Major Reasons for Water Shortage and Its Consequences on Plant Life
Around 96.5 per cent of all the earth's water is stored in oceans. The water in the oceans is saline in nature and hence is not drinkable. The remaining 3% are freshwater, with less salt, but they are mostly trapped in the vast glaciers and ice sheets of Greenland. Lakes, rivers, soils, and the atmosphere partly hold fractions of freshwater.
Freshwater reservoirs on land replenished by the hydrological cycle are extremely important for people, animals, and plants. These water bodies provide water not only to animals and people but also replenish groundwater and encourage vegetation.
Rain falling on the earth is retained as soil moisture, essential for the earth's vegetation. Rainwater percolates through soil layers and pores to reach the underground water bed, which are freshwater aquifers. This forms the groundwater, which is a source of drinking water for us.
Role of Water in Plants
Water plays an important role in the life functioning of the Plant. Plants draw water from the soil through their roots, which contain essential nutrients for the plant’s growth. Water pressure (turgidity) helps maintain the cell structure of plants. Plants need water to make their foods through photosynthesis.
Plants exchange water for maintaining temperature. The water absorbed through roots flows through the plants due to osmotic pressure circulating nutrients, and removing waste. The leaf stomata open up to release the water back into the environment.
Effect of Water Scarcity on Plants
Drying up the soil leading to water scarcity, can disrupt this essential process. Extreme temperatures cause heat stroke in plants. The common effect of water stress in plants is wilting of leaves. The plant appears to limp and begins to collapse as the plant cell loses the turgor pressure.
Lack of water hampers photosynthesis and can even completely halt the process. The leaves become yellow at this point.
Water stress can affect plant respiration, by which plants break down nutrients to generate energy. Lack of water reduces photosynthesis which in turn affects respiration.
Water Scarcity in plants can eventually kill them by influencing all the above processes. Few desert plants have evolved to survive in dry areas. They have penetrating roots to search deep under the ground for water. Their leaves are modified to reduce water loss by adopting a thorn-like structure.
Reasons for Water Scarcity
The causes of water scarcity are mainly human actions along with some environmental factors. Some common reasons for water scarcity are:
Population Increase
Human activities have deeply harmed the water ecosystem of the earth, as large human habitats are reporting water crises. Population increase has pressurised the already scarce water resources. Dense urban habitat overconsumes the groundwater in the region for drinking purposes.
Urbanisation
Concretisation of cities prevents rainwater from percolating through the soil and replenishing the groundwater reservoir. Most of the rainwater runs off and gets polluted. Industrial effluents and sewage also pollute the water bodies rendering them unusable, which then goes on to degrade the vegetation around them.
Climatic Change
Increases in global temperature have shifted the weather pattern. High-temperature results in greater evaporation of water from the oceans leading to abnormal rainfall. Sometimes there is sudden heavy rain followed by long dry spells leading to drought.
Environmental Degradation of Natural Water Sources
Degrading or destroying the natural freshwater reservoir like ponds, lakes, and wetlands due to urbanisation adds to the water woes. They are natural water retainers and purifiers. These reservoirs are a lifeline for the local vegetation.
Overuse for Irrigation
Overuse of groundwater due to irrigation can run the underground water bed dry, resulting in desertification and subsequent water scarcity.
Remedies
The condition of water resources has deteriorated due to environmental degradation, human irresponsibility, and climate change. Water scarcity is also a result of poor social planning and underdevelopment. The mitigation effort has to address these problems. We should adopt practices to manage the water available to us better.
Few ways to improve water scarcity-
Water Recycling and Reusing
Better wastewater management facilities should be built to reuse the wastewater from households for other purposes, such as gardening.
Treatment of Water
Sewage and industrial effluents should be treated before releasing them into rivers or lakes to protect the surrounding vegetation.
Conservation of Natural Water Reservoirs
Natural water bodies need to be preserved and maintained across our landscape. We should avoid dumping waste into these water bodies and provide proper legal and social protection to these reservoirs to save them from encroachment and construction.
Adapting Traditional and Indigenous Water Conservation Methods
Interesting Facts
30% of land in India has undergone desertification due to the depletion of wetlands, deforestation, and over-cultivation.
Hygrometer and soil moisture sensors are used to measure the volumetric water content in the cell.
