Transpiration is the process in which plants lose water vapor and is part of a plants natural water cycle. This process is similar to sweating in humans, where the water we take into our bodies exits through our pores. In plants, water taken in by the roots exits the plant through tiny pore-like holes called stoma or stomata (plural), as well as the cuticles and other plant tissue. A majority of the water lose occurs through the stomata. The stomata are typically found in the highest concentration on the bottom sides of the leaves of most plants.
The rate of transpiration is effected by atmospheric changes like changes in temperature, humidity, or drying winds. The size of the stomata’s opening also effects the rate of transpiration and it’s size can be influenced by these changes. The transpiration rate can be reduced dramatically with the use of antitranspirants like Nature Shield™
Transpiration should be a concern for growers and gardeners especially when harvesting or transplanting, most often the amount of fibrous roots is reduced during these times. When the roots are disturbed this effects the plants ability to take up and replenish water that is lost through transpiration. Supplying adequate water is crucial until the plant can regenerate the fibrous roots needed for water uptake. The use of antitranspirants does not eliminate the need for water in the root zone. Antitranspirants aid the plant helping it retain water and plant vigor until the roots can be regenerated. Other times of concern include extreme temperature changes or spikes as well as during the shipping of plant material. During shipping for example plants may be exposed to drying winds or perhaps your shipping under refrigeration, in both cases water loss is a concern. During heat spikes the stomata open allowing large amounts of water vapor to be released, sometimes faster than it can be replaced especially in water stress conditions where there is not enough water available in the root zone.
Antitranspirants are compounds that are designed to reduce the loss of water vapor from plants, a process known as transpiration. Most water loss occurs through the leaves of plants. Leaf surfaces are covered with tiny openings called stoma. These openings are where plants take in carbon dioxide and release oxygen during photosynthesis. Water is also released during this process. On most plants a majority of the stomata (plural) are located on the bottom side of the leaves. The stems and branches of the plants have stomata as well, though most of the water loss in these areas happens through the cuticles.
There are three common types of antitranspirants, the most common being a foliar spray. Not surprisingly the most common as this is where most water loss occurs, and they are very effective in reducing water loss. This form of antitranspirant is sprayed on all surfaces of the plants forming a permeable protective plant coating that helps plants retain water while still allowing plant to take in carbon dioxide and release oxygen, thus not affecting plant growth. The protective plant coating created by this type of antitranspirant acts as a barrier from stresses caused by nature. It shields plants from an increase of water loss during temperature extremes and drying winds. It provides added protection from stresses related to the processing and handling of plant material, for example summer digging, transplanting material during a growth flush. When shipping material to hotter or colder regions it helps acclimatize plants as well as protecting them from water loss when shipping plants under refrigeration.
The second type of antitranspirants are metabolic inhibitors. The most common being (ABA) Abscisic acid. ABA is also called Abscisin originally found to induce abscission, and Dormin originally found to induce dormancy. ABA is a naturally occurring plant hormone that plays several roles in regulating various stages of plant growth. ABA is also produced in response to plant stresses and induces the production of plant proteins that are associated with acclimating plants to plant stresses. When plants experience water stress due to dry soil conditions the roots synthesize ABA and send chemical stress signals to the leaves. Changes take place in the leaves in response to these stress signals effecting the osmotic potential of the guard cells that surround the stomata. This causes the stomata to close reducing the amount of water lost through transpiration so the plant is able to retain as much water as possible for survival.
This naturally occurring plant hormone has been synthetically reproduced resulting in a man made (PGR) plant growth regulator. While this type of antitranspirant can be applied as a foliar spray it does not form a protective plant coating like the antitranspirants mentioned in Type 1. While this type has primarily been used as a foliar spray it can be applied as a soil drench to be taken up by the roots. The downsides to using ABA as an antitranspirant include but are not limited to it’s overall cost and the duration of it’s effectiveness, usually a matter of days. In contrast the film forming antitranspirants like Nature Shield™ form a protective plant coating over the leaves and plant surfaces that reduce water loss through the stomata, cuticles, stems and other plant tissues that can last for weeks or months. The film forming antitranspirants are also less expensive.