Throw seed in water and skim off the ones that float; thereby separating the light floating seed from the heavy sinking seed. 

Is that it?  Is that all there is to it?

Doesn’t seem very technical, and a bit messy, and why not just separate the heavy seed from the light seed using a gravity table. (Seed Tech Newsletter #12 “Seed Conditioning – Separating the Good from the Bad”)?

Why would anybody want to use liquid?

Liquid Density Separation (LDS) is Very Precise.

Place 3 cups of water in a row.  In the first cup, add a non-phytotoxic salt or other tiny particle that won’t hurt the seed.  In the second cup, add one half the salt or particles, and in the third cup add nothing.  Now…drop seed into each cup.  What happens? 

All the seed floats in the cup on the left with the most particles.  All the seed sinks in the cup on the right with no particles, and the cup in the middle is somewhere in between.  OK…take the cup on the left where all the seed floats, and add water in small increments; diluting the liquid.  As the liquid is diluted, the heaviest seed starts to sink.  You can collect seed with a specific seed density at the bottom of the vessel, with each addition of water, and very precisely separate seed by its density.

Not for Field Corn

As you probably already realize, this type of separation is not for high volume, relatively low cost seed.  When seed is worth thousands of dollars per pound, this type of procedure can pay.  Certain species are also better suited to this process.  Seed that matures inside a wet fruit, like tomato or pepper seed, seem to respond better to the procedure.

That’s it for now. 
Next time we’ll talk about “Seed Fungicides and Insecticides…What’s out There?” See you then.

Keith
k.kubik@harrismoran.com