The preliminary indication would suggest that this is probably a result of fungicide toxicity from the seed treatment.

For the overcoming of phytotoxicity an excellent antidote is humic acid and kelp.

The swollen hypocotyl with dwarving might be associated with Giberellic Acid inhibition and the generation from the phytoxicity of excessive ethylene. 

Take good notes and avoid those products with this negative reaction for future trials. 

This thickening of the hypocotyl is a typical symptom of phytotoxicity of fungicides.

Triazoles fungicides  applied as seed dressing may cause this symptom. Often this thickening comes with fissures in the hypocotyl.

i had similar fungicide effect on Artemisia spp.. in my experiment treated seed couldn't germinate. 

Thank you all