The Juvenile Phase and Practical Seed Science

Question 1

What is seed priming?

Answer 1

The process of regulating germination by managing the seeds moisture content, in order to maximise the potential of the seed.

Question 2

State 10 benefits of seed priming?

Answer 2

Faster emergence/ less time between first and last emergence,
Reduced amount of fungi and bacteria on seeds,
Improved uniformity,
Earlier canopy development,
Wider temperature range for germination,
Increased final population,
Optimised harvesting performance,
Compete more effectively with weeds,
Better control over scheduling
More yield and enhanced productivity.

Question 3

Name 4 seed priming methods.

Answer 3

Hydro priming (water),
Halo priming (salt solution),
Osmo priming (solution of sugar, polyethylene glycol, glycerol, sorbitol or mannitol followed by air drying),
Hormonal priming (different hormones- salicylic acid, ascorbate, kinetin, which promote growth and development of seedlings).

Question 4

State 4 disadvantages of seed priming.

Answer 4

Hydro priming can leech nutrients,
Cost,
Knowing when to stop requires skill,
Priming decreases storability/ Cool storage required.

Question 5

State 5 benefits of seed coating.

Answer 5

Frost protection (polyvinyl alcohol),
Pest protection (poisonous coatings, cyanide),
Disease protection,
Rhizobia coatings promote the growth of nodule colonies.
Increase size/ pelleting makes sowing easier.

Question 6

State 2 negative effects of seed coating.

Answer 6

Using neonicotinoids as a seed coat to prevent herbivory has a detrimental effect on bee populations.

The use of chemical seed coats reduces the effectiveness of bio-control.

Question 7

What is seed conditioning?

Answer 7

Improving seed quality through the removal of decayed, broken, insect damaged or low-quality seed.

Question 8

State 5 objectives of seed conditioning.

Answer 8

Minimisation of seed loss,
Removal of contamination and foreign material such as weeds,
Upgrading seed quality by removing insect-damaged seeds,
Efficiency- increase effectiveness of separation,
Minimises labour and saves cost.

Question 9

What is a shoot apical meristem?

Answer 9

A collection of cells at the tip of a growing shoot that can develop into vegetative or reproductive organs, depending on hormonal signals.

Question 10

What are the 3 stages of plant growth?

Answer 10

Juvenile,
Adult vegetative,
Adult reproductive.

Question 11

What are 3 characteristics of the juvenile phase?

Answer 11

Meristems have no ability to produce reproductive growth, they are non-competent to flower.
Plant rapidly increase photosynthetic capacity, size and mass.
Size is attained to support flowering.

Question 12

During which vegetative phase can a plant produce reproductive organs?

Answer 12

Adult vegetative phase.

Question 13

What does ripe to flower mean?

Answer 13

The juvenile phase has been completed but correct conditions for flowering have not been met.

Question 14

What influences differences in morphology and phase changes between juvenile and adult phases?

Answer 14

Hormones such as gibberellic acid,

Nutrients.

Question 15

What are some characteristics of a transition to an adult phase?

Answer 15

Irreversible/ committed,

Signals to growing points can change leaf size and shape.

Question 16

What are the commercial benefits of recognising juvenile/ adult stages?

Answer 16

Scheduling advantages,
Controlling limiting factors in breeding programs,
Windbreaks and hedges can be desirable in juvenile plants which retain leaves in winter.

Question 17

How does vegetative propagation relate to the juvenile phase?

Answer 17

plants propagated by asexual techniques do not have a juvenile phase because the mother plants are mature.
This maturity transfers to offspring, except when the mother plant is juvenile, or has both mature and juvenile growth.

Question 18

What is seed coating?

Answer 18

Application of a coating to make seeds easier to sow, improve quality, protect from stressors and improve efficiency.

Question 19

Name 5 stages of seed coating.

Answer 19

Drying,
Pre-cleaning,
Viability,
Packaging,
Storage.