Potato breeders and researchers strive to develop new cultivars with improved processing ability or culinary appeal, and nutritional quality, along with resistances to diseases and the multitude of pests and defects that plague potatoes.
The term “small potatoes” was once a derogatory cliché, perhaps as recently as 25 years ago. Today, small B-size colored potatoes command premium prices in specialty and even mainstream grocery stores.
Preparation ease continues to be a marketing tool. As more diverse arrays of potato products appear, demand grows for all types of potatoes. Small sizes and microwave-ready products render even the microwave method easier.
Many of today’s consumers are health-conscious. Breeders have been fulfilling this need by intensifying research and breeding clones with greater amounts of vitamins and other compounds which are increasingly identified with combating human diseases and other ailments. To do so, breeders perform laborious crosses and backcrosses, frequently accessing wild germplasm to attain desirable traits.
The USDA Agricultural Research Service (ARS) Vegetable and Forage Crops Labor-atory in Prosser, Wash., has scrutinized over 100 wild and commercially grown potatoes. Researchers found 60 different phytochemicals and vitamins, including vitamin C, folic acid, chlorogenic acid and phenolics, such as flavonoids and kukomines.
Considering just the phenolic compounds points to several health attributes of potatoes. These antioxidants have been shown to promote human health.
Significantly, colored potatoes as a group contain higher amounts of antioxidants. Both carotenoids and anthocyanins are antioxidants. Put simply, carotenoids are associated with yellow. While both white and yellow-fleshed potatoes contain these compounds, more yellow generally gives higher concentrations. Anthocyanins reflect the red to purple pigments. Red and purple skins contain some, but much higher levels are present in pigmented flesh.
Colorado State breeders and researchers have measured the vitamin C levels of microwaved potatoes. Notably, they have discovered considerable range.
The vast amount of genetic variation inherent in potatoes protracts the time required for a successful new cultivar.
Fortunately, industry, government and university collaboration is the norm in potato breeding. Not only is research data freely exchanged, but this sharing is reflected in field evaluations.
The wide range of hindrances to profitable potato growing, including diseases and environmental considerations, is greatly influenced according to area. The vast number of regional trials helps determine the adaptability of new varieties.
Breeding programs help assure that the potato industry in respective areas remains productive and competitive. For instance, the Tri-State Northwest Potato Variety Development Program focuses on Idaho, Oregon and Washington. The Potato Variety Management Institute (PVMI) releases its cultivars. The ARS in Beltsville, Md., works closely with universities and the industry in the east.
Many traits other than disease resistance and yield, including size distribution and overall appearance, prompt continued evaluation, discarding or ultimate release. Then certified seed must be increased, prolonging the process.
Year of the potato
The United Nations proclaimed 2008 as the International Year of the Potato, recognizing the importance to the world’s population and the increasing attention to food security and alleviation of poverty. The Web site, www.potato2008.org contains educational materials.
The Food and Agricultural Organization of the UN says, “The potato produces more nutritious food more quickly, on less land and in harsher climates than any other major crop.”
The Maine potato breeding program focuses on cultivars of various types that perform well in the Northeast. AF2291-10 shows early blight resistance in trials. Not for the south and coastal areas, it is highly adaptable to the north and Mid-Atlantic. Since it has chipping potential, it could also be an alternative to Snowden.
Highly resistant to scab, AF2497-2 should be released commercially by Maine soon. This fresh market cultivar can also be processed into potato chips.
Round white, high-yielding AF2574-1 may be in commercial production in 2009 if this year’s evaluations result in as favorable ratings as in the past. This Maine variety resists both early and late blight plus scab.
From the Tri-State breeding program, A093487-2R from Oregon should be released shortly. This mid to early-maturing selection produces a high percentage of US #1 tubers. Its bright red skin does not fade in storage. With few internal and external defects, shallow eyes, round shape and white flesh, it is especially attractive for the fresh tablestock market. However, it can skin somewhat during harvest.
Highly rated in taste tests, medium-maturing POR01PG20-12 features oblong tubers with red skins and red flesh. This PVMI cultivar from Washington has considerable yield potential. Specific gravity is medium.
POR01PG16-1, a long fingerling-shaped purple tuber also ranks high in taste, whether baked, steamed or chipped. With intense purple flesh, it has not displayed internal or external defects. Although low-yielding, this PVMI variety surpasses the Purple Peruvian and LaRatte fingerlings demanded by restaurant chefs. Its small tubers with low specific gravity excel in salads. In tests, the chips did not have the brown discoloration common in other purple varieties.
POR01PG22-1 produces eye-catching, flavorful chips. This banana-shaped fingerling with red skin and pinkish-red solid flesh could capture fresh market sales as well. The yields in this Tri-State breeding program PVMI release have been variable.
Many more colored cultivars are under-going trials in the Tri-State program.
