In the last years we are facing more times with longer hot periods of drought, which has a big influence on the vegetation. Drought stress influences the growth and development of plants. The production is greatly reduced and the quality of the harvest decreased. The movement of water from the leaf into atmosphere, transpiration, can be controlled with the use of antitranspirants. Antitranspirants are chemical compounds, applied foliarly on plants, to reduce the transpiration and at the same time retain a positive water balance of the plant. Antitranspirants can be divided into three functional groups: film-forming, metabolic and reflective antitranspirants. Film-forming antitranspirants can reduce loss of water vapor from leaves to the atmosphere by increasing resistance for water diffusion. This reduces the transpirantion and maintains a positive water balance during drought. One of film-forming antitranspirants is pinolene. Metabolic antitranspirants are substances that can prevent complete opening of stomata. The representatives of these antitranspirants are fulvic and abcisic acid (ABA). Reflective antitranspirants, for example kaolin, increase albedo, which reduces the energy input, thereby reducing leaf temperature and consequently transpiration. Film-forming and metabolic antitranspirants, on the other hand, generally increase leaf temperature by reducing transpiration. With antitranspirants we can improve water use efficiency (WUE) of plant. In combination with irrigation system, we can reduce the amount of water used for irrigation. However it is important that antitranspirant has no negative effect on absorption of CO2 and photosynthesis.
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