Seed Germination and Propagation

Different types of bulbs

Tunicate or scaly, aerial or underground, spring/summer flower, or winter flower.

Definition of a seed

A mature ovule resulting from sexual fertilization that contains an embryo, storage tissue, and a protective outer covering.

Three parts of a seed

Embryo, storage tissue, and seed coat

5 advantages of asexual propagation in plants

Uniformity, propagate non-seed producing plants, avoid seed-borne diseases, create insect or disease resistance, and control size and form of a plant.

Differences between sexual and asexual propagation

Sexual propagation involves seed germination, while asexual propagation involves vegetative parts or tissue culture.

Double fertilization

One sperm cell fuses with the egg to form the embryo, while another fuses with polar nuclei to form triploid tissue that nourishes the seed.

Microsporogenesis

The process of pollen development through mitosis.

Megasporogenesis

The process of ovule development that produces four daughter cells, three of which are aborted.

The role of the funiculus in seed development

It connects the seed to the mother plant.

Difference between gymnosperms and angiosperms

Gymnosperms have naked seeds without covered ovaries, while angiosperms are flowering plants with a seed covering ovaries.

Cotyledons

The first two bottom leaves that appear from a seed, which may store nutrients.

3 methods of seed dispersal

Wind carrying structures, sticking to animals, or having food on the outside

The purpose of tissue culture

To propagate plants either sexually or asexually

Pollination

The first step before seed formation, leading to fertilization.

Aril seeds

Seeds that are not enclosed in a seed coat, like a pomegranate.

Ovule

It develops into a seed after fertilization.

Ovary

It develops into the fruit after fertilization.

3 steps of seed development

Histodifferentiation, cell expansion, and maturation drying.

Histodifferentiation

The fruit develops all the cells it needs during seed development.

Cell expansion

How the fruit gets big during seed development.

Maturation drying

Involves storage reserves, including protein reserves that surround the embryo. (during seed development)

Endosperm

It provides nutrients, but some plants don’t have it.

Orthodox seeds

Seeds that are desiccation tolerant and can resist drying.

3 examples of orthodox seeds

Corn, beans, and rice.

Recalcitrant seeds

Can not tolerate maturation drying and need to be stored in a moisture-rich environment.

3 examples of recalcitrant seeds.

Acorns, chestnuts, and camellia seeds.

Precocious germination

It is when seeds germinate inside the fruit, like tomatoes.

Apomixis in seed development

A form of asexual reproduction that can include non-recurrent and vegetative.

4 Hormones that impact seed development and germination

Auxin, GA, cytokinin, ABA, and ethylene.

Three conditions necessary for seed germination

Seed viability, appropriate environment, and primary dormancy.

6 methods for testing seed viability

Cut tests, float tests, tetrazolium staining, germination tests, paper towel test, and X-ray analysis.

What are the phases of early germination?

Imbibition, lag phase, and radicle protrusion

What happens during the lag phase of germination?

Chemicals convert to usable materials for seed; mitochondrial maturation and protein synthesis.

What is the role of ABA and GA hormones in seed germination?

ABA suppresses seed germination when too high, while low ABA and increased GA promote germination.

What is the difference between epigeous and hypogeous germination?

Epigeous germination has cotyledons above ground, while hypogeous germination has cotyledons remaining underground.

2 examples of epigeous germinated plants

Beans and okra

What are the measures of germination to discuss in a lab report?

Percentage of seeds germinated, speed (rate) of germination, and uniformity.

What environmental factors influence seed germination?

Temperature, light, and water.

What is thermoinhibition?

Germination inhibited by high or low temperature.

What is seed priming?

A pre-germination treatment to prepare seeds for germination while preventing actual germination until ready.

What are the three stages of seed priming?

Osmotic priming, matrix priming, and drum priming.

What is an advantage to seed priming

Good germination percentage

What is a con of seed priming?

Concerns about how long seeds can be stored

What is the difference between orthodox and recalcitrant seeds?

Orthodox seeds can tolerate mature drying and can be sored in room temp for longer periods while recalcitrant seeds can not tolerate mature drying and need to be stored in cold moist environments.

What is seed dormancy?

A condition where seeds do not germinate even when environmental conditions are favorable.

What is primary dormancy?

Regulation of germination that can be exogenous or endogenous.

What is seed provenance?

The geographic source or location from which seeds are collected.

What is damping-off in relation to seed germination?

Disease control during seed germination that requires a clean environment.

What is a key difference in genetic makeup when collecting seeds from the wild?

The genetic makeup is very different, leading to non-uniform germination.

Can pure and uniform seeds be produced from woody plants in the wild?

No

What 3 factors affect seed storage longevity?

Cold temp, low moisture, and sealed containers.

What are 3 examples of recalcitrant seeds?

Buckeye, camellia, and oaks.

What are the 3 breeding systems used in seed propagation?

Self-pollination, cross-pollination, and apomixis.

What is the purpose of seed treatments?

To improve germination and protect against diseases and insects.

Scarification

A physical process that allows water to penetrate seeds with a hard seed coat.

Stratification

A chemical process involving a period of moist-warm or moist-cold conditions to break dormancy in seeds.

What is the role of coated seeds?

They have altered shapes that make them easier to sow with precision seeding machines.

What is purity percentage in seed production?

It indicates the proportion of pure seeds in a batch.

What is the field factor in seed production?

It refers to the weight of seeds to sow per unit area.

What is plug production in transplant production?

Using small celled transplant flats to produce many seedlings in a small greenhouse.

What is a cold frame used for in transplant production?

Used for hardening-off by using passive solar heating to protect transplants.

What are 5 techniques to maximize transplant production?

Germination facility, substrate management, mechanical seed sowing, water systems, and temperature control.