24.3 Plant Propagation and Agriculture

1. 24.3Plant Propagation and Agriculture Essential Question’s What is plant propagation?

2. Vegetative Reproduction • Vegetative reproduction – method a asexual reproduction that produces new plants from stems, plantlets, and underground stems • Plants grows by mitosis alone – no sexual reproduction • Enables plant to produce may offspring genetically identical to itself • Plants can reproduce very quickly since it does not involve pollination or seed formation

3. Plants can also reproduce by growing horizontal stems called stolons. • Strawberry plants are examples • Stolons produce roots when they touch the ground • Some plants like bamboo grow underground stems that allow plants to send up new shoots

4. Stolons of a Strawberry Plant

5. Plant Propagation • Propagation uses cuttings, grafting, or budding to make many identical copies of a plant or to produce offspring from seedless plants. • Plant hormones are often used to stimulate cuttings to grow • Grafting and budding are used to reproduce seedless plants and woody plants that do not produce strong root systems

6. Cont’d • A piece of stem is cut from the parent plant and attached to another plant • The cut piece is called the scion and the plant to which it is attached is called the stock • When wood stems are used as scions, the process is called grafting. • When buds are used as scions, the process is called budding.

7. Cont’d • Grafting works best when plants are dormant because wounds created can heal before new growth starts.

8. Figure 24-17

9. Agriculture • Agriculture is the systematic cultivation of plants • Developed about 10,000 to 12,000 years ago • Agriculture is the principal occupation of humans • Most people of world depend on a few crop plants such as wheat, rice, and corn for the bulk of their food supply. • About 80% of US cropland is used to grow just four crops: corn, wheat, soybeans, and hay.