what are different irrrigation systems available in india and Explai the formation of the cork
1. The important methods of irrigation available in India are:
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Dug wells and tube wells are used to supply water in crop fields. Tube wells are used to pump up the ground water and to release it in fields as per the requirement.
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Canals are man-made water channel systems, which are used to deliver adequate water to the fields. Canals are connected with water reservoirs, or rivers to distribute water in the fields.
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In a river lift system , river water is directly drawn from the river and is supplied to irrigate fields closer to the river. This is because in some regions, canals are irregular and insufficient because of low water levels in the river.
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T
anks are small, water storage reservoirs. These are helpful in delivering water in smaller areas.
Sprinkler system
This system is useful in watering land that is uneven and does not have sufficient supply of water. It consists of a series of perpendicular pipes with rotating nozzles on top. These pipes are joined to the main pipeline at regular intervals. Water flows through the pipes at a high pressure and gets sprinkled onto the land. This method is useful in irrigating sandy soil.
Drip system: In this system, water is supplied to plant roots drop by drop. Water is supplied to the plants directly with the aid of small pipes with holes. This is the best technique to water plants as it prevents wastage of water.
2.
During secondary growth, the outer cortical and the epidermis layer break down and are replaced by another meristematic tissue called the cork cambium.
Cork cambium or phellogen leads to the formation of cells on both sides:
- Outer cells − Differentiate into the cork (Phellem)
- Inner cells − Differentiate into the secondary cortex (Phelloderm)
Phellogen + Phellem + Phelloderm = Periderm
Phellogen exerts pressure on its peripheral layers, and due to this, these layers die.
Cork has suberin deposits on the cell wall. This makes it impervious to water and check the loss of water from the general surface of stem.