Wheat varieties which contain complementary genetic traits but similar phenotypic traits were blended together in equal proportions and compared to the variety components grown separately. Six blend combinations were tested in 50 trials over a three-year period. All six blends were superior to the average of their components when averaged over the 50 trials. Nearly 50% more individual locations/blend combinations showed increases than decreases of blends vs. components. Yield increases were up to 1.7 bushels per acre for the best blend.
Organic and low input production of winter wheat is dependent on varieties that are adapted to a given region, that maintain high end-use quality, resist diseases and insects, and have a high yield level. Most wheat varieties cannot meet all these requirements of pest resistance, yield potential, and end-use quality. A highly successful winter wheat variety has its usage rapidly expand over a large geographic area of the wheat producing part of the Great Plains, dramatically reducing bio-diversity. When a variety begins to occupy over 20% of the area from Oklahoma to South Dakota, the resistance to diseases and insects quickly breaks down. This makes the most successful varieties more susceptible than less successful varieties. Thus, the yield stability is decreased across the whole region. The quick demise of a variety causes more strain on the wheat production system because of the time it takes to get a new variety with new sources of resistance into new varieties. Unfortunately, there is a lag of several years before enough seed of a new variety can be developed. Winter wheat production would be more sustainable and profitable if the most successful varieties could be sustained at a high yield level for more years. Several area farmers have asked if blends could be used to maintain bio-diversity and maintain high yield potential. This presents several beneficial effects. It presents the attacking organisms with a more diverse target, which makes it more difficult for them to mutate and build up a high number of tolerant types. Blends also give the opportunity for varieties to complement each other making them more stable from one year to the next. It may be possible to modify the blends by using a widely adapted variety as a base and adding locally adapted varieties which would change from one area to the next.
Farmers in China have used blends of rice for many years. A study of this practice by scientists shows that blends of rice have stabilized yields by eliminating disease and insect catastrophes. They have also eliminated the use of fungicides while maintaining yields. Blends have also been used successfully in peanut in Florida and soybean in India. Wheat blends have been used in Tunisia. Kansas State University has tested winter wheat blends for several years. Our Nebraska variety tests have only included pure lines and many times the highest yielding variety one year is not the highest yielding the next year. However, usually the top three varieties continue to perform in the top three the next year. Thus, by using blends, we can gain make better use of the top yielding varieties.
Much research and fine tuning is necessary to obtain the greatest advantage from blends. From a theoretical approach, a number of blends could be proposed which take advantage of genetic diversity while maintaining similar maturity and height characteristics. Another advantage can be traced to end-use quality. Since nearly all varieties have some quality weaknesses, the use of blends could improve the overall quality of the crop. Once several blends have been made based on the theoretical advantages, they would need to be field tested. In order to determine the potential for blends, tests need to be conducted over a large number of farms for three years. The blends would also need to be compared with a large number of the best varieties for each part of the region. All of the blends would consist of hard red winter wheat so the blends would not encounter marketing problems for the buyers of the grain.
The first goal was to publicize the concept of wheat variety blends, demonstrate the feasibility of blends to compete with pure lines, and learn about the behavior of various blends compared to their pure line components.
The second goal was to help producers utilize wheat blends to increase the bio-diversity of their farms and the region. Annual survey of wheat varieties planted will be used to monitor this. The target area is the wheat production region of Nebraska (1.5 million acres).
The third goal was to have acceptance of variety blends on producer’s farms. Acceptance could change the emphasis of the wheat breeding program and improve economic conditions for rural communities as well as individual farmers.
We included farmers, seedsmen, wheat breeders, and variety testers dealing with winter wheat to formulate ten blends of different adapted varieties having different sources of disease and insect resistance. We used height, maturity and quality characteristics in formulating these blends. These blends included from two to four varieties. Once formulated, these blends were tested on at least 15 producer fields each year using their management practices. The blends were compared with their pure line components. During the growing season, these blends were monitored for disease and insect problems by the individual producers and University of Nebraska specialists. Tours were held at each location each year to discuss the blends and gather input from local producers on potential blends for future trials. Finally, harvest and agronomic data were collected and analyzed. The results of the first year study were used to refine recommendations regarding what blends test in subsequent years. The accumulation of data was used to recommend blends and the advantages which can be expected from their use. The farmers and seedsmen themselves were involved in the education on the success or failures of the blends.
Field days were held at most of the 50 farm and research station locations over the three year period. Over 1000 farmers and seedsmen were in attendance at these meetings to observe the performance of wheat blends in the field. During these meetings, the concept of blends was demonstrated and explained to those in attendance. Grain yield data obtained at harvest were summarized in each year in E.C. 103, Fall Seed Guide. Over 60,000 copies of the Fall Seed Guide have been distributed to farmers and seedsmen during the three-year period.
At the end of the first year, the results were used to change several of the blends. All of the four-component blends were discontinued and two white wheat blends using two components were added. The blend of tall wheat varieties was removed from the irrigated sites due to lodging problems.
The combined analysis for all three years consisted of six blends which were unchanged over the three years. Analysis shows that all six blends yielded .86 bushels per acre better than the average of their components when averaged across the 50 trials. The best performing blend included the varieties ‘Millennium’, ‘Wahoo’, and ‘Halt’. Thirty-seven out of 49 locations showed improved yield of the blend over it’s components with an average increase of 1.6 bushels per acre. The second best blend included the varieties ‘Jagalene’, ‘Wesley’, and ‘2137′. It had an increase in yield of 1.3 bu/a over the average of its components and 34 out of 50 locations showed the blend yielding more grain than the average of its components.
Wheat variety blends were planted in replicated yield trials across Nebraska. Through 50 field day programs and winter meetings across the state, the concept of wheat blends was publicized to more than 1500 producers and indirectly to many others through media coverage of the events. Data obtained from harvested plots across the state gave us a good indication that the use of blends would increase wheat yields. Discussions were also held with members of the Nebraska Crop Improvement Association. Discussions with seedsmen throughout the state are used to promote the idea of wheat blends.
The cost of creating and planting blends is nearly the same as planting the same varieties in pure stands. Many seedsmen in the state have indicated a willingness and ability to formulate blends for farmers. Based on our tests, there could be more than 1 bushel per acre increase in grain yield due to the use of blends with little added input. The use of blends would help producers with a small acreage of wheat have complementary varieties without keeping varieties separate.
Interest among farmers and seedsmen continues to be high, but very few acres of wheat blends have been planted in Nebraska to date. One reason may be that the early adopters with larger wheat acreage have less need for it than farmers with smaller acreage.
Educational & Outreach Activities
The concept of winter wheat blends has been presented to hundreds of farmers and seedsmen through meetings, field days, Extension Circulars, and a web site. The Fall Seed Guide, EC103, is distributed to over 20,000 producers each year and contains information regarding the performance of blends. The variety testing web site, http://varietytest.unl.edu/winterwheat.html, contains the information regarding the performance of blends. This web site generates thousands of ‘hits’ each year. Plans are still in progress to publish a research paper from this data.
Neway Mengistu, P. Stephen Baenziger,* L. A. Nelson, K. M. Eskridge, R. N. Klein, D. D. Baltensperger, and R. W. Elmore. "Grain Yield Performance and Stability of Cultivar Blends vs. Component Cultivars of Hard Winter Wheat in Nebraska." Crop Science, Vol. 50, March-April 2010.
Areas needing additional study
The biggest challenge appears to be having farmers accept blends as a way to improve their wheat yield.
Questions continue to arise regarding how blends are affected by seed laws.
There will be need for continual updating of blend data as new varieties of wheat are introduced.