Final Exam Flashcards
What are the two ways plants grow?
-Cells can divide
-Individual cells can grow larger
What is plant DEVELOPMENT?
change in phase of life or change in life process
What factors influence plant development?
-genetic
-environmental
-hormones
What are the stages of plant development?
Seed Germination, Vegetative Growth, Reproductive Growth, Senescence
Seed Germination
*Inbibition–a dry seed soaking up water
*increase in biological activity–all sorts of biochemical processes begin, hormones and enzymes become active
*radicle growth–to absorb more water
*cotyledon emerges
*cell division begins and primary shoot as well. as first true leaves are growing
Vegetative Growth
-Shoot Growth
-Root Growth
Reproductive Growth
*flowers and fruit develop
-this may be done during or at the end of vegetative growth, depending on the plant
Senescence
loss of leaves and/or plant death
What are the three possible growth patterns of plants?
Annuals, Biennials, Perennials
Annuals
*complete vegetative and reproductive cycle in one growing season
-usually herbaceous plants
Biennials
*perform vegetative growth the first year and sexual reproductive growth the second year
-many are only grown annually
Perennials
live many years and reproduce several years out of their life cycle
What are the two ways plants can reproduce?
*sexual–seed
*asexual–through vegetative structures
Remember: Many plants can reproduce both sexually and asexually. What are the pros and
cons of each?
Sexually Pros: Genetic Variation
-seeds can survive long periods of dormancy/adverse conditions
-seeds can spread a long way
-adapt to new weather, pests
Asexually Pros: No pollination reliance
-if adapted to current conditions, all offspring will be adapted
-less energy intensive for the plant
Describe the process of pollination.
-pollen (male gamete) landing on the receptive stigma of a flower
-insect, vertebrae and wind pollination
Describe the process of fertilization.
*process of nuclei from the pollen traveling down to the ovary to fertilize the egg
*several nuclei are involved–double fertilization
-2 nuclei are in pollen
-3 nuclei are in egg
*1 nucleus from pollen builds pollen tube down to ovary
*1 nucleus from pollen combines with 1 from egg to form zygote
*other 1 nucleus from pollen combines with 2 remaining nuclei from egg–forms endosperm
*endosperm is food storage tissue for egg–high in carbohydrates for germination
Describe the process of fruit development.
*in many plants, only a small percentage of flowers develop into fruits
-some dont become pollinated
-some dont become fertilized
-some abort after fertilization
*very complex processes, some will not understand
*several plant hormones are involved
*For farmers–sometimes need to find right balance of furit–not too little and not too many
-larger=less fruit
-smaller=more fruit
*undergo a period of rapid division, followed by rapid expansion
*starch accumulates & cells continue to expand
*starch remains or breaks down into sugars as ripening occurs
What do plant hormones do?
act as signaling compounds that tell the plant to begin, increase, decrease or cease any processes
What processes might this include?
-cell division
-entering dormancy
-starting reproduction
-seed germination
-root formation
-cell & tissue death
T/F: can the same group of hormones act on plants in multiple different ways, depending on where and when in the plant they are produced?
True
What are the criteria for plant hormones?
*be endogenous–produce within the plant
*be an organic compound (carbon-containing)
*be present in low concentrations
*able to be translocated through the plant
*not a plant nutrient
*plant growth regulators–mimic of naturally produced plant hormones (we apply them to plants in AG)
What are the 5 main plant hormones?
*Auxin
*Giberrelin (s)
*Cytokinin (s)
*Abscisic Acid
*Ethylene
Auxin
*stimulate cell growth–used as rooting hormones in nurseries
*responsible for apical dominance–plants ability to grow/stand upright
*responsible for phototropism–how plants bend towards light
*responsible for thigmotropism–growth of a plant around an object
*certain synthetic auxins (2, 4-D)–used as a herbicide, causes uncontrolled cell division and eventual plant death
Gibberellin
responsible for:
-stem growth
-transition from juvenile to adult phases of perennials
-floral initiation
-sex determination
-seed germination
*sometimes added with seeds or certain plant species that are hard to germinate
*Gibberellin inhibitors are sometimes sprayed on ornamental plants to keep them compact
*Sprayed on certain fruits to increase size
Cytokinins
*promote cell division–cytokinesis
*stimulates shoot initiation in tissue culture
*delays leaf senescence
*suppresses root growth
Ethylene
*promotes fruit ripening and abscission
*enhances leaf and flower senescence
*induces lateral cell expansion
*some plants ripen with ethylene exposure
USED TO:
-ripen fruits/veggies
-thinning agent
-induce flower drop
STIMULATED BY:
-fruit ripening
-flower senescence
-auxin
-wounding
-chilling injury
-drought stress
-flooding
What are some of the other minor plant hormones?
