
Where is Abscisic Acid naturally produced?
In plastids especially chloroplast
Where is Ethylene naturally produced?
In ripening fruits, aging flowers, germinating seeds, and wounded tissue of plants, fruits or vegetables
Where is Gibberellic Acid naturally produced?
In the shoot tips, root tips and embryos
Where is Cytokinin naturally produced?
In the shoot tips, root tips, and embryos of plants
How does Chilling Temperature injure plants?
Increased protein and enzyme breakdown and increased membrane leakiness. Membranes lose selective permeability and often appears deeper green and slightly waterlogged
The naturally occurring hormone Auxin is also known as?
Indoleacetic Acid)
The synthetic (man made) versions of Auxin are?
Indolebutyric Acid (IBA) Naphthaleneacetic Acid (NAA) (BLOSSOM SPRAY) 2,4 Dichlorophenoxyacetic acid ( 2,4 D) : used as a weed killer (herbicide) for broad leaf weeds
What is Apical Dominance?
Is determined by the amount of auxin in the plants high concentrations of auxin will prevent growth at lateral buds and lower concentrations will stimulate growth at lateral buds.
What does Gibberellic Acid (GA) do?
It causes elongation of cells in plants, can cause bolting in biennials, may overcome and substitute for cold treatment, and may increase or speed up seed germination. Also favors staminate flower formation on monoecious plants
What is the heat of vaporization?
It causes the cooling of plants, animals and the environment. This can be accomplished with the use of sprinkler irrigation or swamp coolers
What is the Greenhouse effect?
It gets its name from the heat build-up characteristic in greenhouses during the day. Short wavelength radiation from the sun warms the earth and re-radiated by long wave-length IR back into the atmosphere
Carbon Dioxide emission has caused and increase in what?
It has caused an increase in carbon dioxide emissions from about 300 ppm to 350 ppm which was caused by the burning of fossil fuels and forest and oil fires
What is Infrared Radiation?
It is a form of radiation easily converted to heat energy when absorbed, and vice versa. Ex. Infrared heaters radiational cooling and frost protection with fog, smoke and overhead coverings
What is the sub-tropical mean?
It is often used to describe the southern most area of the Temperate Climatic Zone (ex. South Florida and the Rio Grand Valley) but is not an official climatic zone
What is the heat of fusion?
It is used for low intensity heat production. If you were to freeze a 55 gal drum of water it would give off heat due to heat of fusion. 55 gal X 8 lb/gal X 454 g/lb X 80 cal/g= 16 million calories or 45,000 BTU's of heat released
What is Change Of State?
It is when a constant temperature is maintained when to phases of water are present (ex. solid (ice) liquid (water). And as the ice melts in the glass a constant temperature is maintained until the ice is completely melted
What does Auxin do?
It naturally occurring hormone created in the shoot tips or embryos of plants which triggers elongation of plant cells
What is Specific Heat?
It stabilizes the temperature of plants(plants are 75-95% water) and the temperature of the environment especially around bodies of water.
When is Summer Solstice?
June 21 or 22 when the earth's axis is tilted 23 ½ degrees toward the sun
When doe Earth experience Minimum Average Temperature?
Just before sunrise
What is the survival temperature for hardy plants?
Less than 0 degrees Fahrenheit or -18 degrees Celsius
When is the Vernal Equinox?
March 20 or 21 when the earth's axis is oriented oblique to, but neither towards or away from the sun
When does Earth experience Maximum Average Temperature?
Mid-Afternoon
What is Stratification?
Moist cold storage at 32-45 Degrees F for 6-12 weeks required to overcome embryo rest
What methods are used to decrease high temperatures on plants?
Mulch can be used to insulate the soil from the sun's rays Decrease the light intensity by shading crops a shading compound or net or evaporative cooling by spraying foliage during mid-afternoon using fog, fine mist or a fan and pad cooling system
What is Phototropism?
Plants response to light
What are the two types of Dormancy and How are they achieved?
Quiescence: dormancy imposed by external or environmental conditions Physiological (Rest) : dormancy imposed by internal or physiological conditions
When is the Autumnal or Fall Equinox?
