Infinitesimal,
I've not had the pleasure of growing either one of those strains, I've read though that both are slow in veg... and I imagine the x would give some hybrid vigor to the offspring... Is that true?
Sour bubble is definitely one of the most slowly vegetating Lines Ive experienced.
Romulan is now considered old school by many and is roughly a 40/60 I/S ( colombian X Korean, as Ive always heard it); even though it has an Indica dominant growth pattern, its far from the slowest veggers that Ive experienced... but Ive only grown it from a cutting so I can't speak to the vigor of Romulan in seed form, although I am popping some older Next Gen Romulan beans right now just for fun
Sour Bubble is very much Inbred (in a good way of course ) and likely is the reason for the slow growth... that and the Indica predominance. So out crossing it, especially to strains with Sativa genetics in them should in general result in more vigorous plants.
and so far it has been reported in testing, that the plants are vigorous... hopefully you will begin to see grow threads on them and the other two Sour Bubble hybrid strains The China Syndrome and Sour Purple shortly.
EDIT: I try and reserve the term "hybrid vigor", for pure Sativa X Pure Indica Hybrids but it always helps to introduce fresh genes into highly Line bred or BX'd strains for the purpose of vigor and resistance... as a wider diversity of genes promotes higher survival and "thrival" rates ( yeah, thats right I just invented a new word )
Thrival Rate: the percentage at which individuals of a particular Genotype thrive under specific environmental conditions..LOL...
hope that helps,
Peace
Infi
man, i guess someone beat me to thrival but it has nothing to do with thrival rates so... LOL