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90 Cards in this Set

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What controls the site productivity?What is the major factor influencing plant growth and distribution?
the amount of available water;
Which slopes get more direct solar radiation, what type of soil do they have and what type of trees grow on them usually?
south, southwest, dryer and warmer, pines usually only grow, very little production here
What does water have an influence on?
cell division and stem elongation
What is the largest component of plants, how much of it makes up growing tissue and how much of it makes up woody plants?
water, 80-90%, 45-60%
What does water serve as?
a solvent which transports minerals and dissolved carbohydrates throughout the plant
What are some of the functions of water?
used for turgidity, dissolves a great many chemical substances, reactant in chemical reactions, serves in photosynthesis for source of electrons
What is turgidity?
serves for pressure in plants, necessary for cell enlargement, growth and even maintenance of form in some plants
What is water potential?
movement of water from cell to cell in plants, measure of free energy of water
What is the conversion of a megapascal?
10 bars
What makes up water potential?
turgor potential and osmotic potential
What is osmotic potential due to?
dissolved solutes in the water,(sugar and salt), the more dissolved solutes the lower the osmotic potential
When you see wilted leaves, whats wrong with the water potential?
the turgor potential is at zero
What happened to the water potential when there is dead xylem in trees?
negative turgor pressure, "under tension"
What are auxins?
play major role in cell elongation and tropisms
What is development?
Differentiation of cells into the various tissues and organs.
What is growth?
Refers to an increase in size by cell division and enlargement.
What is osmotic adjustment?
An acclimation where the plant lowers its osmotic potential in response to a drought and in this way maintains turgor despite lower water potential.
What is dessication tolerators?
The ability of plants to still dessicate but still survive
What is dessication postponement?
Decrease water loss, or increase water uptake,
What are drought tolerators?
Have portions during their active life cycle during periods which drought can be expected.
What are drought avoiders?
Plants that complete their entire life cycles before a drought occurs
Ex. Desert species
What are four mechanisms for a drought?
Drought tolerator, avoider, dessication postponement and tolerator
What is acclimation?
A modification of a characteristic in response to the environment
What is adaptation?
Characteristics which are heritable or passed on from generation to generation.
What are two drought mechanisms?
Adaptation and acclimation
What is a drought?
A meteorological event which can be defined as a period without rainfall of sufficient duration that plant growth is impacted negatively.
What is a tensiometer?
Used to measure the water potential of soil
What is the pressure chamber used for?
To measure the water potential in the xylem of woody plants.
What are auxins?
play major role in cell elongation and tropisms
What is development?
Differentiation of cells into the various tissues and organs.
What is growth?
Refers to an increase in size by cell division and enlargement.
What is osmotic adjustment?
An acclimation where the plant lowers its osmotic potential in response to a drought and in this way maintains turgor despite lower water potential.
What is dessication tolerators?
The ability of plants to still dessicate but still survive
What is dessication postponement?
Decrease water loss, or increase water uptake,
What are drought tolerators?
Have portions during their active life cycle during periods which drought can be expected.
What are drought avoiders?
Plants that complete their entire life cycles before a drought occurs
Ex. Desert species
What are four mechanisms for a drought?
Drought tolerator, avoider, dessication postponement and tolerator
What is acclimation?
A modification of a characteristic in response to the environment
What is adaptation?
Characteristics which are heritable or passed on from generation to generation.
What are two drought mechanisms?
Adaptation and acclimation
What is a drought?
A meteorological event which can be defined as a period without rainfall of sufficient duration that plant growth is impacted negatively.
What is a tensiometer?
Used to measure the water potential of soil
What is the pressure chamber used for?
To measure the water potential in the xylem of woody plants.
Which has more water potential; pure water or a solution?
Pure water
In which direction does water move?
High to low regions of water potential
What are selectively permeable membranes?
All the free movement of water to pass through, but not solutes to pass through the membrane of cells
What makes it so that the turgor pressure doesn’t cause the cell’s membrane to rupture?
Rigid cell walls
What is the cohesion-tension theory?
