About 80% of global farmland is under rain-fed conditions and most of it prone to drought, which limits crop productivity. Due to climate change, drought will become more frequent and severe threatening world food security.Antitranspirants, materials that reduce transpiration, could potentially result in greater food production by realising more of a crop's potential yield during drought. Despite antitranspirants also reducing photosynthesis, research has shown that they can mitigate drought stress resulting in increased grain yield.Although this paper is not restricted to specific years, part of it is a systematic review of 173 original research articles published between 2009 and 2018.Overall, the analysis suggests that interest in the potential of antitranspirants is growing.One major achievement in antitranspirant research during the past decade was establishing the optimal timing of application of the substances, which is linked to reproductive processes most vulnerable to drought. Despite research evidence of the efficacy of antitranspirants in ameliorating drought stress, they are not widely used for commercial arable crop production. However, in fruit horticulture, 2 products with antitranspirant effects are being used for various non-antitranspirant purposes such as synchronising fruit ripening, enhancement of nutritional quality, protection against sunburn and controlling diseases and insect pests.

No abstract

Global food security is at risk due to the predicted climate change, making it imperative for agronomists to provide adaptive technologies that will sustain and improve food production. Rainfed agriculture, prone to drought, covers an estimated 80% of global cropland. One of the adaptive technologies is the use of antitranspirants – products that are applied on plants to reduce transpirational water loss and increase crop performance under drought conditions. The benefits of improving antitranspirant adoption in drought mitigation are expected to be high, especially in many drought-prone low-income countries where crop production is almost wholly dependent on rainfall. The objective of this article was to review the commercial uses of antitranspirants in food and non-food crop production. The review revealed that in horticulture, antitranspirants have several commercial uses, in addition to drought mitigation, such as transplanting shock amelioration, protection of fruit against sunburn, enhancement of nutritional quality, synchronising fruit ripening, protection of fruit and nut trees against diseases. Use of antitranspirants in arable farming has been neglected for three main reasons: first, arable crops have lower market value, for example, in Melbourne (Australia) in October 2022, a tonne of grapes was worth US$ 2694.82 compared to US$ 277/tonne of wheat. Second, molecular genetics applied to crop breeding has risen as an alternative approach to drought mitigation, shifting attention from antitranspirants. Finally, the erroneous research conclusion in the 1970s that antitranspirants could not increase yield because they reduced photosynthesis discouraged commercialisation of antitranspirants in arable farming. An antitranspirant breakthrough to either lower the cost or create a multi-purpose product is needed for the production of arable crops, especially major cereals, as has been the case for non-drought amelioration uses in horticulture.

Film antitranspirants (e.g. di‐1‐p‐menthene) and metabolic antitranspirants (e.g. exogenous ABA) can be used to protect grain crops from drought, particularly during reproductive development. Here, we compared effects of di‐1‐p‐menthene (1.0 L/ha) and exogenous ABA (100 µM) on well‐watered and droughted spring wheat in two glasshouse experiments. Progressive drought was imposed in the first experiment, controlled drought in the second, both from flag leaf emergence. Antitranspirants were applied at flag leaf emergence, except in the controlled drought experiment where additional ABA applications were made at four further stages up to anthesis‐complete. Measurements were taken for endogenous ABA, stomatal conductance and photosynthesis during reproductive development, and yield components at maturity. Both progressive and controlled drought elevated leaf ABA, less so in di‐1‐p‐menthene‐treated plants, whereas in exogenous ABA‐treated plants leaf ABA was elevated further. Overall, both antitranspirants improved yield under reproductive‐stage drought, more so for controlled drought. Grain yield was negatively associated with reproductive‐stage leaf ABA concentration except that raising leaf ABA concentration with multiple exogenous ABA applications was associated with high yield. In conclusion, both antitranspirants generally reduced effects of reproductive‐stage drought on yield despite having contrary effects on leaf ABA.