Saturday, July 4, 2015

The Effects of Flooding on Roots

Weather conditions that occur after flooding are just as important for plant survival as during flooding. Prolonged saturation of soils will stress oxygen-starved roots. 
  • Cooler temperatures allow root and seedling diseases to develop, while plant growth is minimized. 
  • Cool, cloudy conditions also limit plant recovery from physical damage caused by silt and crop debris. 
  • Hot and windy conditions following flooding also do not provide favors to the roots.  
  • Rapid soil drying can cause crusting that limits plant growth. Continued drying of soils is stressful if prolonged soil saturation has resulted in root die-back or limited root system expansion.
 Growers should carefully evaluate crop damage and check with an agronomist and crop insurance agent to get more opinions before tearing up the stand and replanting. Crops that look yellow and weak can often recover, especially with favorable weather conditions. If plant meristems remain healthy, survival chances are high; if meristematic tissues are soft and discolored, recovery is more than likely not in favor. New growth will require several days after water drains from the field. Check roots for white, healthy regrowth of roots.  Patience is a great key to decision making in this process.
Corn can only survive two to four days of totally saturated soil condition when the growing point is at or below the soil surface. This being V5-V6 growth stage.  Warm temperatures often shorten the survival period to only 24 hours, but cool temperatures increase survival.  Larger corn can handle saturated soils.
When soybeans become flooded, oxygen is very limited for respiration.  Flooding in general has a negative impact on the symbiotic nitrogen fixation and mycorrhizal colonization of the roots. Soybeans can survive 48 hours underwater easily, and can even survive submersion for a week under favorable condition both during and after a flooding event.

-Courtney Brown; Burrus Missouri Intern

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