You may be right there Testing, but when I check my preferences in Lightroom, I have a choice of ProPhoto RGB, Adobe RGB (1998) or sRGB and the only one that preserves the full range of colours is ProPhoto RGB. Problem is that the only colour space which I can use on my D90,Lightroom 3 and HDR Efex Pro is Adobe RGB (1998) (and that is assuming that the Adobe RGB on the D90 is Adobe RGB (1998)).
I changed my camera from sRGB to Adobe RGB, changed the Lightroom and HDR Efex Pro preferences to 1998 and took another picture and checked again - still the same. This is with the default preset in HDR Efex Pro which supposedly does not make any changes to saturation etc. yet the greens still look too yellow.
What colour space set-up do you use in your camera/Lightroom/HDR Efex Pro?