3.5 ETHYLENE

C2H4. The simplest alkene. A phytohormone. Kicks off many processes in plants. Probably best known that the “ripening” hormone.

Sugar Beets and Ethylene

The evidence seems pretty clear that ethylene is not a hormone that those involved with sugar beets post-harvest need to worry about too much. A paper by Fugate, Suttle and Campbell in 2010 showed that sugar beets do indeed produce ethylene, especially when damaged. And they do indeed respond to ethylene concentrations, but also the concentrations found in commercial operations are below those needed for an economic response.

At a concentration of 0.020 and 0.11 micro litres per litres, sugar beets about doubled their rates of respiration. This response (in terms of increased respiration) dissipated after a couple of days. At a concentration of 1.4, rates were still high after 4 days. However, the concentrations found in commercial stores were at most 0.054 micro litres per litre and this was at 67 days. Out to 30 days, concentrations were a maximum of 0.0017.

Maybe it does matter…

Now-expired US Patent US4021231A was claimed in 1974 by Great Western Sugar Co. They gave the following summary of the invention:

This invention is based upon the discovery that when sugar beets are treated with soil injected ethylene during growth, at 1.4 to 5 pounds ethylene per acre, the resulting sugar beets have about 20% less respiration during storage and have only about one third the usual amount of invert sugar as untreated sugar beets. This results in about a 20% increase in recoverable sucrose when the beets are processed.

https://patents.google.com/patent/US4021231

I’m very very doubtful that any farmer in this part of the world will go out after BBCH16 and inject ethylene 6 to 8 inches (15 to 20cm) in the ground for the purposes of improved storage. I’m guessing it wasn’t happening in the US either, given the patent was allowed to expire. What is exciting about this patent is that this gives an new insight to the role on-farm, in-season conditions play in the post harvest world.