Seed Germination and Vegetative Repro

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Transcript of Seed Germination and Vegetative Repro

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Conditions For Germination

• Conditions required for germination are the presence of:

(a) water

(b) air

(c) suitable temperature (heat)

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WATERWater - is required for germination. • Mature seeds are often extremely dry and

need to take in significant amounts of water, relative to the seeds dry weight, before cellular metabolism and growth can resume.

• Most seeds respond best when there is enough water to moisten the seeds

but not soak them.

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2. Temperature – • warmer temperatures enable

enzymes to work.

3. Air (Oxygen) - enables seeds to respire

aerobically to supply energy for growth

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Vegetative organs are stems, leaves, and

Roots.– Modification of vegetative organs make

vegetative reproduction (asexual) possible

How Do Angiosperms (flowering plant) Reproduce

Asexually?

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Vegetative Reproduction• Is a type of asexual reproduction that produces

a new plant from a certain part of the parent plant without involving seeds.

• Occurs through certain parts such as:

~ Rhizome ( Rizom)

~ Leaf ( Daun)

~ Tuber ( Tuber)

~ Stem ( Batang)

~ Runner ( Batang Rayap)

~ Bulb ( Bebawang)

~ Corm ( Umbisi)

~ Sucker ( Anak Pokok)

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TubersTubers are underground food stores which stores food over the winter and provides a new plant with food until it can make its own.

Food made by the new plant is sent to make new tubers. Thereby reproducing itself.

Examples: potato, artichoke, yam, cassava, water chestnut, arrowroot

Taro- Japanese potato

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• Some form enlarged underground stems called tubers (e.g., potatoes).

• They develop when specialized stem branches grow down into the ground and swell up with starch containing cells.  Buds on the tubers will grow into new plants.  Examine the potato tuber and note the buds which are commonly termed "eyes" (Figure 7).

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Bulbs • Onions, chives and lilies over-winter in the form of a bulb. 

• Each bulb has a very short stem which is surrounded by fleshy leaves.

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– Bulbs and corms are short, vertical, underground stems.

• Bulbs have fleshy, modified leaves for food storage — a large, underground bud. These can give rise to new plants, (lilies, onions).

Bulb of Hippeastrum lily

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Bulbs

• E.g. daffodils, lilies

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Runners- Stolons

Runners are side shoots which grow out from the parent plant.

Buds form at points along the runner and eventually these buds form roots and grow into new plants.

Examples: spider plant (Anthericum), strawberry (Fragaria x ananassa)

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Runner

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Runners (Stolons)

• These are horizontally growing stems that produce few, if any, leaves. 

–horizontal stems that form roots –at intervals and can develop into new plants

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– Rhizomes are horizontal underground stems that give rise to new shoots.

www.texasbamboosociety.net

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Corms

• This structure is similar to bulbs except that there are no storage leaves.

• The nutrients are, instead, stored in the swollen stem. 

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• Corms – disc-like underground stems that consist primarily of stem tissue.

www.backyardnature.net/pix

Corms of crocuses (left) and gladiolus (right)

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– Leaves can also be source of new plantlets, as in Kalanchoe.

Vegetative reproduction: Plantlets form at edge of leaf

of Kalanchoe daigremontiana.

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– Suckers • are shoots produced by

roots. • Many grasses and trees,

such as aspens form interconnected stands of genetically identical individuals.

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Application of Vegetative Reproduction

• vegetative reproduction technology includes:

(a) cutting (keratan)

(b) marcot (tut)

( c) Layering ( tut lentur)

(d) tissue culture ( Kultur tisu)

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Cuttings

• Cuttings: Cuttings are part of the plant that is cut off of the parent plant. Shoots with leaves attached are usually used. New roots and leaves will grow from the cutting. The shoot is cut at an angle. A growth promoter may be used to help with the growth of the roots.

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Cutting

They can be placed in moist

soil or water (and sometimes

dipped in rootingpowder).

Cuttings are small pieces of stem with some leaves attached, the new plant grows from this.

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MARCOT (TUT)

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Layering

•    Layering: In layering a shoot of a parent plant is bent until it can be covered by soil. The tip of the shoot remains above ground. New roots and eventually a new plant will grow. These plants can then be separated.

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Researchers are investigating ways to reproduce plants by tissue culture.– Many plant cells are tot potent — undifferentiated

cells can give rise to entire plants– Culturing tiny bits of apical meristem can eliminate

plant viruses

www.ppm4plant-tc.com/ http://members.tripod.com/~rsauleda/

Cattleya orchid

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– Treatment with hormones can cause apical meristems to produce millions of plants in a year

– Used for strawberries and potatoes to produce virus-free plants

http://www.noursefarms.com/images/staticPages/tour/tissueCulture.jpg

Tissue culture of commercial strawberries

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Recombinant DNA also used with tissue culture to produce plants with disease resistance, increased nutritive value, etc.

www.goldenrice.org/image/

Golden Rice (right) is bioengineered to produce and accumulates pro-vitamin A (β-carotene) in the grain, often in short supply in developing countries.