Describe the function of root system
Answers
The functions of the plant root system include:
1. Anchorage and support. The plant root system anchors the plant body to the soil and provides physical support. Redwood trees (a gymnosperm) about 100 meters tall have stood erect for thousand years only because millions of individual fibrous roots dig into the ground, even though the depth of penetration is only up to about 5 meters. In general, however, taproot system provides more effective anchorage such that they are more resistant to toppling during storms.
2. Absorption and conduction. The plant root system absorbs water, oxygen and nutrients from the soil in mineral solution, mainly through the root hairs. They are capable of absorbing inorganic nutrients in solution even against concentration gradient. From the root, these are moved upward. Plants with a fibrous root system are more efficient in absorption from shallow sources.
In the desert plants called phreatophytes like the mesquite, the roots seek permanent underground water reserves. These plants are water indicators and knowledge of such plants has been put to use by digging wells where they grow (Went and The Editors of Life 1963).
3. Storage. The root serves as storage organ for water and carbohydrates as in the modified, swollen roots of carrot, sweet potato (camote) and yam bean (sinkamas). Fibrous roots generally store less starch than taproots. Some roots are capable of storing large amounts of water; the taproots of some desert plants store more than 70 kg of water (Moore et al. 2003). (Click to read Starchy Root Crops, Tuber Crops and Corm Crops)
4. Photosynthesis. Some roots are capable of performing photosynthesis, as in the epiphytic orchids and aerial roots of mangrove trees.
5. Aeration. Plants that grow in stagnant water or other watery places have modified roots called pneumatophores to which oxygen from the air diffuses.
6. Movement. In many bulb- and corm-forming plants, contractile roots pull the plant downward into the soil where the environment is more stable.
7. Reproduction. The plant root system also serves as a natural means of perpetuating a species. In mature agoho or horsetail tree (Casuarina equisetifolia) and certain plants, clonal seedlings or offshoots are commonly seen growing profusely around the trunk from horizontally growing roots. Likewise, new plants emerge from left-over tuberous roots after harvest in fields grown to sweet potato (Ipomaea batatas) and yam bean (Pachyrhizus erosus). As a rule, plants with a fibrous root system are easier to transplant than those with tap roots. (click here for more examples of plants that can be propagated by root cuttings).