hybrid rye equals the yields of wheat on wheat here, but with less fluctuation and less input of chemicals. Wheat after oilseed rape or legumes is slightly higher in yield with less disease issues. Due to my observations rye is the most "faithful" crop here on lighter or mild loam soils, giving a very constant yield from year to year. Only the falling number and lodging is everything else but constant...
The falling number is a measure of the quality of the starch, and is given in seconds. Originally it was the time a reference object took to drop down in a tube filled with flour cooked in water - the longer the better, as the starch is able to form a thick glue.

There is such a website as http://www.ryebelt.com/rb_start.html?L=1 , I like the expression "ryebelt" analog to cornbelt, showing that central europe has ideal conditions for this crop. But it´s only Germany and Poland that have a real tradition for rye bread. That can be "Schwarzbrot" or Pumpernickel, but much more rye goes to more  palatable recipes.


Hybrid wheat is available but seed is very spendy and the yield improvement is not too great - in fact not existant compared to the best conventional varieties. In rye the improvement was 20-30% from the beginning on and a no-brainer so far. My personal theory is that allo-polyploid plants (wheat) have a kind of built-in heterosis effect that makes hybrid breeding obsolete. But that´s just my theory.