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AGRC 111 > plant stress > Flashcards

plant stress Flashcards

1
Q

what is plant stress

A

prevents plants from growing to their full potential

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2
Q

how do plants respond to stress

A

plant stress responses describe characteristics observed when plants detect stress, not all plants respond to stress in the same way.

understanding the plant’s stress is an important and challenging topic

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3
Q

what is abiotic stress caused by

A

It caused by non-living factors

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4
Q

what are some examples of abiotic stress

A

nutrient stress, salt stress, cold stress, heat stress

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5
Q

how does salt cause plant stress

A

salts in soil deprive plants of water and dissolved nutrients.

plant roots have a low water conc. which attracts water into the plant (osmosis)

desolved salts increase osmotic pressure of soil solution less water from the soil will enter roots

if soil solution becomes to conc. the plants die even though there’s an adequate amount of water and dissolved nutrients

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6
Q

how does low-temperature cause plant stress

A

low temp results in slow plant growth and development

when temp goes below 0*C freezing damage can occur

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7
Q

what happens when freezing damage occurs

A

the water within the cell will form crystals and when the temp rises and ice melts the cell contents leak out killing the cell

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8
Q

what are the characteristics of a frost-damaged plant

A

they will appear dark green and water-soaked at first, later becoming blackened and necrotic. in dry conditions, the tissue may appear white as the water from the broken cell evaporates

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9
Q

how do perennials survive the low temperatures

A

perennial species will undergo change to become dormant for the winter. how ever perennials can still be damaged by low temperatures

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10
Q

what species is winter burn noticeable in

A

it is noticeable in ever grees

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11
Q

what is winter burn

A

it is an injury that occurs when the absorption of water by the roots can’t keep up with the amount of moisture lost by the transportation

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12
Q

what conditions does winter burn occur in

A

it occurs mostly on sunny days especially when it is windy and when the soil water is frozen and the plant cat absorb it, or is water is short in supply

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13
Q

what does winter burn look like

A

the injury appears as brown leaf margins or needle tips at the onset of the first period of warm water

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14
Q

what happens if the temperature becomes too high for the plant

A

the cell proteins coagulate (cook) and the plant cell dies

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15
Q

how is wilting caused

A

during warm weather, if plants are unable to take up moisture they will wilt and die because the net assimilation rate is negative (photosynthetic gains are less then respiration losses)

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16
Q

how do plants cope with wilting

A

to cope with the loss of moisture the stomata will close. this results in the plants not being able to perform photosynthesis

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17
Q

what is the stomata

A

they are openings in plants that allow for the movement of gases. vaporized water leaves through the stomata and CO2 enters.

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18
Q

when is the stomata (of most plants) open

A

they are open during the day and closed at night

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19
Q

what is the function of guard cells

A

it’s the cell that surrounds the stomata and opens and closes them

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20
Q

where are the guard cells located

A

they are present in pairs in the outer skin of a plant most are on the underside of the leaf. but can also be present in stems, petals, etc… but NOT the roots

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21
Q

how does turgor pressure work

A

guard cells respond to turgor pressure (water pressure) to regulate the opening. this helps regulate the water.

ex. if the plant is wilted, water pressure is low and the guard cells will then be closed. this is beneficial because the plant won’t lose the little water it has

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22
Q

what is the cuticle of the leaf structure

A

it’s the outer surface of the leaf. there may be a waxy cuticle to reduce moisture loss. the thickness varies among plants and can be affected by the environment

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23
Q

how does temperature affect the cuticle thickness

A

the hotter it is the thicker it is

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24
Q

what is the term for a singular first stomata

A

stoma

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25
Q

what are trichomes

A

they are the hairs on the leaf and they can be both unicellular or multicellular

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26
Q

what is the function of the trichomes

A

they reduce water loss by evaporation by trapping water vapor and increasing humidity by limiting the air movement around the leaf

reflect solar radiation to keep plants cool

some are glandular and release compounds that prevent herbivory

some species have modified trichomes to secrete salt this allows the plant to survive in saline conditions

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27
Q

what is biotic stress

A

stress to a plant caused by another living organism

28
Q

what is a weed

A

any plant that is growing in a place it’s not wanted. this most commonly includes weedy species (plants with no use to humans), volunteer crops, and ornamentals that have escaped

29
Q

why are weeds a problem in an agriculture system

A

compete for light, water, and nutrients
contaminate crop
cause quality downgrading
can kill you or your animals

30
Q

how can weeds contribute to yield loss

A

due to competing for the essentials of plant growth: water, sun, nutrients

31
Q

what is a way weed can prevent herbivores from eating them

A

barbs will prevent this

32
Q

how do weeds contaminate seeds

A

when seeds are inseperateable from the crop seed they lower the grade and value of the grain. exwild mustard seed is so similar to canola its impossible to separate by conventional methods

33
Q

how do weeds contribute to harvest losses

A

this may occur if the weeds are so thick that harvesting is difficult. making for a slower operation and cost of control

34
Q

what is earth tag

A

an example of how weeds contribute to harvest losses. it’s exasperated by green weeds and reduces the quality. (basically, the dirt stick to your seeds)

