We've had an exceptional response from UBC researchers contributing material for UBC Research Week, so even though this is the last official day, we're going to continue highlighting UBC Research next week.

Ruth worked with Dr. Andrew Riseman from the UBC Faculty of Land and Food Systems and David Bradbeer & John Hart of The Centre for Sustainable Food Systems at UBC Farm for today's entry on sweet potato cultivar trials for Pacific Northwest production. Today's photographs are by David Bradbeer and are part of a set available on Flickr: Sweet Potato and UBC@Flickr.

Andrew and David write:

"The Centre for Sustainable Food Systems at UBC Farm (CSFS), within the Faculty of Land and Food Systems, promotes food system sustainability through research, teaching, and outreach activities. As part of their research activities, new crop evaluations are ongoing. The climate of the Pacific Northwest represents a challenge for growing many tropical and sub-tropical crops due to relatively low temperatures. However, many valuable crops fall within this category and if suitable genotypes were identified, could add important diversity to a production system. One crop currently under evaluation is sweet potato, a tropical plant in the genus Ipomoea (morning glory). However, short growing seasons can limit yield, especially in cultivars that require >120 days to reach maximum yield. Ideally, sweet potato cultivars that reach maturity early would be appropriate choices for small-scale farmers in the Pacific Northwest that wish to diversify the selection of vegetables they can offer to their clientele."

"Nine sweet potato cultivars were collected, propagated and grown at the CSFS in 2006 and 2007 as part of a pilot feasibility study. The cultivars evaluated included 'Excel', 'B18', 'T68', 'Georgia Jet', 'Georgia Jet Bicolour', 'Korean Purple', 'Owairaka Red', 'Toka Toka Gold', and 'Nancy Hall'. Results indicated that sweet potatoes can be grown in this climate but that significant challenges remain including heat unit accumulation (i.e., time to maturity) and soil-pest management. Therefore, the 2008 trials focused on evaluating earliness and wire-worm resistance of the eight best cultivars from the previous seasons."

Ruth adds: Wireworm is a stage in the lifecycle of a group of beetles called the click beatles, from the family Elateridae.

Andrew and David continue: "In 2008, the trial compared yields from plants harvested at 90 and 120 days after planting. Initial results indicate significant differences among cultivars and that some were sufficiently suited to short season growing (i.e., those that produced a marketable amount of biomass before 90 days), and therefore appropriate for small-scale production in the Pacific Northwest. In addition, several remaining challenges were identified and include: the propagation of planting stock, the cost-effective use of clear plastic mulch to provide essential early-season soil heating, management of wire worm infested soils to avoid excessive root damage, and the establishment of climate-controlled systems for curing the roots after harvest."

"This sweet potato project represents real-world agroecology in action. Small-scale crop evaluations such as this present an ideal opportunity to train the professionals needed to assess, restructure, and develop the cropping systems of the future. However, much work remains for both assessing the role of sweet potatoes in the Pacific Northwest crop rotations but also in designing truly sustainable production systems and training those who will manage them."