Chapter #21

Plant Growth and Disease

Chapter 21.1 Notes

• Plant growth happens at the root tips and stem tips.

• Plants only grow longer and taller.

3 types of plants1. Short-day plants are

plants that flower when the day length falls below 12 to 14 hours.

2. Long-day plants are plants that flower when the day length rises above 12 to 14 hours.

3. Day-neutral plants are plants in which flowering doesn’t depend on the length of day. Continually flower until frost.

Poinsettia are short-day plants

Roses are day-neutral plants

Tropism- is a very slow movement of a plant caused by a change in growth as a response to a stimuli.

1. Phototropism- is the growth of a plant in response to light.

2. Gravitropism- is the growth response of a plant to gravity.

3. Thigmotropism- is a plants response to touch or contact (Vines).

Chapter 21.2 Notes• Plants can live a few months to thousands of

years.• 3 plant types

1. Annual plants- complete their life cycle within 1 year. Examples corn, peas, impatiens.

2. Biennial plants produce seeds at the end of the second year of growth and then die. Examples cabbage, turnips.

3. Perennial plants produce seed every year, year after year. Examples trees, shrubs, tulips.

Plant Growth Requirements

1. Air (CO2 , O2)2. Light3. Temperature4. Soil (sandy, clay, crumbly)5. Water6. Minerals (Nitrogen, phosphorus, potassium)• Fertilizer is made of minerals that improve

the soil.

Chapter 21.3

• Diseases and insect pests can slow or stop plant growth. Diseases affect all plants.

• Bacteria- enter plants through the stomata or small cuts. Bacteria destroy plant cells when they invade cytoplasm. Example Blister Spots

• Viruses- can cause small yellow spots on leaves. Yellow spots darken and the tissue dies (Mosaic disease).

• Viruses can also cause tumors in leaves.

Mosaic Disease

• Fungi- disease caused by a fungus can spread rapidly examples Dutch elm disease, wheat rust, corn smut.

Wheat Rust

Dutch Elm Disease

Corn Smut Disease

• Insect Pests- can transfer diseases from one plant to another.

• Insects can also damage or even kill plants by eating too many leaves.

• Emerald Ash Borer• Tent Caterpillar• Gypsy moth

Emerald Ash Borer

Tent Caterpillars

Work Cited • “Sunflowers”. January 4, 2007.

http://northwestkansas.hdnews.net/graphics/photo%20gallery%20pics/SUNFLOWER%202.jpg• “Poinsettia”. January 4, 2007. http://www.movie-weblog.com/wp-content/uploads/poinsettia.jpg• “Rose”. January 4, 2007. http://www.aoc.nrao.edu/~mstephen/roywil.jpg• “Phototropism”. January 4, 2007.

http://intranet.cccmkc.edu.hk/~sbj-biology/AL%20BIO/Continuity%20of%20life%20growth%20and%20development/Growth%20and%20development_image/Tropism_image/Phototropism%20in%20mung%20bean%20seedling.jpg

• “Gravitropism”. January 4, 2007. http://botit.botany.wisc.edu/images/130/Tropisms/gravitropism/Gravitropism_MC.jpg

• “Thigmotropism” January 4, 2007. http://botit.botany.wisc.edu/images/130/Tropisms/Thigmotropism_MC_.low.jpg

• “Mosaic Disease”. January 8, 2007. http://plant-disease.ippc.orst.edu/plant_images/bluemosa.jpg

• “Wheat Rust Disease”. January 8, 2007. http://www.lsuagcenter.com/NR/rdonlyres/6DE10E67-5D37-4489-9D58-1928846CD2F4/9028/diseasewheatleafrust_w200.JPG

• “Dutch Elm Disease”. January 8, 2007. http://www.newsday.com/media/photo/2003-04/7291576.jpg• “Corn Smut Disease”. January 8, 2007.

http://www.apsnet.org/education/K-12PlantPathways/NewsViews/Images/Cornsmut.jpg• “Bacterial Disease”. January 8, 2007. http://www.kdcomm.net/~tomato/graphics/3bcanker.gif• “Emerald Ash Borer”. January 8, 2007. http://www.ppdl.purdue.edu/PPDL/images/eab-tracks.jpg• “Tent Caterpillars”. January 8, 2007. http://hflp.sdstate.edu/images/Tent%20caterpillar%20open

%20nest2.jpg