September 22 or 23 when the earth's axis is oriented oblique to, but neither towards or away from, the sun
What is the optimum light intensity for sun and shade plants?
Sun plants 1200 to 2000 ft-c Shade plants 20 to 100 ft-c
What are the effects of Winter Solstice?
Sun's rays spread over a larger area of the earth's surface the rays of the sun pass obliquely through a thicker layer of the atmosphere and the days are shorter
What is Radiational Freeze or Frost?
Temperature drops due to radiational cooling which results in a temperature inversion on calm clear nights
Where does the temperature fluctuate most during Seasonal Variation?
The Temperate Zone
What is Heat of Vaporization?
The amount of heat (calories) needed to change 1 gram of a substance from liquid to gas at its boiling/condensation point
What is the Heat of Fusion?
The amount of heat (calories) needed to raise 1 gram of a substance by 1 degree Celsius
What is a calorie?
The amount of heat (heat energy) required to raise 1 gallon of water by 1 degree Celsius
What is a British thermal unit?
The amount of heat required to raise 1lb of water by 1 degree Fahrenheit
What is the Temperate Climatic Zone?
The area between 23 ½ degrees and 66 ½ degrees latitude North and South between the Tropic of Capricorn and Antarctic Circle and has hot and cold seasons
What is the Tropical Climate Zone?
The area between 23 ½ degrees latitude N and S of the equator located between the Tropic of Cancer and the Tropic of Capricorn this zone is very warm and rarely if ever freezes
Where is the Arctic Climatic Zone located?
The area between 66 ½ degrees North latitude and the North Pole and 66 ½ degrees latitude and the South Pole this area is always frozen
What is Climate?
The average atmospheric conditions over a long period of time
What is Photoperiod?
The day length or length of light a plant receives in 24 hours. Plants measure this period to know seasons and when to flower or bloom
What triggers Physiological Dormancy
The environment such as short days decreasing temperatures low level of growth promoters high level of growth inhibitors
What is Radiation?
The flow of energy as electromagnetic waves, with no transferring medium when radiation is absorbed it may be converted to heat energy
What is the Site of Perception?
The growing point or apex of stems
What is Blanching?
The lack of color due to light exclusion
What is Convection?
The mass movement of heat energy
What is chilling requirement?
The number of hours of cold temperature between 32-45 degrees F required to overcome rest (physiological dormancy)
What is Thigmotropism?
The plants response to touch i.e. the tendrils of a cucumber plant will wrap around a fence when it grows
What is Temperature?
The qualitative measure of the amount of heat energy which is measured by the intensity or degree of heat energy
What is Tropism?
The response of plants to environmental or physical stimuli
What is Geotropism?
The response to gravity all plants will grow vertically regardless of their placement
What are the effects of the Summer Solstice?
The sun's rays are concentrated over a smaller area they travel through a thinner layer of the atmosphere and the days are longer
How does Elevation and Altitude affect temperature?
The temperature will decrease one degree for each 330 ft in altitude
Seasons are caused by what?
The unique tilt of the earth and orientation of the sun
What are the three global climate zones?
Tropical Climate Zone Temperate Climatic Zone Artic Climatic Zone
What plants are sensitive to chilling Injury?
Tropical Plants Tropical Fruits Summer Annuals and bedding plants Chilling sensitive vegetables
What triggers Quiescence?
Unfavorable environmental conditions too dry, cold, hot, etc External factors such as a hard seed coat
What is the Optimum Temperature for warm season plants?
Warm season plants grow best in 78-90 degrees Fahrenheit or 24-32 degrees Celsius In Southern US these plants grow in late spring, summer and early fall In Northern US these plants grow in summer, but for some warm season crops the growing season may be to short to get a good yield
What is Advective Freeze
When the temperature drops below freezing, but remains above the current dew point
What are the two types of Radiational Freezes?
White Frost: occurs when the temperature drops below both the current dew point and below freezing Black Frost: occurs when the temperature drops below freezing, but remains above the current dew point
The naturally occurring hormone Cytokinin is also known as?
Zeatin Kinetin (not found in plants)
Physical or mechanical damage is caused by what?
breaking due the weight of ice on the plant
What is light acclimatization?
conditioning of plants to low light intensity or interior environments