35
Q

what is an example of toxic weeds

A

rhubarb, death camas, and water hemlock

36
Q

What habits make weeds a problem

A

because they are hard to control as they are very suited to their environment:

  • vigrous growth habits, competitive
  • adapt to a wide range of environments
  • quick life cycle and produce lots of seeds
  • special dispersal mechanism
  • effective dormancy mechanisms
37
Q

what are specialized stems in weeds

A

these structures are often involved in vegetative reproduction. they allow weeds to be very persistent. they can also be a good food source for humans

38
Q

what are rhizomes

A

it a horizontal specialized weed stem that is underground. it serves as an overwintering organ and method of propagation. these stems produce shoots and roots at nodes that grow into a new plant. while establishing itself it gets nutrients from the parent plant

39
Q

what are some adaptations for weed seed distribution

A

wind, water, animals

40
Q

how do weeds get animals to carry seeds

A

by having barbs that stick to the animal

41
Q

how do weeds have adaptations for the wind to carry the seed

A

by having parachutes, wings, or designed for the whole plant to move with the wind

42
Q

what is an infectious plant disease

A

another biotic stress is plant doses that is spread from plant to plant and caused by a living agent (pathogen) they are usually extremely infectious and difficult to control

43
Q

what are the three stages plant disease is broken into

A

inoculation, incubation, infection

44
Q

what is the inoculation stage of a plant disease cycle

A

the period when the pathogen is transferred from a source to a host plant

45
Q

what is the incubation stage of the plant disease cycle

A

the time period from when the pathogen reaches the plant until it begins to affect the plant’s function

46
Q

what is the infection stage of the plant disease cycle

A

multiplication of the pathogen and the appearance of the characteristics of the disease

47
Q

for plant disease when are control methods most effective

A

when implemented during inoculation

48
Q

what is the best disease management

A

to prevent or limit disease. if diseases are already present it may be difficult or not economically viable to control

49
Q

what is the causes for infectious disease

A

they are caused by microorganisms that attack susceptible plants

50
Q

what are environmental or agronomic conditions that can favor disease

A

wet weather

injured or stressed plants

51
Q

what are some ways plants can be injured or stressed making them more susceptible to disease

A

herbicide injury, lack of nutrients, hail damage, deep seedling, poor quality seed

52
Q

what is the most common plant disease-causing organism in western Canada

A

fungi

53
Q

why is fungi the most common plant diseasing plant in Canada

A

because it reproduces by spores. spores can be spread by wind, water, machinery, animals, insects, contaminated seeds, etc.

when moisture is present spores on the plant tissue germanate and grow along the plant surface, and penetrate the plant through the stomata of a plant wound

spores can survive in plant residue in the soil or form overwintering bodies

54
Q

how do plants react to disease

A

disease will cause yield and quality loss

55
Q

what are some symptoms of disease in plants

A
  • death of part or all of the plant
  • lesions on stem will cause a loss of photosynthetic area
  • changes in coloration
  • reduced growth, stunting, dwarfing, wilting
  • galls, tumors
56
Q

what is the best way to identify a plant disease

A

sometimes you can identify by symptoms but often a lab culture will have to be done

57
Q

what are the two groups we make for insects when it comes to insect-plant relationships

A

beneficial and harmful

58
Q

what are beneficial insects

A

perform duties advantageous to humans
ex. pollination incests, parasitic insects (wasps lay eggs in aphids and that kills them when they hatch), flies recycle nutrients

59
Q

what do harmful insects to crops

A

insects that do damage to crops, food, buildings, etc

60
Q

how do insects injure plants

A

they can pass on the disease

direct injure it by directly feeding on the plant tissue

61
Q

how can insects directly injure plant tissues

A
  • sucking on the plant juices from the leaf
  • girdling the stem (damages the vascular tissue)
  • chewing on the leaves, flowering parts, developing seed
62
Q

what are some factors that contribute to how well a plant will recover from insect damage

A
  • insect population
  • plant growth stage
  • growing condition
  • weather
63
Q

how does insect population affect the damage insects can do on plant

A

the greater the population size the more and faster the damage will be done

64
Q

how does the plant growth stage affect the damage insects can do on plants

A

smaller plants suffer more than large plants. older plants ofter recover better (if they can)

65
Q

how does the plant growing conditions affect the damage insects can do on plants

A

good growing conditions lessen the effects on the insect injury. plants are able to attempt recovery if conditions are good for growth

66
Q

how is weather a factor for if plants can recover after insect damage

A

some insects function better at different temperatures. some like hot conditions best. often cool or cold temperatures result in insect inactivity

67
Q

what is the cyclical nature of insects

A

damage occurs in a cycle related to the life cycle of insects. it may be the larva that does damage or the adult or in some cases both.

some insects have several generations per year others only have one. some insects stay in a stage for many years.

the population is also cyclical as well. the population build-up is a problem and then are reduced by natural parasites or diseases
environmental conditions play a major role in the build-up and decline of insect populations

AGRC 111 (39 decks)

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