
One thing you have discovered, Q, is that Yellow Poplar is
a sweet wood. In other words, even the least bit of help and
it will dry nicely. (Of course, I have assumed you mean Lireodendron
Tulipifera, real Yellow Poplar.)
On the other hand many hardwoods will end split like crazy
without the help of a real end seal.

The principle behind the ethylene glcol end treatment is different
from the one behind end sealers. The E.G. is hygroscopic - it
attracts moisture. It makes the ends keep some moisture.
An end sealer on the other hand is preventing evaporation.
As you can see..., two differing means to a similar objective.
Another point in regard to the E.G. is that on White Oak, for example
(Quercus Alba - the "real" white oak) that chemical would evaporate
before the White Oak began to really dry. Because
of this, such an ornery wood would begin to end check badly.
Poplar, Walnut, Black Cherry - oh yeah, they are sweet in comparison.

Interesting how God designed so many woods with so many personalities, no?
Phil L.