Peer review

Drought stress reduces seed crop yields in part by causing reproductive sterility associated with increased endogenous ABA. Application of the film antitranspirant, di-1-p-menthene, during reproductive-stage drought has been shown to ameliorate yield loss in wheat but the physiological processes involved are not understood. Using rain shelters to simulate Mediterranean-type terminal drought, we studied the possibility that application of the antitranspirant reduces both endogenous ABA concentration and the subsequent yield loss. Di-1-p-menthene was sprayed on droughted spring wheat plants (cv, Chilham) at 1.0 L/ha in two separate field experiments, at three growth stages between stem elongation and spike emergence in 2018; and at four growth stages between stem elongation and anthesis in 2019, with droughted but unsprayed plants serving as the control. Drought stress increased endogenous ABA but decreased yield. Di-1-p-menthene application reduced endogenous ABA concentration by 33% and 40%; and improved grain yield by 16% and 15% averaged across all growth stages in 2018 and 2019, respectively. The consistent effects of di-1-p-menthene in both years suggests that the mechanism of drought stress amelioration by the film antitranspirant is related to reduced endogenous ABA concentration during key growth stages.

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