Flood priming and leaf loss in Brassica oleracea
Man-made climate change continues to create more frequent and severe weather events. One of the predicted consequences is an increased amount of flooding. In the next 65 years, flooding events are expected to cause a 20-fold increase in economic damage with the agricultural industry suffering many losses. In order to examine the effects of flooding and soil inundation stress on crop plants, we collected twenty samples of white Russian kale (Brassica oleracea) from a field in eastern Connecticut (Adamah Farm, Falls Village CT) that experienced a gradient of flooding stress in September 2014. We transplanted these field samples into a growth chamber at Bard College (Annandale-on-Hudson, NY) and flooded the soil of half of them for 10 days while maintaining the other half as well-watered controls. Above- and belowground biomass were measured before and after soil inundation.
We did not find any difference in overall biomass between any groups. However, kale that hadn’t been pre-exposed to flooding in field conditions increased leaf abscission and lost up to half of total leaves during the soil inundation period. Kale that had experienced field flooding retained nearly 100% of total leaves. The observed ability to retain leaves in flood-primed plants should affect future growth capacity. We also found that plants that experienced soil inundation in the lab produced more aerenchymous tissue than control plants. We conclude that kale acclimates to temporary soil flooding both by its capacity to form aerenchymous tissue and potentially due to additional physiological changes not measured here. This may mean that exposing plants to small amounts of soil inundation early in the season could prime them for improved performance during natural floods.