Chilling Injury, Respiration, and Sugar Changes in Sweet Potatoes Stored at Low Temperature

Abstract

External chilling injury symptoms, primarily surface pitting followed by secondary fungal decay, developed in six sweet potato [ Ipomoea batatas (L.) Lam] cultivars after an exposure to 7°C for 2 weeks or more followed by storage at 15.6°. Internal chilling injury symptoms, primarily darkening of the cambium and vascular bundles, were observed in noncured ‘Whitestar’ and ‘Rojo Blanco’ roots after exposure to 7° for 3 weeks and in ‘Centennial’ after exposure to 7° for 4 weeks followed by storage at 15.6°. ‘Jewel’ was the cultivar most tolerant to low temperature. Chilling injury and respiration rate were greater with increasing lengths of exposure to 7° and were greater in noncured than cured roots. Enhanced sucrose and total soluble sugar content occurred at 7° compared to 15.6°. The primary sugar responsible for low-temperature sweetening was sucrose, but there was considerable variation among cultivars in the extent of low-temperature sweetening and specific sugar changes.