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