Can I use an oven instead of a dehydrator for grains and pulses?  Dehydrators are not so common in my neck of the woods. 
You can substitute white sugar for light brown sugar with no problem, in my experience.  Make sure you substitute by weight (grams/oz), and not by volume(cups/spoons). This is because brown sugar is slightly more dense, so you get more sugar in a cup than you do with light brown. 