The way that water gets up to the top of trees; the act of the water being “pulled up” by the act of transpiration (evaporation).
What are auxins?
Produced in growing tips, signal response responsible for curvature.
What are tropisms?
Movement in plants in response to unidirectional signals
What do auxins play a role in?
Apical dominance-the tip inhibits the growth of lateral buds
What does auxin do to dormant buds?
Keeps the buds from sprouting
What happens to stems when they are exposed to a lot of light?
The auxin breaks down, allowing dormant buds to sproud into epicormic sprouts.
What is phototropism? How is auxin involved?
Bending towards the light, auxin is on the shaded side causing more curvature towards the light
What is gravitropism?
Movement in response to gravity
What happens to roots when the shoot is dipped in auxin?
They grow more quickly
What is parthenocarpic fruit?
Seedless fruit;growth without fertilization; b/c of auxin
What are gibberellins?
Large group of chemical compounds, stem elongation
Longer days; elongation of plants (bolt)
Flower formation and fruit development
What are “anit-gibberellins used for?
Power lines-instead of so many top clippings, and for greenhouse growth purposes
What are cytokinins?
produced in meristematic regions, called zeatin, cell division and cell and organ enlargement, promote lateral bud development
What are cytokinins used for?
on the fascicular buds of christmas trees, to promote growth
What type of trees are cytokinins applied to?
christmas trees, and fraser firs
What is etylene?
gas produced by ripening fruit, also produced in combustion reactions, causes abscission, causes fruit ripening
What is abscission?
shedding of a plant part, occurs in plants once auxin levels decrease later in the growing season, cells slowly break down creating a line where the shedding occurs
What is abscisic acid?
seed dormancy, induce a resting bud, inhibits seed germination and furthers dormancy, signal of stomata closure,
Which growth regulator causes the witches broom?
cytokinin
Which growth regulator is directly related to broadleaf weed killer?
auxin
Which growth regulator is related to seedling vigor during storage?
ethylene
Which growth regulator is related to stem/internode elongation?
gibberellin
Which growth regulator is related to stomatal closure?
ABA
Which growth regulator is related to rotting fruit?
ethylene
Which growth regulator is related to the crazy rice disease?
gibberellin
Which growth regulator is related to cell division?
cytokinin
What is a condition in which helps temperate woody trees survive harsh winter periods?
dormancy
When are trees generally in cold hardy?
when they are deep in dormancy
What is dormancy in shoots?
period of ceased growth and a resting bud that is enclosed in scales.
When will true dormancy be broken?
when adequate chilling has occured
What is quiescence?
a resting state in response to adverse environmental conditions
What are the stages of dormancy and describe each?
pre-dormancy-reversible of favorable growing conditions take place
true dormancy- non-reversible- only if there is a period of sustained chilling will it break
post-dormancy-bud is still capable of growing but supressed by adverse environmental conditions
What is the main environmental signal that triggers the onset of dormancy?
short Daylength, long nights short days
What happens when daylength changes?
growth regulators are produced, abscisic acid-builds up during fall
When are the best environmental conditions for a plant to enter true dormancy?
cool temperatures and short days
How does water and nutrition effect dormancy?
if the plant is water stressed then it will promote dormancy, if there is high nutrition it will delay dormancy
What conditions help a plant enter post-dormancy?
between the degrees of 2-4 degrees celcius, and with chilling
What does chilling do to ABA?
breaks it down
What is a way that dormant trees survive freezing temps?
cold hardiness
What are frost cracks?
when the pressure from the expanding ice exceeds the strength of the wood
What do temperate trees do to prevent freezing in living tissues as part of the mechanisms of cold hardiness?
deep supercooling, intracellular dehydration
What is deep supercooling?
maintaining water in cells in a liquid state below 0 degrees but above nucleation state
What is intracellular dehydration?
plants can survive at temps. below 40 degrees celsius, but the extracellular spaces are the only liquids that will freeze b/c the liquid is pulled out of the cells, just causing damage from dehydration