The role of root sugar content on the susceptibility of sweetpotato cultivars to soft rot

In studies conducted in Tanzania in 1999, Rhizopus oryzae which causes soft rot was identified as the major post-harvest pathogen of stored sweetpotatoes (Ipomea batatus). Variations in cultivar susceptibility to this pathogen were also observed. In the present study, the role of root sugar content in tubers was evaluated against the observed variation in cultivar susceptibility to this pathogen. The fructose, glucose and total sugar content within the sweetpotato roots influenced cultivar susceptibility to R. oryzae. The concentrations of these sugars in the roots were significantly but negatively correlated with cultivar susceptibility to R. oryzae. These results suggest the possibility of using root sugar content variable to select sweetpotato cultivars for resistance against R. oryzae.