Root Pressure and Guttation

Introduction

Plants transport all the nutrients and water upwards and equally distribute to their parts by using a complex array of biological processes called root pressure and guttation. Even the tallest trees have gravity-defying properties as the sucking of nutrients happens from the deepest depths of the soil and moves in the upward direction. These are the most intriguing processes in the plant life cycle that helps plants to maintain either a higher or lower pressure based on the surroundings.

What is Root Pressure?

The pressure applied in the xylem when water and other ions are transmitted from the soil to the vascular tissues is called root pressure.

Functioning of Roots

The root system of a plant can change its pressure to either:

1. Help water and nutrients rise throughout the plant.
2. Push water and nutrients out of the plant.

Before jumping on the concept of root pressure, it is highly significant to know a few basic terms interconnected with it to better understand the process.

Osmosis

Osmosis is the basic and primary source of root pressure. When the concentration outside the root system of the plant’s water is greater than inside the root system, it moves over the root membranes and inside the plant’s water and nutrient transportation system.

Xylem and Phloem

They are the circulatory system of plants, and each has a specialised function:-

• Xylem treats the transporting water (necessary for photosynthesis, among other things)
• Phloem is used to transport nutrients like sugars and other organic compounds

Transpirational Pull

The transpirational pull is the process that is most responsible for shuttling water up a plant’s xylem vessels. The idea is that transpiration, the evaporation of water from the surface cells of leaves, causes a pressure differential that favours the upward movement of water through the xylem of a plant. In simpler terms, water is evaporated through the leaves of plants, which even causes a ‘sucking’ action of water up through the plant. It is transpirational pull, among other functions, that causes most of the upward movement of water in plants, with hypotheses claiming that root pressure lends a helping hand.

Experiment to find out Root Pressure in Plants

In order to know that root pressure exists, take a small herbaceous plant when there is a lot of atmospheric moisture present.

• Using a sharp blade, cut the stem of the plant in a horizontal manner
• After cutting it, you will notice droplets coming out of the plant stem. This is what is called positive root pressure
• Now, insert a tube made of rubber into the stem. This is to identify and measure the exudation rate

Root pressure is also noticeable early in the morning or at night times. During this time, droplets of water get collected surrounding the veins and leaves of plants.

What is Guttation?

Guttation is a process that usually occurs due to a mixture of high root pressure (which may be caused by different factors) and a low evaporation rate/too high humidity. This often happens just after sunrise when the plant becomes active, and the humidity is also quite high. One way that plants can equalise the amount of water they take in is by a process called guttation. This process takes place in plants that have vascular systems, like grass, wheat, barley, tomatoes, etc., and other small plants. Since guttation relies on pressure, it can not occur in large plants, such as trees, because the pressure required to force the water out is too large. It can also happen during night times, as the soil is wet or moist. However, if the root has too much water, they get squeezed out when root pressure is applied. This is what is called xylem sap (includes enzymes, minerals and other chemicals) and these watery fluids line up at the edges of the leaves looking like dew drops.

Effects of Guttation

Guttation is usually harmless if the water gets dropped out of the leaf. If that’s not the case, and water gets evaporated, then the sugar and salt will settle on the leaves. These are in the form of white pores which are considered harmful. However, if the water remains stagnant on the leaves, it may lead to mould formation.

Conclusion

The functioning of roots is a complex process and leads to some aftereffects like root pressure and guttation. It can happen when a high level of moisture is present in the soil, either at night or during the day when transpiration is low. As a whole, this root pressure and guttation study material will surely help educate oneself about the functioning of plant roots.