In order to efficiently utilize wheat straw, the systematic examination of their cell wall components, chemical structures, morphology, and relation to the physicochemical and mechanical properties is necessary. Detailing of node and internode signifies their different features and characteristics which can ultimately lead to their separated processing for enhanced efficiency and higher value-added biorefinery. In this study, distinct variations were found among characteristics of node and internode, inner and outer surface. It was revealed that the node has more extractives, Klason lignin, and ash content than the internode; higher contents of extractives and ash in the node are related to the thicker epidermis tissue. Hot water followed by mild steam pretreatment was used to examine the effects on the characteristics of wheat straw. The results showed: (1) reduced level of waxes and Si (weight %) from the outer surface and (2) significantly lower (P < 0.05) extractives content in both internode and node.
Keywords: node and internode; physicochemical characterization; surface chemical distribution; wheat straw.