What is a yield? Why do we need to increase it? • NOTES: A yield is how much of a crop is produced. • We need to increase yield because our populations keep growing, so we need to get more plants out of the same amount of land.
What do we do to increase Yield? • Spend a few minutes to think of some ways that we can increase yield. • Notes: Ways to increase yield. • Improve the soil quality • Provide the plants with ideal growing conditions • Modify the plants so that they grow better in the same environment • Change the environment completely • Greenhouses • Hydroponics
Modifying plants • There are two main ways that we modify the plants themselves in order to increase yield or a better plant • These two ways are Selective breeding, and Genetically modifying the plants.
Selective breeding • Notes: Selective breeding is when humans choose which plants will produce the best offspring and breed those plants in order to get characteristics that we want. • Can you think of any plants that have been selectively bread?
Genetically modified organisms or GMO’s • Notes: A GMO is a plant or animal that scientists have modified their genes in order to give the organism a characteristic that it didn’t have before. • For example We can take genes out of a jelly fish and put them into a flower and make the flower glow in the dark.
Creating new plants has it’s problems • When we create new plants we also create new problems. • Sometimes that plants that we create are so good that they begin to take over, and don’t leave any room for other plants. • Sometimes these plants may have unforeseen characteristics like being poisonous.
Terms to Know (write this in notes) • Species: A species is a group of organisms with very similar characteristics that can reproduce. • Variety: A variety is a subset of species. For example different types of apples. • Trait: A trait is a characteristic, like I have brown hair is a trait.
Ways that we modify the environment • There are a number of ways that we modify the environment to increase yields. We are going to focus on 2 types • Greenhouses • Hydroponics
Greenhouse • What is a greenhouse? • Notes: A greenhouse is a manmade structure that holds in sunlight and water so that plants will grow faster and not be damaged by weather. • How do they help? • Because the greenhouse keeps the climate constant and provides the plants with very good opportunities to grow, the plants in greenhouses often grow larger and produce more fruit.
Hydroponics • What is Hydroponics? • Notes: Hydroponics is growing plants with no soil, the plants grow in a liquid medium that is full of nutrients and everything else that the plants need except sunlight which is provided by UV lights. • Like a greenhouse hydroponics gives the plants exactly what they need in the right amounts so that the plants grow larger and produce more fruit.
Section 4.3: Controlling weeds and pests • Herbicides and Pesticides, what are they? • Notes: Herbicides are chemicals that kill plants. Herbicides can kill only specific types of plants, (weedex), or all plants (roundup) • Pesticides: Are substances that kill insects or other unwanted animals.
Pro’s and Con’s to Herbicides and Pesticides • Notes: By killing off certain types of plants and animals we allow for other plants and animals to prosper. This means that the other plants will grow faster and larger because they don’t have any competition. • However: The plants and animals that we kill were also involved in the food chains. This means that we have removed a link. This may cause major problems to other parts of the food chain.
Take a few minutes to think about what effects removing a link from the food Chain might Cause. Notes: Unintended Consequence: Something that happens that you didn’t predict. For example: You introduced lady bugs to eat aphids and protect your crop. This caused all of the bats in the area to die because the bats eat aphids.
Alternatives to pesticides and Herbicides • Notes: Biological Control: A biological control is introducing a natural predator or competitor to help keep a group of plants or insects under control. • Can you think of any examples of how this might work?
Definitions to Know • Environmental Management: Balancing the needs of humans with the needs of the environment. • Monoculture: Growing just one variety of plant. For example a field of all wheat. • Biodiversity: The number of different species in a specific area. • Sustainable: Something that can keep going on forever. A sustainable harvest is a harvest that could occur every year for ever.