*Brassinosteroids
*Jasmonic Acid
*Salicylic Acid
*Systemin
What is the difference between climate and weather?
*rain, snow, wind= long-term –> climate
*rain, snow, wind= short-term –> weather
What climactic factor is the most important in deciding what crop to plant or where?
Temperature: temps higher/lower than normal can cause crop reduction or total loss
What climactic factor is the hardest to manipulate on an agricultural scale?
Temperature is the hardest to manipulate on an ag scale
-easier to increase temp than decrease
What are the ways we can manipulate temperature in the field?
Increase Temperature, Decrease Temperature
Increasing Temperature
*inversion fans (wind machines)
*heaters (smudge pots)
*irrigation–irrigation frost protection –> as water freezes it produces heat
*frost cloth
Decreasing Temperature
*Irrigation –> overhead irrigation
What is temperature determined by? Which is the most significant?
*solar radiation –> most signifciant
*proximity to bodies of water
*wind patterns
What are the important results of solar radiation?
helps plants perform photosynthesis
What wavelengths of light are absorbed by plants for photosynthesis? Which are not used
(reflected)?
*plants absorb light at the blue and red wavelength of the color spectrum
*they do not absorb green light wavelengths and reflect them back (which is what makes plants grow)
Do all plants require full sunlight?
*most plants require full sunlight–>the greater the photosynthetic capacity
*some plants have adapted to specific light conditions ex: low light conditions
What is photomorphogenesis?
the ability of plants to sense and grow towards light
What are methods used to increase light to plants?
*pruning
*plant spacing
*row spacing
*trellises
*reflective film and mulch
What are methods used to decrease light to plants?
*pruning, but in different ways
*shade cloth/netting–common for berries, blackberries and blueberries
*sunscreen sprays (such as surround)
What are the types of precipitation?
*dew
*mist
*fog
*rain
*hail
*snow
Why do plants need water?
-cannot perform photosynthesis without water
-will wilt and die without it
What is turgor pressure?
Turgid Cell:
-water enters by osmosis, vacuole swells and pushes against cell wall
Flaccid Cell:
-water lost from cell, vacuole shrinks, cell loses shape
Percentages of earth’s water:
Groundwater-0.3%
Fresh water (lakes and streams)-0.01%
Atmospheric water (rain and snow)-0.001%
What is evapotranspiration?
the combination of water lost as evaporation from land and water surfaces and as transpiration from plants
What is evaporation?
water loss from the surface of soil
What is transpiration?
*water is absorbed by the roots
*water travels up through the plant
*water vapor lost from leaf pores
*releases water vapor and oxygen
Why is evapotranspiration important in farming?
*tells us if there is enough water in the soil or if we need to irrigation
evapotranspiration > precipitation = need to irrigate
What factors go into calculating evapotranspiration?
*temperature
*relative humidity
*transpiration of a reference crop (turf)
*factor to correct for different crops
What are plant stomates?
*pores that open/close to let in carbon dioxide or let out water vapor and oxygen
When rain hits the surface of soil, it can either ____________________________________
or ____________________________________________
absorb into the soil and go into groundwater; runoff the surface into surface water
Why do we heavily rely on irrigation in the Central Valley?
not enough precipitation; way more exapotranspiration
Methods of Irrigation
Surface, Sprinkler, Center Pivot/Linear, Microirrigation
Surface Irrigation
most efficient when having the right soil
Furrow:
-water is funneled into lower parts of “grooves”
Flood:
-flood entire crop area
Sprinkler Irrigation
least efficient form of irrigation–most water loss
Center pivot/linear irrigation
-very common in the midwest or some parts of pacific northwest
-one long pole in center with sprinkler, pivots in circle
Microirrigation
-if designed and maintained correctly, a more efficient use of water than any other method
-most efficient
Nutrients Required for Plant Growth: Non-Limiting
Carbon, Oxygen, Hydrogen
Nutrients Required for Plant Growth: Macronutrients (most commonly deficient)
Nitrogen, Phosphorous, Potassium
Nutrients Required for Plant Growth: Secondary Macronutrients (not commonly deficient–naturally obtained)
Calcium, Magnesium, Sulfur
Nutrients Required for Plant Growth: Micronutrients (needed in smaller amounts)
Chlorine, Iron, Zinc, Manganese, Boron, Copper, Molybdenum
Why is soil important to plants?
provide:
-nutrients
-water
-anchorage
What are the components of soil?
-25% air
-25% water
-45% Minerals (clay, sand, silt)
-5% OM
What is a soil profile?
