As living things, humans need water for their survival likewise plants also need water to sustain themselves. What purpose does water serve in the plant body? 90% of the plant body constitutes water. Starting from germination to the fruiting stage water is inevitable for plants. Let’s dig deeper into the science of plant-water relations.
How Water Is Absorbed
Plants have distinct parts and each part has a unique function. It is the roots that carry water and minerals from the soil. Water absorption is mainly through the plant’s roots. Leaves can also absorb water to a certain extent. Nowadays foliar spraying is also widely used for faster absorption.
Functions of Water in Plants
Water has several responsibilities in plants. They transport raw materials for food preparation and also transport prepared food to growing parts. Water also helps plants to maintain their posture and regulate temperature as needed. Let’s look into the details.
Seed Germination
Generating a new plant via plant seeds is the process of germination. Water is essential for this process as it helps the plant seeds to break their seed coat. Water softens the seed coat through the process of imbibition. And again the function of water is not limited to this. During seed germination, the food stored in the endosperm is converted to a form that can be utilized by the growing embryo. This process requires hydrolytic enzymes. Hydrolytic enzymes require water for their activation. Finally, water transports the soluble food to growing parts.
Nutrient Transport
Plant growth demands many essential nutrients. These nutrients reach the plant body with the help of roots. Plants can’t absorb nutrients directly. They can be only absorbed when they are dissolved in water. The plant vascular system transports the absorbed water and nutrients from the soil to leaves for photosynthesis. This process is termed mineral nutrition.
There are two primary vascular tissues. They are the xylem and phloem. Xylem conducts water and nutrients upwards whereas phloem conducts food downwards from leaves.
Maintain Shape and Structure
Water is transported from plant cell to cell through osmosis. The osmotic water flow creates a pressure called turgor pressure which gives the plant mechanical support and keeps the stomata open. Stomata are pores that aid in gaseous exchange. Guard cells surrounding the stomata help in their opening and closure. The turgor pressure retains the shape and structure of plants.
Photosynthesis
The process of generating sugar and oxygen by utilizing sunlight, carbon dioxide, and water is photosynthesis. Sunlight is directly absorbed whereas carbon dioxide is obtained through stomata.
Photosynthesis takes place inside the chloroplast present in plant leaves. Chloroplast contains a pigment-protein called chlorophyll which absorbs light energy. The intake of carbon dioxide and the release of oxygen happens during photosynthesis. Carbon dioxide won’t come inside if the stomata are not properly open. To keep stomata open there shouldn’t be any water insufficiency.
Transpiration
Water loss through the stomata is transpiration. When the temperature rises water evaporates through the stomata to cool down the plant just the way humans sweat. The whole process of transpiration is for the temperature control of plants. When water uptake through roots decreases the rate of transpiration increases and there is a chance for plants to wilt.
Preserve Soil Ecosystem
Water’s importance in preserving the soil ecosystem is remarkable. The soil consists of many microorganisms which contribute to plant growth. The microbes can survive only when there is water present in the soil. Plants provide food for these microbes. In return, they keep the plant away from stress. Microbes also enrich soil nutrients.
Do Plants Feel Thirst?
The answer is yes. Plants also feel thirsty. So far the discussion was about plants need water. Water being the main component of growth, can’t afford to have mere negligence. Plants show different signs to indicate it needs water.
Wilting Leaves
Sometimes we see plants wilt and die. Inadequate irrigation would be the reason most probably. The excess water loss decreases the turgor pressure inside the plant’s cells. As a result, plants can’t keep their shape intact.
Browning of Leaves
Another indication by plants. Leaves can curl and turn brown when water is insufficient.
Stunted Growth
Water insufficiency can deteriorate growth. Sometimes we see certain plants show no change over time, they stay the same for a longer time. This can be due to lack of watering.
Is It Okay to Water Excessively?
