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:
- By reducing the absorption of solar energy and thereby reducing leaf temperatures and transpiration rates.
- By forming thin transparent films which hinder the escape of water vapours from the leaves.
- 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:
- 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.
- 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.
- Reflecting type: These are most commonly clay based and increase the reflection of light from leaf surface thus reducing leaf heating and water losses.
- 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.