In-field film antitranspirant application shows potential yield protection from flowering-stage drought periods in winter canola (Brassica napus)

Crop-management solutions that simulate plant water-saving strategies might help to mitigate drought damage in crops. Winter canola (Brassica napus L.) is significantly drought-sensitive from flowering to mid-pod development, and drought periods lead to significant yield losses. In this study, the drought-protection efficacy of different chemicals with antitranspirant activity applied just before key drought-sensitive phenological stages was tested on field-grown canola in two years. Drought was artificially imposed with rain shelters. The results suggest that in-field application of 1Lha-1 of antitranspirant (Vapor Gard (VG), a.i. di-1-p-menthene) at GS6.0 (BBCH growth scale, initiation of flowering) mitigated drought-induced yield loss leading to a 22% seed-yield benefit on average over 2 years of experiments compared with the unsprayed unirrigated plots. No significant yield responses were found from application at GS7.0, with increasing VG concentrations (i.e. 2 and 4Lha-1), or with an antitranspirant with short-lasting effectiveness. The data suggest that in field conditions where drought occurs during the flowering stage, application of 1Lha-1 of VG just before the drought event can reduce yield loss. This result should encourage further work on water-saving management strategies during key drought-sensitive phenological stages as drought mitigation tools in canola and under different environments.