Key Features
71% of the earth’s surface is covered by water.
Only a small fraction, about 3%, is freshwater which is essential for plants, animals, and humans.
Generally, water scarcity is caused due to depletion of natural sources, which leads to the degradation of vegetation.
Plants need water to maintain basic life functions.
Water scarcity disrupts the basic processes in plants and causes heat shock.
FAQs on How Water Scarcity Affects Plants: Key Impacts and Adaptations
1. What are the immediate effects on a plant when water becomes scarce?
When water is scarce, the most immediate effect on a plant is the loss of turgor pressure. Plant cells lose water, causing them to become flaccid. This results in the drooping or wilting of leaves and stems, which is the plant's first visible response to water stress. This wilting helps reduce the surface area exposed to sunlight, thereby conserving the remaining water.
2. What are the primary visible signs that a plant is suffering from a lack of water?
The primary visible signs of water scarcity in plants are:
Wilting: Leaves and young stems droop and appear limp.
Leaf Discoloration: Leaves may turn yellow (chlorosis) or brown, starting from the edges, and eventually dry out.
Leaf Drop: The plant may shed older leaves to reduce water loss through transpiration.
Stunted Growth: Lack of water inhibits cell division and expansion, leading to poor growth, smaller leaves, and shorter stems.
3. How does water scarcity disrupt the process of photosynthesis in plants?
Water scarcity severely disrupts photosynthesis, the process plants use to create food. To conserve water, plants close the tiny pores on their leaves called stomata. While this reduces water loss, it also prevents the intake of carbon dioxide (CO2) from the atmosphere. Since CO2 is a key ingredient for photosynthesis, its limited availability slows down or even stops the plant's ability to produce energy, hindering its growth and survival.
4. Besides wilting, what are some internal, less obvious effects of water stress on a plant?
Internally, water stress triggers several less obvious but critical changes. The transport of nutrients from the soil via the xylem is reduced because water acts as the transport medium. The plant may also start producing stress hormones like abscisic acid (ABA), which signals the stomata to close. This can lead to a buildup of reactive oxygen species (ROS) inside the cells, causing oxidative damage to cellular structures if the stress is prolonged.
5. How does a lack of water affect a plant's growth and ability to flower or produce fruit?
A lack of water directly impacts a plant's growth and reproductive capabilities. Cell enlargement, which is necessary for the growth of roots, stems, and leaves, is highly dependent on water pressure. Without sufficient water, this process halts, resulting in stunted growth. Furthermore, a water-stressed plant will prioritise survival over reproduction, often leading to a failure to produce flowers, premature dropping of existing flowers or fruits, or the development of smaller, lower-quality fruits and seeds.
6. Why are some plants better at surviving in dry conditions than others?
Plants that thrive in dry conditions, known as xerophytes, have developed special adaptations to combat water scarcity. These are not found in plants from water-rich environments. For example, cacti have replaced leaves with spines to reduce water loss and have thick, waxy stems to store water. Other plants may have deep root systems to access water far below the surface, or silvery hairs on their leaves to reflect sunlight and keep cool. These evolutionary traits are the key reason for their superior survival.
7. What are some common examples of plant adaptations for surviving water scarcity?
Plants have evolved a variety of adaptations to survive in arid environments. Key examples include:
Succulence: Storing water in thick, fleshy leaves or stems (e.g., Aloe Vera, Cactus).
Reduced Leaves: Having small, needle-like leaves or spines to minimise the surface area for transpiration (e.g., Pine trees, Cacti).
Deep Root Systems: Growing extensive or very deep roots to reach underground water sources (e.g., Mesquite tree).
Waxy Cuticle: A thick, waxy coating on leaves to prevent moisture from evaporating (e.g., Holly).
Dormancy: Entering a dormant state during dry periods and reviving when water is available.
8. How does long-term drought differ from a short-term water shortage in its impact on plants?
A short-term water shortage causes temporary, often reversible effects like wilting. If water is provided, the plant can regain its turgor pressure and recover fully. In contrast, a long-term drought causes chronic, often irreversible damage. The plant experiences prolonged stunted growth, permanent damage to photosynthetic machinery, death of roots and branches, and extreme vulnerability to diseases and pests. Ultimately, a long-term drought can lead to the death of the plant, whereas a short-term shortage is a survivable stress event.
