Changes of some chemical parameters, involved in sucrose recovery from sugarcane juices, related to the susceptibility or resistance of sugarcane plants to smut (Ustilago scitaminea)

Three varieties of sugarcane, defined by their relative resistance to smut, were used to study chemical parameters involved in sucrose recovery from r aw juices. The Barbados variety is extremely susceptible to smut whereas Ja ronu is mid-resistant and Mayari is extremely smut resistant. Vegetative su garcane buds were inoculated with teliospores and cultured in field conditi ons for 12 months. Infection always resulted in a decrease in the content s ugars of juices, most markedly for Mayari plants, and an increase in the va lue of pol. The value of brix, remained unchanged for Jaronu and Barbados f ollowing infection, but increased for Mayari plants. Soluble polysaccharide s and glycoproteins of juices increase after infection in Jaronu and Mayari plants, but decreases for Barbados specimens. On this basis, glycoproteins from sugarcane juices could be considered as a factor of biological resist ance to smut.