The Glass Recycling technology sits alone with no prerequisites but I would think it should be above Canning on the tech tree. The recycling description says it provides a chance to recover glass from consumed preserved vegetables or consumed preserves. That of course can’t happen without researching Canning first, and I think the tech tree should officially reflect that relationship.
I know you can sometimes buy preserved food from a trader, but you wouldn’t do it to get the glass from the jars.
