Mechanical properties and compositional characteristics of beet (Beta vulgaris L.) varieties and their response to nitrogen application

Mechanical properties of sugar beet are important during harvesting and processing. To potentially correlate mechanical properties with structural features of cell wall polymers, four different Beta varieties (Beta vulgaris L.) were characterized for their mechanical properties and cell wall composition. In addition, the influence of nitrogen fertilization was analyzed. Additional nitrogen fertilization only slightly influenced mechanical properties and cell wall composition. Hardly any structural differences of cell wall polysaccharides were observed for all Beta varieties. Slight differences in alcohol insoluble residue and protein contents, in amino acid profiles of proteins, and in esterification degree of pectins were found. The Beta varieties differed in their contents of cell wall bound phenolic components, and particularly in their dry matter contents. Analyses of mechanical properties of the Beta varieties demonstrated differences in tissue firmness and compressive strength. However, no evidence was found that the observed differences of cell wall composition are responsible for the divergent mechanical properties, with the exception of water contents that were higher in samples with less compressive strength.