Simulated seawater flooding reduces oilseed rape growth, yield and progeny performance

Of the many threats to global food security, one of the most pressing is the increased incidence of extreme weather events. In addition to extreme rainfall, a combination of global sea level rise and storm surge is likely to result in frequent episodes of seawater flooding in arable systems along low-lying coasts. Hanley et al. elucidate the effects of simulated seawater and freshwater flooding on the survival, growth and reproductive potential of four cultivars of the important seed crop, Brassica napus [canola, or oilseed rape (OSR)].

The effect of root zone immersion in deionized water
The effect of root zone immersion in deionized water (Dw) and seawater (Sw) on mean (± s.e.) seedling dry mass of four oilseed rape (Brassica napus) cultivars (‘Cracker’, ‘Cubic’, ‘Agatha’ and ‘Astrid’) of plants grown from seeds collected from parent plants subject to transient immersion (24 or 96 h with a zero hour control, at growth stage 1.3–1.6). n = 4 for all treatment/cultivar combinations except ‘Agatha’ 24 h Dw where n = 3, and ‘Cracker’ 96 h Dw and ‘Agatha’ 96 h Swwhere n = 2. Source: Hanley et al. 2019.

Oilseed rape growth and reproductive responses were unaffected by freshwater, but seawater negatively affected growth and siliqua number for all cultivars, and seed mass for two (‘Agatha’ and ‘Cubic’). In addition to impacts on crop yield, the growth of seedlings cultivated from seed collected from maternal plants subjected to seawater immersion was also reduced

Their results demonstrate the potential impact of seawater inundation on coastal cropping systems; although OSR may survive acute saline flooding, there are longer term impacts on growth and yield for some cultivars. The threat may necessitate changes in land-use practice and/or the development of salt-tolerant cultivars to maintain economically viable yields. In addition, by evidencing a hitherto unknown effect on reproductive performance (i.e. reduced seed yield) and subsequent seedling growth, Their study highlights an important potential impact of coastal flooding on plant community dynamics for (semi-) natural habitats.

Further reading

Hanley, M. E., Hartley, F. C., Hayes, L., & Franco, M. (2019). Simulated seawater flooding reduces oilseed rape growth, yield and progeny performance. Annals of Botany. https://doi.org/10.1093/aob/mcz026