I have never grown roses (in soil or otherwise) but I have been stuck by many a rose rose bush. Here is a link that has pH and EC listed for roses;
ph/ TDS/PPM Levels for Flowers
Here a few things I found on hydroponic roses;
Hydroponic Society of America (This is kind of like a slide show)
Nitrate and potassium uptake by greenhouse roses
P.S. There are so many different hybrids of roses that it may be a trial and error type of situation for variety specific information. Though I would be sure
nutrient requirements should be very similar (for soil, and hydro, except pH) for that variety, but another thing you can do is contact the
Cooperative Extension System Offices for your local area and they may be able to track down any study's on the specific variety's you need information for.