This is pretty interesting.

Rose gardeners often say that "Sun on the bud union promoters basal breaks." I've long suspected this was a superstition. However, the researchers found that strong light on growth-bud sites encourages buds to break from canes, so that might apply to grafts as well. This effect might also explain some of the benefits of traditional pruning practices, such as removing old canes at the base and opening the center of the plant.

Another finding: "Budbreak was subject to correlative inhibition exerted by other shoots on the plant." Does this mean that stem A is less likely to break growth buds if stem B is not deadheaded? (See the current thread on "roses getting pregranat). Or does it mean that new shoots on stem B inhibit bud break on stem A?

I cannot link to the full paper (I think it is too new). The link below is to a report.

http://edepot.wur.nl/256886

Other reports are reached from the Google link below.

Here is a link that might be useful: link to Google hits