How Water Scarcity Affects Plant Growth and Physiology
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 Effects of Water Scarcity on Plants and Drought Stress Response
1. What are the effects of water scarcity on plants?
Water scarcity causes reduced growth, wilting, decreased photosynthesis, and in severe cases, plant death. When plants experience water stress, the following effects occur:
- Stomatal closure, which limits carbon dioxide intake
- Reduced photosynthesis and food production
- Loss of turgor pressure, leading to wilting
- Inhibited cell division and elongation
- Premature leaf drop and reduced yield
Prolonged water scarcity can severely affect crop productivity and ecosystem balance.
2. How does water scarcity affect photosynthesis in plants?
Water scarcity reduces photosynthesis by causing stomata to close, limiting carbon dioxide entry into the leaf. When water is insufficient:
- Stomatal closure decreases CO₂ availability
- The light-dependent reactions slow due to limited water as a raw material
- Sugar production declines
Since water is a key reactant in photosynthesis, its shortage directly reduces energy production and plant growth.
3. Why do plants wilt during water scarcity?
Plants wilt during water scarcity because they lose turgor pressure in their cells. Turgor pressure is maintained by water inside the vacuole, which keeps cells firm. When water availability decreases:
- Cells lose water through transpiration
- The vacuole shrinks
- Cells become flaccid instead of rigid
This loss of rigidity causes leaves and stems to droop, resulting in visible wilting.
4. What is water stress in plants?
Water stress in plants is a condition where water availability is insufficient to meet the plant’s physiological needs. It occurs when:
- Soil moisture is low
- Transpiration exceeds water absorption
- Roots cannot supply adequate water to shoots
Water stress disrupts metabolism, reduces growth, and may trigger protective responses such as stomatal closure and root elongation.
5. How does water scarcity affect plant growth and development?
Water scarcity slows plant growth by reducing cell division and cell elongation. Water is essential for:
- Maintaining turgidity for cell expansion
- Transporting nutrients through the xylem
- Enabling metabolic reactions
As a result, drought-stressed plants show stunted growth, smaller leaves, fewer flowers, and reduced fruit production.
6. What happens to stomata during water scarcity?
During water scarcity, stomata close to reduce water loss through transpiration. This response is regulated by the hormone abscisic acid (ABA), which signals guard cells to close the pore. The effects include:
- Reduced water loss
- Limited carbon dioxide intake
- Lower photosynthetic rate
Although protective, prolonged stomatal closure reduces plant productivity.
7. How does water scarcity affect nutrient uptake in plants?
Water scarcity reduces nutrient uptake because minerals are absorbed in dissolved form through the soil solution. When soil moisture is low:
- Mineral ions move slowly toward roots
- Root absorption efficiency declines
- Transport through the xylem decreases
This can lead to nutrient deficiencies, even if minerals are present in the soil.
8. What are the long-term effects of drought on plants?
Long-term drought can cause permanent damage to plant tissues and reduce survival rates. Extended water scarcity may result in:
- Death of meristematic tissues
- Reduced reproductive success
- Increased susceptibility to pests and diseases
- Altered root-to-shoot ratio
In crops, prolonged drought significantly lowers yield and quality.
9. How do plants adapt to water scarcity?
Plants adapt to water scarcity through structural and physiological modifications that conserve water. Common adaptations include:
- Deep or extensive root systems
- Reduced leaf surface area or spines
- Thick waxy cuticle
- CAM or C4 photosynthesis pathways
These adaptations improve water-use efficiency and enhance drought tolerance.
10. Can water scarcity cause plant death?
Yes, severe and prolonged water scarcity can lead to irreversible damage and plant death. When dehydration becomes extreme:
- Photosynthesis stops completely
- Cells lose structural integrity
- Vascular tissues fail to transport water
If rehydration does not occur in time, essential metabolic processes cease, resulting in permanent tissue damage and death.
