Antitranspirants are substances applied to the plants for the purpose of reducing transpiration (water loss) without causing a significant effect on other plant processes, such as photosynthesis & growth. They have been used with some success in horticulture, especially in the ornamental industry.

How they reduce Transpiration (water loss)?

Antitranspirants may reduce transpiration in three different ways:

1. By reducing the absorption of solar energy and thereby reducing leaf temperatures and transpiration rates.
2. By forming thin transparent films which hinder the escape of water vapours from the leaves.
3. By promoting closure of stomata (by affecting the guard cells around the stomatal pore), thus decreasing the loss of water vapours from the leaf.

Types of Antitranspirants:

1. Stomatal closing type: They induce stomatal closing or decrease size and number of stomata which subsequently reduce the photosynthesis. For example, when Phenyl Mercuric Acetate is sprayed at very low concentrations, results in a partial closure of stomata for 2 weeks.
2. Film forming type: Plastic and waxy material which form a thin colourless film over the leaf surface and result in a physical barrier. These glossy films then reduce water loss on plants while at the same time allow them to breathe normally. Colourless plastics, silicone oils & low viscosity waxes are some examples of film forming types.
3. Reflecting type: These are most commonly clay based and increase the reflection of light from leaf surface thus reducing leaf heating and water losses.
4. Growth retardant: These chemicals reduce shoot growth and increase root growth and thus enable the plants to resist drought. They may also induce stomatal closure.

Effects on Field Crops and Plants:

An increase in yield of an annual crop was observed after the application of antitranspirants. Fuahring (1973) sprayed stomata inhibiting or film forming antitranspirants on field-grown sorghum under limited irrigation conditions, he found that grain yield increases 5 to 17% and application of antitranspirant just before the boot stage was more effective than later sprays.

References:

Websites:

• “Antitranspirants”. Agriinfo.in. N.p., 2016. Web. 5 Mar. 2016.
• “Can Antitranspirants And Antidesiccants Improve Vegetable Transplant Survival? Weekly Crop Update”. Agdev.anr.udel.edu. N.p., 2016. Web. 5 Mar. 2016.