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Drought
With sufficient rains to rescue a drought situation, flowering canola plants can flower for longer to increase seed production and yield potential. If plants are already done flowering and then rains come, can canola resume flowering? Not much has been done to explore this, but literature on canola suggests that:
- If drought and heat stress occurred earlier (like at early flower) and then subsided, the plant will likely recover better than if this stress occurred later (like at seed and pod formation).
- Flowering on side branches can compensate for main stem yield loss due to drought and heat stress. So, if side branches are formed and then flower, they will hopefully make up for some lost yield on the main stem.
- Flowering cannot re-occur where it has already occurred. The site of an aborted flower will not produce a second flower.
- We assume there will eventually be a “point of no return” where the plant will no longer try to produce flowers, but we don’t know when that is. With moisture at harvest, we have seen regrowth start from cut stems, but we don’t know whether regrowth can occur from standing stems that are moving toward maturity. “Re-flowering”, or the production of side branches which then flower, will be less likely as the plant continues to develop to maturity.
Hail
Canola will resume flowering after hail knocks off flowers and branches. Canola will flower longer to compensate for these loses and, with enough time, can recover if hail knocks off a large percentage of flowers.
In light hail, canola can sometimes over-compensate and produce even higher yield. In serious hail situations where entire flowering branches are knocked off, plants that are still actively flowering can produce new branches. There will eventually be a “point of no return” where the plant will no longer try to produce flowers, and reproductive development will continue to maturity, but we don’t know exactly when that point might be. With moisture at harvest, we have seen regrowth start from cut stems. This is not ideal for harvesting, but it shows that regrowth can occur very late in the season.