August 2008

Plant Life Cycles

Chapter #2

Modified by Georgia Agriculture Education Curriculum Office

June 2002

August 2008

What is a Life Cycle?

• from the time a seed is planted until the time that a seed is produced

August 2008

What are the Life Cycles?

• Annuals, Biennials, & Perennials

August 2008

Annual

• complete life cycle in one growing season– can be summer

annuals (spring wheat, barley) or winter annuals

(winter wheat)

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Biennials

• require two growing seasons to produce seed– first season plant

produces vegetation, second season seed (sugar beet, carrot)

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Perennials

• indefinite growth, can produce seed annually (grasses, trees, shrubs, onion)

August 2008

What is a Seed?

• package containing an embryo (miniature plant) and food

• seeds are alive, need air

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What is Germination?

• process where embryo changes to seedling (growing plant)

August 2008

What conditions are necessary for germination?

1) moisture

2) correct temperature

3) air

4) some seeds need light

5) some seeds need help (break seed coat [sunflower], remove a chemical from seed, heat, chill [winter wheat])

August 2008

What are Warm Season Crops?

• soil temperature must be 70 degrees F or more for germination (corn, rice, cotton, melons)

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What are Cool Season Crops?

• soil temp below 70 degrees F (wheat, barley, beets)

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How deep do seeds need to be planted?

• the size of the seed determines

• larger seed = deeper

• corn = 4"

• bluegrass = 1/4"

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Germination Process

1) seed absorbs water, swells

2) water activates enzymes which help digest stored food

3) root grows

4) shoot emerges (is now a seedling)

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What is vegetative growth?

• plant produces food for itself

• extra food is stored in roots,

stems, etc.

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What is…?

• when new stems are formed in grass plants

Tillering (Stooling)?Tillering (Stooling)?

Jointing?Jointing?• stems of grass plants elongate rapidly

Respiration?Respiration?• process how plants get energy from its

stored food

August 2008

How is food stored in plants?

• form of carbohydrates (sugars)

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How does respiration work?

Food + Oxygen --> Carbon Dioxide + Water + Energy

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What factors can influence the rate of respiration?

1) high temps = high rate of respiration

2) high amounts of light = high rate

3) high amounts of water = high rate

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What is Photosynthesis?

• process of converting water and carbon dioxide into food (sugar) and oxygen in the presence of chlorophyll and light

• photosynthesis and respiration are opposite cycles

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What is Transpiration?

• process of returning water to the air (in the form of gas)

• 99% of water taken in by roots is transpired

• Wilt = plant transpires more than it takes in

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What are Nutrients?

• elements needed by plants to grow

What are Macronutrients?

• needed in large amounts

• C, H, O, N, P, K, Ca, Mg, S)

• plants get C, H, O from air and water

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What are Primary Nutrients?

• N, P, K

What are Secondary Nutrients?

• Ca, Mg, S

• needed less

Nutrients

August 2008

What are Micronutrients?

• needed in small amounts, but essential

• excess amounts are toxic

• Fe, Bo, Mn, Zn, Mo, Cu, Cl

August 2008

16 Essential Nutrients

• C H O P K N S Ca Fe Mg B Mn Cu Zn Cl Mo

• An easy way to help remember essential nutrients is with the help of this sentence (each word or letter stands for each nutrient): C Hopkins Café Managed By Mine Cousin Clomo