Introduction to Plant Reproduction

Objectives: Distinguish between asexual and sexual reproduction of plants; Discuss importance of both types of reproduction in plants; Identify major parts of seeds; Describe process of seed germination.

Define Propagation Propagation The reproduction of plants either sexually or asexually.

Asexual vs. Sexual Reproduction Asexual reproduction involves ONE living organism. Sexual reproduction involves TWO living organisms.

Define sexual reproduction The union of the female and male sex cells to produce a seed (embryo). Ovule: female sex cell. Pollen: male sex cell. Embryo (seed-germ): an immature plant. *Sexual reproduction involves the creation of a genetically new individual.

Define asexual reproduction The reproduction of a plant without the uniting of a pollen and ovule. Asexual reproduction is often referred to as vegetative propagation since no seed is involved in the formation of the new plant. It is known as a clone. Leaves, stems or roots may be used to grow a new plant. *Produces a genetically identical plant.

BRAINSTORM Group A: Brainstorm benefits of asexual reproduction of plants (i.e. vegetative propagation) Group B: Brainstorm benefits of sexual reproduction of plants (i.e. seeds)

Benefits of Asexual Reproduction (Vegetative Propagation) True traits of the parents Maintains genetic purity with 100% replication of parent plant. No seed Some plants do not produce a seed or the seeds are too small to work with. Accelerates the time it takes to get a new plant to the market Traditionally, it would take up to 40 years to get a new plant to the general public; however, micropropagation can yield marketable levels of plants within 8 to 12 years.

Benefits of Sexual Reproduction Genetically new individual created Hybrid created Potential to improve crop traits Seed can be stored

Types of seeds. Monocots: Dicots Seeds with one seed leaf Seeds with 2 seed leaves or 2 cotyledons

Monocots

Dicot

Parts of a Seed Embryo Plant = will become seedling plant Cotelydon(s) Primary Root (Radicle) Embryonic (seed) leaves Endosperm = stored food Seed coat = protective shell

Label a Lima Bean Cut: Label: Carefully cut the lima bean in half; Place the halves on the paper plate. Label: Cut and label tags from the sticky-notes; Stick each label on its own pin; Place the labeled pins in the correct part of the seed.

Pollination, Fertilization and Germination The transfer of pollen from an anther to a stigma of a flower of the same species. Fertilization The union of the pollen and ovule cells. Germination The sprouting of a seed.

Germination Process by which an embryo plant inside the seed changes into a developing seedling. Germination is the end of the period of dormancy Favorable conditions are present for the growth and development of the seedling plant…so it sprouts and starts to grow!

Seed Germination Test The germination rate is a measure of viable seed, or the percentage of seeds planted that sprout. To calculate: The number of live seeds divided by the number of seeds planted equals the germination rate.