Study the Ability of Plants to Reproduce Asexually by Vegetative Propagation
There are two basic types of reproduction of living organisms. One type, sexual reproduction, requires the union of male and female sex cells, or gametes (sperm and eggs) in the formation of a new organism.
In this project, you will study the second type of reproduction, asexual reproduction, where there is no union of sex cells. The ability of plants to reproduce asexually by vegetative propagation will be studied. You will also discover some methods and special plant organs by which plants can asexually reproduce.
Purpose: To produce a new plant by fragmentation.
- 2 1-quart (1-liter) jars
- Distilled water
- Geranium plant
- Fill the jars three-fourths full with distilled water.
- Use the scissors to cut four healthy stems with healthy leaves from the geranium plant.
- Place two stems, cut ends down, into each jar of distilled water (see A in Figure 8.1).
- Place the jars where they will receive direct sunlight.
- Observe the cut ends of the stems daily for two to three weeks.
- Transfer the cuttings to flowerpots filled with potting soil for further growth.
- Keep the plants watered and observe their growth for several months.
In 10 to 14 days, small roots can be seen growing from the ends of the stems (see B in Figure 8.1). These roots continue to grow. The potted stems mature into plants resembling the original (parent) plant.
Asexual reproduction is a method of reproducing a new organism from one parent One type of asexual reproduction is vegetative propagation (the production of a new organism from a nonsexual part of one parent). In multicelled organisms such as plants, broken pieces from the plants can develop into new plants. Special roots called adventitious roots develop directly from stems or leaves instead of from the normal root system.
Fragmentation is an example of vegetative asexual reproduction. In this process, a new plant grows from a part broken from a parent plant The cutting taken from the geranium plant grows into a plant identical to the parent plant.
Asexual reproduction has several advantages. First, this method can be used to grow identical plants faster and more successfully than a method that relies on seed germination. Second, seedless fruit can be produced and propagated via vegetative reproduction. Third, asexual reproduction preserves the status quo in that the offspring are always exactly like the parent.
Try New Approaches:
- Do leaves affect the ability of a stem to reproduce by fragmentation? Repeat the experiment two times, first using stems with no leaves, and then using stems with a greater number of leaves than the stems used in the original experiment.
- Does the type of plant affect its ability to reproduce by fragmentation? Repeat the original experiment using stems from different types of houseplants. Discuss the project with a professional at a nursery and secure sample cuttings from different types of plants.
- For vegetative propagation to occur, adventitious roots must form. The development of these special roots depends on a hormone called auxin. Can the hastening of the production of adventitious roots be achieved by pretreating the cuttings with a synthetic auxin solution? Repeat the original experiment using synthetic auxin purchased from a nursery. Follow the procedure on the product's packaging for treating the cuttings.