*good way to study the make up of soil
*a vertical section in the soil to look at layers that have accumulated over time and are currently present in the soil
*each layer is known as a horizon
What are the three soil particle sizes? Which is smallest and which is largest?
Sand: largest
Silt: medium
Clay: smallest
What is soil texture?
the relative proportion of sand, silt, and clay in a soil
How is soil acidity or alkalinity measured?
Acidic: pH below 6.5
Neutral: between 6.5 and 7.0
Alkaline: pH above 7.0
*measured in a logarithmic scale
-pH 6 is ten times as acidic as pH 7
-pH is one hundred times as acidic as pH 8
What does soil pH influence?
-nutrient availability
-solubility of toxic ions
-microbial activity
How do you change soil pH?
Lower (make more acidic) or higher (make more alkaline
How to lower soil pH
*elemental sulfur
*the calcium and magnesium carbonate (free lime) found in many western soils acts as a buffer against the development of acidic soils
How to raise soil pH
calcitic or dolomitic lime can be used to raise soil pH
What is cation exchange capacity?
*an important measure of soil fertility and potential productivity of the soil
*clay particles and soil OM have a net negative charge. Positively charged ions (cations) can be attracted to and held onto the surface of these materials
What does cation exchange capacity influence?
influences how much of a cationic nutrient can be held in the soil
Soil particle/substance with Low CEC
Sand
Soil particle/substance with Moderate CEC
Silt
Soil particles/substances with High CEC
Clay and OM
How does sodium affect soil?
soils high in sodium ions are dispersed and resist water infiltration
How does calcium affect soil?
soils with higher percentage of calcium are well aggregated and have high infiltration rates
What are the benefits of soil organic matter?
-serve as a food source for living organisms in the soil; they break down organic matter
-helps strengthen soil aggregates
-improves aeration and water infiltration
-increases water holding capacity
-provides buffering against rapid changes in soil reaction when acid or alkaline-forming materials are added to soil
-forms stable organic compounds
What nutrients does soil organic matter provide?
-Nitrogen
-Phosphorous
-Sulfur
decomposition of 1% of OM in the soil releases 30-60 lbs of Nitrogen per year
What is a pest? Why are pests a problem?
*organisms that reduce the availability, quality or value of a human resource
*compete with people for food or fiber, interfere with raising crops or livestock, damage property, tarnish ornamental planting, transmit disease, invade our water ways or nautral areas
Give 3 examples of different pests.
insects, rodents, birds, fungus, weeds, bacteria, viruses
List and describe the three pest management strategies.
- Preventative
-discourage pest population from developing - Suppressive
-reduce population from developing - Eradication
-totally eliminating a pest from a designated area–used when no pest can be tolerated
List and describe the three different classifications of pests.
*key pests-cause major damage on a regular basis unless they are controlled (codling moth in walnuts)
*occasional pests–become intolerable regularly
*secondary pests–occurs as a result of actions taken to control a key pest
List and describe the basic components of an IPM program.
*Inspection and Monitoring
*Identification
*Weather forecasting
*Plant according to thresholds
*Implement IPM Tactics
*Record-Keeping
*Evaluate effectiveness
What is the best IPM resource to get started with a pest management program?
UC IPM
What are the pest controls utilized in an IPM program?
Genetic Resistance, Cultural, Mechanical/Sanitation, Biological, Chemical
Genetic Resistance
*most sustainable pest control
-use cultivars of plants that are resistant or tolerant to pests that are present
Cultural
-any method of modifying growing techniques
ex:
-crop rotation
-adjust planting dates
-adjust plant density
-pruning to improve air flow
Mechanical/Sanitation
-don’t move soil from one location to another
-clean pruners/equipment
-tilling under diseased/infested fruit or nuts
Biological
Classical Biocontrol:
-the use of a living organism to control a pest
-introduction of a non-native organism to control a pest (usually from the same location as the pest)
Conservation Biocontrol:
-practices to keep biocontrol you do have content
-avoid use of broad spectrum pesticides
-provide forage (flowers, etc.) for biocontrols
Augmentative Biocontrol:
-reintroduction of a native biocontrol if populations were disrupted
Chemical
-insecticides, herbicides, fungicides
-use them when there are no other effective controls
-always have to rotate between modes of action to prevent resistance
T/F: Energy usage is expected to increase faster than population growth because of economic development
True
What is a fact?
a proposed explanation for a phenomenon
What is a theory?
observation about the world around us
What is a hypothesis?
a statement based on repeated experimental observations
What is a law?
an explanation acquired through the scientific method
Abscisic Acid
*actually has little to do with abscission
*stimulates stomatal closure
*induction and maintenance of bud dormancy
*inhibits gibberellins from stimulating the conversion of starch into sugars–inhibits seed germination
