Ive noticed a correlation between hollow stems and zero root retrictions ( if we re talking about the same thing). Ive noticed the hollow rounded ridge-like stems on seedlings and veg plants, that seem to fill in, round off, and get woody by the time theyre harvested. Especially the lower stems. Plants w all hollow stems seem to be extremely vigorous and healthy, ime.
I saw 1 plant one time that finished w these stems, even the lower main. The buds looked kickass. The plant was in a big raised bed. It wasnt my plant and i didnt smoke the buds, so i cant comment on potency. But it appeared to have reached its highest potential.
Ive harvested plants w top colas that still have hollow stems, but the lower main stem isnt. One in particular i remember the top cola was huge 'tall boy can" size. But like akiymjames i didnt notice a potency increase, but only because i wasnt paying attention. This plant was in a 30gal pot flowered when its was a very small clone.
This is only a personal observation and i have zero scientific evidence, just trying to help figure this out. ive always seen these hollows as a good thing. Just wish i knew exactly whats up. I bet B would have our answers...