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23 Cards in this Set

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  • Back
What are the 5 roles of the seed?
1) multiplication of the species
2) provide dispersal
3) food for embryo
4) protects embryo from adverse conditions
5) maintain diversity
What is weeds'production potential when compared to crops?
the crop will ususally outcompete but weeds make up for it by producing a lot
What is in a weed seed bank?
1) lots of species
2) tremendous numbers of seeds
3) different levels of dormancy
What influences the size of the weed seed bank?
tillage, crops/rotation, management
What is the safe-site concept and what influences it?
only a fraction of seeds are goin to come up at one time
Influenced by:
Number of seeds
What is dormancy?
the ability of seed to sit in a resting state waiting for the right conditions to germinate
What is vivipary?
when innate dormancy doesn't work and causes germination on the mother plant
What are the 3 types of dormancy and their mechanism?
1) Innate--keeps seeds from germ. while forming due to a chem. inhibitor
2) Enforced--env. conditions have to ideal to germ.
3) Induced--enforced + chem. inhibitor or some other mech that prevents germ. even under ideal conditions
Name 2 mechanisms of maintaining dormancy.
1)physical--hard seed coat
2)morphological--not fully mature
3)physiological--chem. inhibitor that has to be leached out
What is going to have a greater influence on weed presence--seed bank dynamics or influx of external seed?
influx of external seed b/c if weeds with induced dormancy go to seed they can be in there for years compared to innate which come up every season.
What is the plant pigment that is involved in light responses in plant (red-far-red ratio)?
What factors affect germination?
1) depth of burial
2) soil factors
3) seed shape
4) moisture
5) temperature
6) oxygen
7) light
8) pH and minerals
What are the (dis)advantages of using burial for management?
Adv: most grasses and small seeded can be controlled
Disadv: will work the 1st year but the 2nd year the soil is flipped back over and can germinate if it has dormancy
What soil factors affect germination?
microtopography-surface of soil
soil type
How does the seed shape affect germination?
small and smooth seed slides down into a crack
large and rough seed increases surface area
How can knowing a weed's osmotic potential affect management?
know if you can use saltwater as a management technique
Why is rice grown in water?
to eliminate weeds b/c most weeds need O2
What type of light does dogfennel need and why?
red b/c it is so small that it needs to be near the surface
The weed seed bank contains various numbers of weed species and includes dormant seeds. TRUE or FALSE
What factors influences how long a seed can last in the soil and still be viable?
composition of seed coat
metabolism, microorganisms and env. factors
Name 2 specialized vegetative structures.
Tubers, turions
Explain about vegetative structures.
Usually stem tissue
k strategy perennials
structure for maintaining bud/meristem
asexual reprod. only
What nutrient will stimulate germination?