OFRF Research Partner Releases New Varieties of Open-Pollinated Sweet Corn


July 24, 2015 - Two new varieties of open-pollinated, sweet corn will be available in limited quantities for the 2016 planting season, thanks to ongoing research by Oregon farmer and OFRF research partner Jonathan Spero.

The commercial release of Top Hat and Tuxana sweet corn seed is a welcome milestone in the movement to revive traditional crop breeding, and increase the selection of organic-friendly varieties whose seed can be saved by farmers. Spero’s sweet corn breeding project was supported by a four-year research grant from OFRF.

Spero expects his new varieties of white and yellow sweet corn to see additional improvements in coming years, as they are planted in new regions and the seed is saved and replanted by numerous farmers and gardeners.

“I have shown how these crop improvements can be made, and new varieties created, without advanced technology or large amounts of money,” Spero said in his report. “Others may see that they too can step up from gardening or farming to plant breeding and crop improvement. It may help return crop improvement and varietal ownership to the farmer.”

In addition to breeding for enhanced sweetness, Spero worked to make Top Hat and Tuxana more competitive against weeds, better able to resist insect pests, and tolerant of lower-fertility soils – all attributes of special value to organic farming systems.

According to Spero’s report, breeding and improvement of open-pollinated corn was largely abandoned 60 to 70 years ago, with the introduction of hybrid seed varieties. Most hybrid seeds are the product of traditional breeding techniques, and therefore not considered GMOs. But hybrid offspring do not uniformly resemble the parent plant, and farmers relying on hybrids must purchase new seed every year.

In addition to fostering dependence on seed companies, hybrids do not allow farmers to participate in ongoing crop improvement, which over millennia has resulted in a rich heritage of regionally-adapted crop varieties around the globe.

Spero began his research using the hybrid sweet corn Tuxedo, as well as a traditional, multicolored Anasazi maize. Yellow-eared Top Hat is stabilized version of Tuxedo, and Tuxana is a white-hued blend of Tuxedo and Anasazi parentage. Both varieties were selected over 7 generations for sweetness, size and vigor, quick growth to outrace weeds, tightly-wrapped husk to deter pests and ability to thrive in lower-fertility soils.

Spero’s final research report, available on OFRF’s website, details how farmers and gardeners can use low-tech breeding techniques to contribute to the ongoing improvement of Top Hat and Tuxedo, and other open-pollinated maize, by selecting and saving the best seed from their fields. Techniques include thinning to favor the fastest-growing seedlings, choosing plants with the best husk coverage, marking matched pairs of ears on the most vigorous plants, and tasting ears in the field to identify the sweetest individuals.

He also describes how best to dry and store seed for the next season, and how corn seed without Anasazi genetics can be further sorted for sweetness during the drying process. In non-Anasazi corn seed, the seed with the most sweetness are the slowest to wrinkle as they dry, allowing for those seeds to be marked and saved. In Anasazi corn, the genes that determine sweetness are apparently more diverse, and slow wrinkling is not a good indicator of the sweetest seed. However, selecting for slow wrinkling in the corn with Anasazi parentage resulted in a creamier-tasting ear, a pleasant surprise to researchers.

Spero found that human taste buds were a better judge of sweetness than a high-tech refractometer. The refractometer was fooled by soluble solids other than sucrose, and was unable to perceive off-tastes that humans tasted immediately. Field tastings at Speros’ Lupine Knoll Farm in Grants Pass, Oregon, became an annual community event, with dozens of tasters munching their way down rows of corn and selecting the tastiest ears.

Limited amounts of Top Hat and Tuxana are available from FEDCO seeds, Siskiyou Seeds, Uprising Seeds, Bountiful Garden Seeds and Horizon Herbs. Spero hopes to have 500 - 1000 lbs. of each available after the 2015 harvest as the "official" release. 

Both varieties were developed in hot, dry Southwest Oregon, and 2015 trials also took place in Wisconsin and New York. Spero expects both varieties to be broadly adapted, but anticipates ongoing trials in other regions.

Spero is continuing to work on three additional varieties of open-pollinated sweet corn: multi-colored Festivity, yellow-hued Ana Lee, and a bi-color variety yet to be named. All show promise, but need additional years of selection before they are ready for commercial release, he said.

“With some further refinement, open-pollinated corn finally begins to emerge as a real option for growers of sweet corn,” Spero said in his report. “This information may have particular value in poorer nations where old and inferior native varieties compete with patented GMO hybrids. This knowledge may help to empower rural people in poor nations to grow more and better food.”

Top Hat and Tuxana are pledged as open source under the Open Source Seed Initiative (OSSI), at www.osseeds.org.

Spero’s how-to plant breeding video is available on You Tube. For additional stories about Spero's research, click here, and here, and here, or visit our website and enter "sweet corn" in the search field.