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Seeds of Success
Wednesday, January 6, 2016
filed under: Historical
Nearly 25 years ago, in the summer of 1991, I wrote and edited a second edition of Sunflower Handbook, an introductory guide to the U.S. sunflower industry, published by the National Sunflower Association. Among its chapters was one called “The Seeds of Success,” a short overview of hybrid development up to that point. I hope readers of The Sunflower will enjoy these excerpts from it. — Don Lilleboe
Peredovik was the leading oil sunflower variety grown by western Minnesota/ eastern North Dakota farmers during the latter 1960s. Like other commercial varieties, it was an open-pollinated type, meaning it required insects for pollination and did not produce particularly uniform plants — in terms of height, flowering date or maturity — across a field.
Hybrid seed was readily available for growers of certain other field crops such as corn and sorghum (milo). During the 1960s, scientists from the United States, Canada and several other nations were busily laying the groundwork for the hybridization of commercial sunflower. The puzzle finally came together around the turn of the decade with the discovery of cytoplasmic male sterility and genes for fertility restoration.
This discovery opened the door for the production of hybrid sunflower seed in a dependable and economical manner. The first sunflower hybrids were appearing in U.S. farmers’ fields as of 1972; by the latter ’70s virtually 100 percent of the nation’s sunflower acreage was planted to hybrid seed. The result was a substantial increase in yield, improved disease resistance, good self-compatibility (i.e., minimizing the need for pollination by insects) and uniformity of sunflower plant height, flowering date and maturity.
Parentage of the commercial oil sunflower hybrids of the 1970s was, in large part, based on the U.S. Department of Agriculture-developed hybrid 894. As the industry flagbearer, 894 served as the “hybrid to beat” for new oil-type varieties coming onto the marketplace during the ’70s and ’80s.
Today’s leading hybrids have moved beyond 894, both in performance and in possessing an expanded genetic base. While 894-type hybrids continue to perform fairly well, plant breeders generally agree that the top hybrids of the latter 1980s and early 1990s are quite different in parentage — and are superior to 894 in terms of yield, oil percentage, disease resistance and other desirable traits.
Several commercial seed companies, along with USDA, conduct extensive sunflower breeding programs in order to provide farmers with even better hybrids in the future. USDA geneticists focus on developing germplasm with improved traits in categories such as disease resistance, oil content and yield. Other USDA scientists are investigating the numerous wild sunflower species and what they may have to offer cultivated varieties in categories like disease resistance or drought tolerance. Promising germplasm is released to the private seed companies, whose breeders then evaluate the material and incorporate it into hybrids as they see fit.
Disease resistance is a never-ending challenge due to the continual evolvement of plant pathogens. Traditionally, four major diseases have affected U.S. sunflower: Verticillium wilt, downy mildew, rust and Sclerotinia. The first two have been largely controlled through the incorporation of resistant genes into commercial hybrids.
At the other extreme, Sclerotinia resistance has proven very elusive — due in large part to the disease’s complex nature and its various forms.
Most sunflower hybrids possess resistance to certain races of rust. New races develop from time to time, however, requiring ongoing efforts by breeders and plant pathologists to discover and incorporate resistance to these new races.
Like scientists in other areas of agriculture, sunflower breeders — both public and private — are beginning to utilize the techniques of biotechnology in their quest for hybrids which will produce better and be able to fend off stress caused by disease, insects or environmental influences such as drought.