How does a plant respond to decreased levels of water?

Water is important to plants as it helps in the various biochemical processes that take place within the plant cells. Most plants require a continuous supply of water to maintain their metabolic activities. However, when there is a decrease or shortage of water supply, plants have developed an array of responses to help them survive even under these unfavorable conditions.

Changes in stomatal behavior

Plants have specialized cells known as stomata, which are responsible for regulating water use and gas exchange. Stomata regulate the flow of water vapor and carbon dioxide into and out of the plant cells. During water scarcity, the stomata close to minimize water loss through transpiration. Closed stomata also help to conserve the plant's energy and reduce its metabolic activities, allowing it to survive for longer periods with less water.

Production of Abscisic Acid

Abscisic acid (ABA) is a hormone produced by plants in response to water stress. The hormone signals the plant to reduce its water use to prevent further water loss. ABA induces various cellular processes such as reducing the opening of stomata, promoting the synthesis of protective proteins, and stimulating root growth, which is useful for optimizing water uptake from the soil.

Root morphology modification

Plants can adapt their root systems in response to reduced water availability. The roots of some plants become longer and thinner, allowing them to explore greater soil depths to access available water resources. Other plants may develop a profusion of shorter, thicker roots near the soil surface, enabling them to collect water more efficiently from the topsoil. Some plant species may also develop root hairs, which increase the overall surface area of the roots, allowing them to absorb water at a higher rate from the surrounding soil.

Reduced growth rate and dormancy

Plants exposed to extended drought conditions may reduce their growth rate or become dormant to conserve their energy and reduce metabolic activities. Dormancy is a crucial adaptive response to help plants cope with prolonged drought periods. During the dormancy phase, plants conserve their energy by reducing leaf production, shedding unnecessary leaves, and decreasing their resource requirements. The reduction in resource requirements allows the plant to minimize the amount of water needed for survival during periods of water scarcity.

Conclusion

In conclusion, plants have evolved several responses to cope with decreased levels of water. The adaptive responses in plants serve to preserve water and energy, optimize water use, and increase the plant's tolerance to drought stress. Understanding these responses to drought stress is critical in developing crop species that can withstand water scarcity and improve food security in arid and semi-arid regions of the world.