Lecture 5: Seed Production

Question 1

Advantages of seed propagation

Answer 1

1. genetic diversity(variation)
2. relatively inexpensive
3. convenient for storage
4. disease free propagation

Question 2

Disadvantages of seed production

Answer 2

1. genetic diversity(not genetically uniform)
2. time to maturity

Question 3

Where do seeds come from?

Answer 3

1. self-pollination
2. cross-pollination
3. apomixis

Question 4

self pollination

Answer 4

1.occurs when pollen fertilizes flower or flower from the same plant
2. results in fixed homozygosity over time

Question 5

cross pollination

Answer 5

1.occurs when pollen from one plant fertilizes another
2. results in increased heterozygosity

Question 6

apomixis

Answer 6

1. means “without mixing”
2. occurs when an embryo is produced from a single diploid cell of the sporophyte and not from fertilization
3. results in a seed that is genetically identical to the mother plant

Question 7

Seed coat

Answer 7

develops from the integuments of the ovule that becomes dry and hardened

Question 8

embryo

Answer 8

becomes the plant

Question 9

endosperm

Answer 9

nutritive tissue, protects some embryos

Question 10

cotyledons

Answer 10

seed leaves

Question 11

epicotyl

Answer 11

section of seedling stem above cotyledons

Question 12

Hypocotyl

Answer 12

section of seedling stem below cotyledons

Question 13

radicle

Answer 13

growing point of the root

Question 14

plumule

Answer 14

growing point of the shoot

Question 15

Stages of Seed Development

Answer 15

1. Histodifferentiation
2. Cell expansion
3. Maturation drying

Question 16

Stage 1: Histodifferentiation

Answer 16

characterized by the differentiation of the embryo and endosperm

Question 17

Step 2: cell expansion

Answer 17

characterized by rapid cell enlargement due to accumulation of storage substances

Question 18

Stage 3: Maturation dying

Answer 18

1. seed is physiologically mature
2. high germination potential, maximum dry weight reached, rapid water loss

Question 19

Vivipary

Answer 19

when seeds germinate without maturation or drying while still within the fruit attached to plant

Question 20

Vegetative parthenocarpy

Answer 20

fruit develops without pollination

Question 21

Stimulative parthenocarpy

Answer 21

fruit develops after pollination but does not require fertilization

Question 22

parthenocarpy

Answer 22

fruit development without seed formation

Question 23

Orthodox seed

Answer 23

dry at maturity and usually can be stored for years in a dry state

Question 24

recalcitrant seeds

Answer 24

1.do not tolerate drying at maturity
2. if they dry too far, they lose viability and/or die

Question 25

Primary dormancy

Answer 25

seeds cannot germinate even if immediate environmental conditions are ideal

Question 26

Secondary dormancy

Answer 26

an additional level of protection to prevent germination

Question 27

Exogenous

Answer 27

imposed by factors outside the embryo
i.e. seed coat

Question 28

endogenous

Answer 28

imposed by factors within the embryo

Question 29

double

Answer 29

combination of dormancy conditions that need to be sequentially broken

Question 30

Types of primary

Answer 30

1. exogenous
2. endogenous
3. double

Question 31

Three Phases of Germination

Answer 31

1. Water uptake
2. Lag Phase
3. Radicle emergence

Question 32

Phase 1: Water Uptake

Answer 32

1. first 10-30 mins-rapid uptake
2. followed by 1-10 hours of slow uptake
3. seed volume increases

Question 33

Phase 2: Lag Phase

Answer 33

1. mitochondria mature
2. proteins synthesized
3. storage reserves metabolized
4. enzymes loosen cell walls

Question 34

Phase 3: Radicle Emergence

Answer 34

1. result of cell enlargement
2. enzymes degrade specific cell walls to allow the radicle to exit
3. GA promotes cell wall hydrolysis and radicle emergence

Question 35

Direct seeding

Answer 35

seeds are planted where the plants will grow to maturity or harvest

Question 36

Indirect seeding

Answer 36

seeds germinated in greenhouse then placed in field