Clearwater Russet: A Dual-Purpose Potato Cultivar with Cold Sweetening Resistance, High Protein Content, and Low Incidence of External Defects and Sugar Ends

Abstract

Clearwater Russet is a medium-late maturing, russet-skinned, potato cultivar suitable for processing or fresh pack. It is notable for having a low incidence of external defects that contributes to its high U.S. No 1 yield relative to the dual-purpose industry standard, Russet Burbank. Clearwater Russet also maintains low glucose concentrations in its tubers during long-term storage making it an exceptional processing variety. With its low incidence of sugar ends and cold-induced sweetening resistance, Clearwater Russet can be stored at a temperature of 7.2°C for up to 250 days without the need for reconditioning; fry color from this storage regime is consistently ≤1.0 (USDA Fry Color Scale). This cultivar is also notable for its high tuber protein content, which was 33% greater than that of Russet Burbank. In full-season trials conducted over a 3-year period in California, Colorado, Idaho, Oregon, and Washington, Clearwater Russet had total yields slightly lower than Ranger Russet and Russet Burbank, but averaged 1% and 33% higher U.S. No. 1 yields, respectively, across all states. Average specific gravity of Clearwater Russet is comparable to Ranger Russet and significantly higher than Russet Burbank. Clearwater Russet is resistant to potato virus X (PVX) and tuber late blight and is moderately resistant to Verticillium wilt, common scab, and the common strain of potato virus Y (PVYO). Symptoms of infection with two necrotic strains of PVY were not observed in tubers of Clearwater Russet or Russet Burbank, but were observed in Ranger Russet. Blackspot bruise reaction for Clearwater Russet is less pronounced than for either Ranger Russet or Russet Burbank. The incidence of hollow heart in Clearwater Russet is intermediate between Ranger Russet and Russet Burbank. Internal brown spot has been noted as a problem for Clearwater Russet in the Columbia Basin of Oregon, but has not been observed as problematic in other growing regions. Clearwater Russet was released in 2008 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.