THE INFLUENCE OF AGING ON CELL-WALL COMPOSITION AND DEGRADABILITY OF 3 MAIZE GENOTYPES

Stem segments of the maize (Zea mays L.) hybrids LG11, Eta Ipho (EI) and a brown midrib mutant, INRA 260 bm3 (bm3) were freeze-dried, ground and analysed for cell wall content, hemicellulose, cellulose, lignin and in vitro cell wall degradability with rumen fluid. Stem cross-sections, stained with acid phloroglucinol (AP) and chlorine sulphite (CS) showed an increased intensity in staining during maturation, but no considerable difference in staining intensity was observed between genotypes. The lignin content increased during maturation with evidently less lignin in bm3 than in EI and LG11. However, cell wall degradability did not differ between the older stem segments of EI and bm3, although the amount of lignin in LG11 was twice that of bm3. It can be concluded that an increase in lignin content occurs simultaneously with a decrease in cell wall degradability within a genotype. However, between different genotypes the lignin content is not an indicator of degree of cell wall degradability.