Introduction
Water is the most plentiful component of all physiologically active plant cells. For example, leaves have water content within a range of 55–85% of their fresh weight. Other relatively moist parts of plants contain nearly the same proportion of water, and even large non-living tissues such as wood may be 30–60% water on a fresh-weight basis. The smallest content of water in living parts of plants occur mostly in inactive structures like the mature seeds and spores.
A unit system is constituted by the large amount of the water in any plant. The condition of this water is not static. It is part of a hydrodynamic system, which in terrestrial plants involves adsorption of water from the soil, its translocation throughout the plant, and its loss to the environment specifically in the process known as transpiration.
Imbibition is a special type of transport of water to the plants when water is absorbed by colloids which are solid particles and causes them to enormously increase in volume. The basic examples of imbibition are absorption of water by seeds and dry wood.
Plant Water Relations
Even though water is the most plentiful molecule on the Earth’s surface, water availability is the factor that strongly restricts production of terrestrial plants on a global scale. Low availability of water binds the productivity of many natural ecosystems, particularly in dry climates. Regions where rainfall is rich and evenly distributed over the growing season, such as in the wet tropics, have lush vegetation.
Where summer droughts are frequent, forests are replaced by grasslands. Further reduction in rainfall results in semi deserts which have scattered shrubs and then they finally become deserts. Even the effects of temperature are partly applied through water relations because rates of evaporation and transpiration are inter-related with temperature.
Thus, for better understanding of natural trends of productivity or to increase productivity of agriculture or forestry, it is important to understand the controls over plant water relations and the adversity of plant growth in an inadequate water supply.
Imbibition In Plants
Imbibition is defined as a process of adsorption of water or any other liquid by the solid particles of a substance without forming a solution. It is a unique type of diffusion which takes place when water is absorbed by colloids causing an increase in volume.
In other words the absorption of water by hydrophilic colloids is called Imbibition. Solid substances that take part in imbibition are called imbibants and the liquid which is imbibed is known as imbibate. Imbibitional Pressure is the pressure created that increases the volume of the imbibant.
Characteristics Of Imbibition In Plants
The process of imbibition in plants possess certain characteristics which are as follows:
Adsorption: Imbibant holds water or the imbibate due to the force of attraction between the imbibed and the imbibant.
Water Potential: Imbibing has an adverse water potential which is called matric potential. Water has however the highest maximum water potential where maximum refers to zero.
Water Potential Gradient: When a dry imbibant which has a high negative water potential comes in interaction with water which has maximum water potential, a sharp gradient of water potential is formed and water diffuses fast from its higher potential into the imbibant.
Heat of Wetting: Heat energy is released during imbibition. This is called the heat of wetting.
Increase in Volume: During imbibition, there is an increase in the volume of the imbibant. The swelling of soaked seeds and the swelling of wooden frames during the rainy season are common examples of imbibition.
Conditions Required For Imbibition In Plants
For the process of imbibition, certain conditions are needed to be followed which includes that a water potential gradient should arise between the imbibant substance and the liquid that is being imbibed. For occurrence of imbibition, there should be some forces of attraction between imbibants and imbibed liquid.
Adsorption is the property of colloids, and therefore the materials with a high proportion of colloids are good imbibants, and for this purpose, the wood is considered to be a good imbibants because it contains protein, cellulose and starch as colloidal substances.
Factors Affecting Imbibition In Plants
The factors affecting imbibition are as follows:
Texture of imbibing: More imbibition is observed in imbibants that are loose and not dense. Colloidal materials imbibe easily and this is why wood is a very good imbibant as it contains lignin, cellulose, etc.
Temperature: The temperature is directly proportional to imbibition. With the increase in temperature, the thickness of liquid generally decreases, and thereby imbibition, which is inversely related to thickness, increases.
Pressure: Imbibition is adversely related to the rise in pressure. With a rise in pressure, the imbibition decreases. If the imbibing substance is kept in a restricted place, there is an increase in the volume due to the pressure developed.
pH of the medium: Depending upon the charge of the imbibant, the imbibition either increases or decreases.
Role Of Imbibition In Plants
- The initial step in the absorption of water by the roots and cells is imbibition,
- Imbibition of water by cell walls provides moisture to the cells, and
- Imbibition pressure helps in germination of seeds, ascent of sap in plants, etc.
Conclusion
We can conclude from the article that imbibition is one of the most important physiological phenomena in plants. This process considers the imbibate and imbibant. This is a surface phenomenon and does not process the formation of a solution. This is an important process, as seeds swell up during germination because of the process of imbibition. For better understanding of the topic, the characteristics of imbibition is also discussed. The factors affecting imbibition, the role of imbibition in plants have also been elaborated for better knowledge.