If you meant cellulase, find this paper: Miller et al. (1960). measurement of carboxymethylcellulase activity. Analytical Biochemistry 2: 127-132. It talks about the use of potassium iodide as a replacement for DNSA.
You can use the Phenol-sulphuric technique, this is the reference:
Dubois, M., Gilles, K. A.; Hamilton, J. K.; Rebers, P. A. y Smith, F. (1956) Colorimetric Method for Determination of Sugars and Related Substances. Analytical Chemistry, 28(3): 350-356.
Hi Chang Elven, I'm traying to implement NREL method but I could not get the good values for rapeseed straw, my glucose % is around 10%, have you had this problem?