external plant parts
roots | stems | buds | leaves | flowers | fruit | seeds
home | introduction | plant life cycles | internal plant parts | external plant parts | plant growth & development
environmental factors affecting growth | plants in communities | plant hormones & growth regulators
How roots grow
During early development, a seedling absorbs nutrients and moisture from the soil around the sprouting seed. A band of fertilizer several inches to each side and slightly below newly planted seeds helps early growth of most row crops.
As a plant becomes well established, the quantity and distribution of its roots strongly influence its ability to absorb moisture and nutrients. For most plants, the majority of the absorbing (feeder) roots are located in the top 12 inches of soil. The soil environment in this region generally is best for root growth, with a good balance of fertility, moisture, and air spaces.
The following factors are important in root growth:
- Roots in water-saturated soil do not grow well and ultimately may die due to lack of oxygen.
- Roots penetrate much deeper in loose, well-drained soil than in heavy, poorly drained soil.
- A dense, compacted soil layer can restrict or terminate root growth.
- Container plants not only have a restricted area for root growth, but also are susceptible to cold damage because the limited amount of soil surrounding their roots may not provide adequate insulation.
- In addition to growing downward, roots grow laterally and often extend well beyond a plant's dripline. Keep this extensive root system in mind when disturbing the soil around existing trees and shrubs.
Roots as food
An enlarged root is the edible portion of several vegetable crops. Sweet potatoes are a swollen tuberous root; and carrots, parsnips, salsify, and radishes are elongated taproots.
