Master of Science (MS)


Plant, Enviromental and Soil Sciences

Document Type



Burgeoning demand for sweetpotato [Ipomoea batatas (L.) Lam] is being driven by strong consumer consumption of fries and robust fresh market sales. Acreage has rebounded to meet needs, but increased supply has weighed negatively on fresh market prices, and processing sweetpotato is generally at a low price point. Growers are challenged with increasing production costs and labor is the most expensive input; reducing labor costs through mechanized harvest is critical. Many popular varieties of sweetpotato are highly susceptible to skinning damage and the problems that are associated with exposed root flesh such as rotting, weight loss, and sunken areas. The present study compared methods to assess skinning damage and determine if it is possible to breed for a more skinning resistant variety to aid in further mechanization. A torque wrench was found best at quantifying the amount of force required to cause skinning damage. A two year study of a parent and offspring population using the torque wrench found a heritability estimate of 0.10 on an individual plant basis and a 0.63 heritability on a family basis. It is assumed that an estimate above 0.50 is sufficient to improve a trait and data showed utility using families in breeding scheme, albeit this brings complications. The research also examined genes differentially expressed at skinning injury sites in 2 different environments. Over expression of genes involved in healing may decrease damage that does occur after skinning damage and complement a more durable skin. Consequences of skinning are lessened by curing roots (32° C; 85% relative humidity for 5 days); wound sites are rapidly healed with nominal desiccation. Cyt P450 and Ext, genes associated with periderm formation and wound healing, were found up-regulated in a curing environment compared to skinned sites at ambient outside conditions (conditions varied from approximately 26-30°C, with 50-70% RH ) over multiple time points (2 h, 4 h, and 24 h after skinning). Multiple genes associated with stress were found up-regulated in the ambient conditions. It is hypothesized that selection of genotypes with a more durable skin and enhanced repair mechanisms may further the quest towards mechanized harvest.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

LaBonte, Don