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.
Received for publication 5 May 1986. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.