Guttation mainly occurs in tropical plants during hot and summer days. The droplets are mainly found on surface of leaf or at the apex part of leaf and can be seen during late night or early morning.
“Guttation is defined as the exudation of sap in the form of droplets through a special pore present in the leaf called hydathode.”
The droplets(sap) oozed on the leaf surface contains water along with other minerals.
Mechanism of Guttation
Hydathode are cell which plays important role during guttation mechanism. It is made up of group of loosely connected parenchyma cells. These cells are called as epithem. Epithem are supplied with water conducting xylem cells.
It occurs simply due to high root pressure which forces higher water absorption in the root. Due to lower transpiration at night time, the excess water absorbed by root is passed to the xylem cells present in epthem of hydathode. Thus, the excess water along with other nutrient and minerals absorbed from root oozes out from the hydathode pore in the form of water droplets.
The composition of water resulting from guttation contains variety of organic and inorganic solutes, salts, minerals, N, P, K, Na, Mg ions etc.
The volume of water lost during guttation is generally small. However, a young leaf of Colocassia nymphaepholia can lose 100ml of water in a single night.
Examples of Plants Showing Guttation
Potato, Tomato, Balsam, Trapaeolum majus, Saxifraga, Colocassia nymphaepholia, Colocassia antiquorum, grasses, strawberry, Sulphur ovinus and some other vascular plants.
Image Caption: Sulphur Ovinus (Tree Mushroom) showing guttation
Importance of Guttation in Plants
There is no any proven advantage of guttation in plant. However, it is supposed to release the excess pressure and developing progressive absorption capacity in plants.
Disadvantage of guttation are:
- It is uncontrolled phenomenon which cause excess loss of water.
- Frequent guttation may cause mineral deficiency in plants.
- It may cause leaf burn due to residual (salts) accumulated in the leaf.