seeds

Question 1

what is the dormancy cycle of a seed

Answer 1

1. Starts at primary dormancy. As the seed is actively growing one or more dormancy mechanisms may be initiated within the seed and take effect to stop the seed germinating on the parent plant
2. Quiescence is the second stage and is a gradual release from primary dormancy. It’s a non-dormant state where growth is not occurring simply because one or more of the basic environmental factors are absent. The seed will germinate if water, oxygen, and suitable temperature are present.
3. secondary dormancy is induced in seeds by environmental factors other than those experienced on the mother plant.

Question 2

what is and apart of imposed dormancy

Answer 2

the seed is dormant because of some constraint imposed on the embryo by the tissue around it

1. hardseededness. The coat is impermeable to water, will only become permeable to water if seed coat is scratched
2. after ripening. seeds that don’t require environmental stimuli to break dormancy but a period of storage to complete development.

Question 3

what is and involved in true dormancy

Answer 3

dormancy is a function of the embryo. a specific environmental stimulus is needed for germination the two types are

light

or temperature is also known as stratification requirement

Question 4

what is the role of phytochrome in seeds

Answer 4

phytochrome exists in two forms

it causes a series of events that result in dormancy breaking

Pr and Pfr go round in circles

Question 5

what are the dormancy mechanisms

Answer 5

Imposed dormancy is the inhibition of germination due to factors outside the embryo

true dormancy situation where embryo itself is metabolically incapable

Question 6

what is after ripening

Answer 6

seeds require a period of storage before germination rather than any environmental factor.

Question 7

what is a germination inhibitor

Answer 7

chemical or other inhibitors within the embryo the inhibit germination

Question 8

what is impermeability to oxygen

Answer 8

a seed coat can be impermeable to gasses such as oxygen

usually due to a chemical inhibitor

Question 9

what is physical constraint of embryo growth

Answer 9

The seed coat or surrounding tissues may also prevent germination by physically constraining the growing embryo

Question 10

what is Primary dormancy

Answer 10

the sum effect of dormancy mechanisms established in the mature seed during development on the plant

Question 11

what is quiescence

Answer 11

gradual release from primary dormancy. It’s a non-dormant state where growth is not occurring simply because one or more of the basic environmental factors are absent. The seed will germinate if water, oxygen, and suitable temperature are present.

Question 12

what is relative dormancy

Answer 12

Dormancy relative to the dormancy mechanisims experienced

Question 13

what is secoundary dormancy

Answer 13

dormancy induced by environmental factors

Question 14

what is stratification

Answer 14

seeds that require exposure to low temperatures to break dormancy

Question 15

what is temporal dispersal

Answer 15

provides means of preventing germination until after winter has past

Question 16

what is the seed bank

Answer 16

the sum total of all viable seed is called the seed bank

Question 17

what is seed pelleting

Answer 17

Palleting alters the shape of the seed. it can add volume and increase precision

Question 18

what is film coating

Answer 18

pesticide or beneficial organism is added as a thin polymer-coating.

coating doesn’t rub off

Question 19

seed coating should deliver any of the required

Answer 19

pesticides,

mineral nutrients

plant growth regulators

beneficial microorganisms

Question 20

what is encrusted coating

Answer 20

doesn’t obscure shape of seed contains micronutrients, fungicides, and insecticides

Question 21

what does Trichoderma spp do

Answer 21

help control disease when added to a seed coat

helps with damping off

Question 22

what are the types of seed coating available

Answer 22

encrusting

palleting

film coating

Question 23

what is the key factor that distinguishes a palleted seed from a seed that is film-coated

Answer 23

film-coated keeps the shape of the original seed

the palleted seed will be round and uniform

Question 24

why chose palleted seed rather than film coat it

Answer 24

facilitate precision sowing of seeds

protection of seed

Question 25

what are biocontrol agents and how do they relate to seed coating

Answer 25

seed treatment used to control pests

includes fungal strains such as Trichoderma which helps with damping off

Question 26

why is production location important for a seed crop

Answer 26

the choice of production ares is dependant on climate, vernalisation and photoperiod requirements.

a crop may have specific requirements, vernalisation or day length (photoperiod)

a seed producer can manipulate the production system through sowing dates and can have flowering and seed filling at the most favourable time of year

Question 27

important factors of field selection and preparation

Answer 27

cropping history is important

the area must be clean from weed seeds

and distance from other crops

field prep should remove weed species by chems or tillage

deficiencies in soil need to be remedied

Question 28

important factors of seed and variety selection

Answer 28

seed should be of high quality so establishment is good

demand selects variety however where possible grow varieties that have an advantage for production in that area

Question 29

important factors of sowing and establishment

Answer 29

date sowing as early as possible

sown direct or transplant may need staggered planting for m/f

plant density: need air movement to reduce disease and flower development

Question 30

important factors of irrigation

Answer 30

avoid moisture stress during establishment and early seed development

dry is needed when the crop is maturing

Question 31

important factors of pollination for vege seed production

Answer 31

pollinators required

reduce cross-pollination via isolation distance

cages to keep wind but stop insects

remove weeds that can cross-pollinate

Question 32

problems with weeds in seed production

Answer 32

compete with seed crop for water, light and nutrients

interfere with cultivation and harvesting

may harbour pests and diseases

may produce seed that is similar to size and shape to crop seed.

Question 33

important factors of disease control in seed production

Answer 33

low relative humidity

away from fresh market production

crop-rotation

foliar sprays

Question 34

important factors of insect control when producing crops

Answer 34

insecticides if needed

Question 35

important factors for harvest in seed crops

Answer 35

harvest at right time to early, immature seed too high moisture = lower storage capabilities and quality

delayed harvest can lose yield to crops which disperse their seeds and or birds

avoid contaminating seed lot

Question 36

important factors of cleaning and storage with seed prod

Answer 36

cleaned to remove contaminants

some seeds need to have appendages

should not be used as a substitute for good seed production

stored at conditions to maintain seed quality and keep dormancy

Question 37

important factors with quality assessment when producing seed crop

Answer 37

the final step is to verify seed has met quality standards

done my seed lab

Question 38

what are the key steps that have potential for limiting yield or quality in a seed crop

Answer 38

1. production site selection
2. establishing the crop
3. getting the crop to flower
4. getting seed set
5. getting the seed from fertilisation to harvest
6. harvesting, processing and storing