Defender is most notable for its resistance to foliar and tuber late blight infection. This high-yielding, lightly russeted PVMI cultivar with consistently high specific gravity can be used for fresh markets as well as processing products directly from the field or short-term storage. It also resists early blight, potato virus X and net necrosis. It has moderate resistance to Verticillium wilt, pink rot, foliar early blight, corky ringspot and soft rot. Consequently, Defender is considered to be an excellent choice for organic production. Released a few years ago, it has short tuber dormancy and is susceptible to common scab, blackspot bruise and tuber greening. Its vitamin C level has tested almost 70 percent higher than the standard russet cultivar.
Canela Russet, a fresh market variety developed by Colorado State and ARS, produces a significantly high percentage of US #1 tubers with long-term storage potential. With oblong, medium-sized, white-fleshed tubers, its specific gravity ranks high. Canela Russet resists hollow heart and blackspot bruise, and moderately resists shatter bruise. It is moderately susceptible to blackleg. Fusarium rot may be a concern when harvesting immature tubers. Although vine growth is medium, risk from foliar early blight is moderate. It is moderately resistant to leaf roll and potato virus Y. Plus, it resists early blight tuber decay, powdery scab tuber symptoms, and has a relatively low root galling index.
CO97226-2R/R, with dark red skin and rich red flesh, is still under evaluation at Colorado State and other locations. An early cultivar, it has good yield potential, plus it produces small potatoes. Few weigh over 10 ounces and half under 4 ounces. In Washington State trials in 2007, the US #1 yield measured over 300 CWT/A, with 95 percent weighing less than 6 ounces. It has not shown any problematic tuber defects, nor any disease susceptibilities, particularly with potato virus Y and scab.
Mountain Rose, with its red skin and rosy mottled flesh, resulted from backcrossing a round white chipping potato with All Red. The semierect vines are similar in size to All Blue. The tubers store well with no grade defects. In the fresh market or as a chipping variety, this Colorado State cultivar can command a niche in the specialty marketplace.
Purple Majesty, also developed by Colorado State, shows high yield potential. Its dark skin and uniformly dark purple flesh suits both the specialty fresh and chipping markets. Early-maturing, it has medium semierect plants. It has demonstrated resistance to most internal defects, including hollow heart and shatter bruise.
Red-skinned, white-fleshed, oval-shaped Rio Colorado produces a high percentage of less than 4-ounce tubers. Also, storability is good, with excellent color retention. Early-maturing on medium vines, it resists hollow heart and is moderately resistant to black spot and shatter bruise. As suggested by its name, this fresh market cultivar is from the Colorado State breeding program.
Other Colorado State specialties under development include a new red-skinned and fleshed variety, a purple-skinned with fancy-looking purple and white flesh and a red-skinned variety with yellow flesh.
King Harry, a tablestock clone, produces small to mid-sized tubers with bright white skin and white flesh. The tubers, which remain firm and do not darken after boiling, have few internal defects. Early-maturing, the full season yield is good, averaging 96 percent of Atlantic in 18 trials, and the early yield at the end of July compares favorably with Superior. Its dormancy lasts a week longer than Atlantic. It is susceptible to common scab, but resistance includes leafhoppers and golden nematode race Ro1. This Cornell cultivar was evaluated first as T88-19, then as NY131.
Last August, ARS, with Florida, Maine, New Jersey, New York, North Carolina and Pennsylvania, released Peter Wilcox. Intended for specialty markets, its purple-skinned, yellow-fleshed oblong tubers tend to be small. Evaluated as B1816-5, it moderately resists powdery scab, but is susceptible to most other potato diseases. With darker flesh than Yukon Gold, Peter Wilcox’s total carotenoid content ranges 15 to over 50 percent higher.
Sierra Gold sports slightly flattened, smooth, oval tubers with light uniform russet skin. With yellow flesh similar to Yukon Gold, it demonstrates excellent tablestock qualities. Developed by Texas A&M, it shows high resistance to hollow heart and brown center. Also, it has displayed low incidence of internal and external defects. Compared with Yukon Gold, it is susceptible to foliar late blight but less susceptible to tuber late blight, potato leaf roll virus, potato virus M, S, X and Y. It is also more resistant to common scab and black scurf. It has given good early yields.
The work of many breeders and researchers helped with this article, including Jeanne Debons, PVMI; Charles R. Brown, Kathleen Haynes, Durey A. Navarre and Richard G. Novy, ARS; Walter De Jong, Cornell; David Holm, Colorado State; Barbara Christ and William Lamont, Penn State University; Bob Leiby, Penn State Extension; N. Richard Knowles, Washington State; J. Creighton Miller Sr., Texas A & M; and Gregory Porter, University of Maine.
The author is a writer-researcher specializing in agriculture. She currently resides in central Pennsylvania.