Plants are needy of water. But before watering it is necessary to know in what quantity water should be given. Too much water can harm plants just the way too little water can. Regular inspections of the garden can make sure plants are getting enough water as it demands. Plants also give indications of excess watering.
Wet Soil
Plants absorb water through roots which are spread across the soil. There are air pockets inside the soil. Excess water can make these air pockets disappear and thus the plant will not get enough oxygen.
Yellowing of Leaves
When a plant absorbs more water than it could use leaves start to turn yellow and gradually brown.
Water Pressure Rises
Excess water in plants can raise the water pressure inside the plant cells. The increased pressure can damage the cell and cell wall. Eventually, plant cells will burst and these can be observed as blisters.
Best Practice for Watering Plants
The way you water houseplants determine whether you are a gardening expert or not. Houseplants are of different types. Outdoor plants, indoor plants, and container plants. Each of them has a discrete water requirement.
Outdoor Plants
Water should be given to plants to thrive in hot climates. In the case of garden plants water can be poured directly into the ground. Water travels up through the roots. First, water deeply and less frequently, thus roots can go deep in the soil in search of water thus promoting root development. Second, water only when the soil feels dry. Lastly, avoid watering foliage as it may lead to fungus and mold.
Indoor Plants
Indoor plants should be kept in a bright light area as they receive comparatively less light. Water them accordingly. First, use your finger to check whether the soil is moist one or two inches deep. If it’s moist don’t water further.
Container Plants
Choose a container with drainage holes. Prepare potting mix in such a manner so that it can hold moisture for a long time. Add substances like coco peat and sand for moisture retention and good drainage. Water daily. In hot summer water twice a day.
Plants can also be grown in water-based nutrient solutions. This technique is known as hydroponics. Hydroponic plants ensure more yield than plants grown in a soil medium.
Types of Water to Use
The type of water you choose for your plants can also affect their growth. The softened water obtained by adding water softeners to tap water can hurt your plants. The salts present in these softeners can kill the plant.
Distilled water can be used on plants as they are the product of vaporization.
Watering in Different Seasons
In summer as the temperature is too high and the transpiration rate increases it is ideal to water plants twice a day.
During winter plants receive less light energy and enter dormancy. Very little water is recommended at that time.
Plant’s growth spurt during spring as a result demand for water is high.
Rainwater
Rainwater is rich in minerals and is free from chemicals. Unlike tap water, you don’t have to be cautious about rainwater. The nitrate present in rainwater makes plants look lusher as nitrogen is one of the essential nutrients for plants. Most plants require a pH of 5.5-6.5. The pH of rainwater is 7 which makes it the best choice for plants.
Some places receive less annual rainfall so depending on rainwater is not a wise choice. In places with high annual rainfall, rainwater can be collected and made use of it.
Final Thoughts
Now it is clear that Water plays a crucial role in the plant life cycle. Water should be given accurately. Water is needed from sprouting to fruiting. Chemical reactions like photosynthesis are incomplete without water. Plants withstand temperature variations with the help of water. Besides, water also contributes to the symbiotic relationship between plants and microbes in the soil thus improving the overall ecological functioning.
FAQs
Why do plants grow better with water?
Water is unavoidable for a plant. Water helps the plant to maintain its shape and structure, prepare its food and thrive in harsh environmental conditions. When a plant is deficient in water, the water pressure inside the plant decreases and the plant may wilt and die.
Why do plants survive without water?
No plant can survive without water. Even succulents require a limited amount of water.
What are the functions water plays in plants?
Sprouting of seeds – It softens the seed coat and activates enzymes in the cotyledons to break the food into energy. This energy is also transported by water to the growing parts.
Mechanical support – It creates a turgor pressure inside the cells which keeps the plant sturdy.
Photosynthesis – The process of generating glucose from light in the presence of carbon dioxide and water.
Nutrient transport – Nutrients are absorbed by the roots when they are dissolved in water.
Last Updated on by kalidaspandian
