Analytical pyrolysis as a tool to determine chemical changes in maize stovers during growth

Stovers of five maize hybrids harvested at various growth stages were subjected to pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) and conventional analyses for fiber and protein, i.e. Van Soest's neutral detergent fiber (NDF) and Kjeldahl crude protein (CP). The aim of the experiments was to find pyrolysis markers of the growth stage and to ascertain what degree of correlation exists between analytical pyrolysis and conventional analyses of fiber and crude protein. Correlation coefficients higher than 0.90 in absolute values were found for some pyrolysis fragments and NDF, CP and growth stage. Such fragments included lignin, carbohydrates and protein thermal decomposition products. In conclusion, PY/GC/MS can monitor chemical changes in the main components of maize stover during maturation with the advantage over the conventional assays NDF and CP of providing molecular information and of being faster and much simpler.