Metabolic and film antitranspirants both reduce drought damage to wheat yield despite having contrasting effects on leaf ABA

Abstract

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.

Yield improvement with antitranspirant application in droughted wheat associated with both reduced transpiration and reduced abscisic acid

“…Despite the considerable inhibition of photosynthesis, reduced transpiration with DpM during the reproductive growth stage drought was associated with higher yields, in agreement with past research (e.g., in wheat [Abdullah et al, 2015] and rapeseed oil [Xiang et al, 2022]). Under progressive drought, reduced transpiration can be beneficial for maintaining plant development and yield (Faralli et al, 2016;Mphande et al, 2022). This is corroborated by the regression analysis as transpiration was negatively associated with yield and most of the yield components under drought stress conditions.…”

“…Combining DPM with exogenous ABA (the DpM + ABA treatment) eliminated any significant benefit to yield due to DpM. Under progressive drought, Mphande et al (2022) observed that exogenous ABA was ineffective in increasing spike ABA concentration; although it consistently increased the accumulation of the hormone in well-watered plants. Once ABA reaches an upper limit, negative feedback mechansims prevent its further accumulation (Liu et al, 2016).…”

Commercial uses of antitranspirants in crop production: A review

“…Metabolic ATs are a group of substances that have hormone or hormone-like effects (Das and Raghavendra, 1979). Their benefit to plant growth under water stress conditions lies in inducing partial stomatal closure by acting on guard cells, thereby reducing water loss (Mphande et al, 2021a). Examples of metabolic ATs used for improving water status in crops include ABA in artichoke (Shinohara and Leskovar, 2014) and wheat (Zhang et al, 2016).…”

The Role of Antitranspirants in Mitigating Drought Stress in Plants of the Grass Family (Poaceae)—A Review

“…The beneficial effect was increased when it was applied together with hydrogel [63]. The exogenous use of chitosan has been demonstrated to improve many diverse parameters such as increases in chlorophyll content, carotenoid, yield parameters, flag leaf area, shoot dry weight, and water use efficiency (WUE) [56]. Moreover, other studies have shown that after the application of chitosan, parameters such as plant height, number of tillers per hill, flag leaf length, and flag leaf width increased compared to the control sample in water deficit.…”