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Hulled & Coated

Monday, January 30, 2017
filed under: Research and Development

Samples of XL confection in-shell sunflower seed, XL hulled kernels and three coated kernel samples. (Photo: NDSU Agricultural & Biosystems Engineering Dept. )
Samples of XL confection in-shell sunflower seed, XL hulled kernels and three coated kernel samples.
(Photo: NDSU Agricultural & Biosystems Engineering Dept. )
       Increased consumer demand—both domestic and export—for large in-shell confection sunflower seeds has grown dramatically over the past 15-20 years. A quarter century ago, in-shells constituted perhaps 40% of the seeds harvested from U.S. confection sunflower fields. That percentage grew to 75-80 by 2010 and is even higher today. 
       “The confection industry has changed dramatically over the years, with a clear focus now on in-shell products,” affirms Bob Majkrzak, president/CEO of Red River Commodities and past chairman of the National Sunflower Association Confection Committee. “New hybrids, coupled with growers who are capable of generating the best growing conditions, allow for the best value in the supply chain.”
       While confection growers have a clear economic incentive to produce as high a percentage of large seeds as possible, that endeavor is hardly without its challenges—one being the plantability of the larger new confection hybrids. 
      “The larger the planting seed, the trickier it is to plant,” Majkrzak points out.
      Results can take the form of more seed damage in the planter, less consistency in seed placement (and, correspondingly, less plant stand uniformity), as well as delayed and/or unsatisfactory plant germination/emergence. 
     “The top cause for limiting yield in confection sunflower is plant spacing,” Majkrzak says.  “If the seed could be more uniform, coupled with the use of new precision planters, the in-row spacing issue could be dramatically reduced.”
       Most production of hybrid confection planting seed occurs in California, with clean seed being sized into small, medium, large and extra large (XL) categories on a lot-by-lot basis. 
       “The extra large seed has not been usable by growers, for various reasons, such as the difficulty of planting and requiring near-perfect conditions to get the seedling out of the shell,” Majkrzak explains. “The extra large seed from the California production is sold as basic ‘commercial in-shell’ at a huge discount to the cost. But the kernel inside these extra large size seeds is absolutely perfect for growing.”
       That’s the background behind a current North Dakota State University research project partially funded by the National Sunflower Association. The project, led by NDSU ag engineer Dennis Wiesenborn, is based on the concept of planting hulled, coated hybrid confection seed rather than in-shell planting seed. The NDSU project, now in its fourth year, has focused on two primary objectives, as encouraged by the NSA Confection Committee: 
  1. finding effective ways of removing the hull without damaging the growth potential of the planting seed, and
  2. finding a coating that would allow for handling through the planter and provide good emergence. 
       Initial work focused on finding ways of hulling hybrid seed efficiently and without damaging the seed. One idea was to compress the seed in a transverse orientation to pop it open efficiently and with minimal damage to the kernel.  This was accomplished by inclining a roller mill at 45° and then feeding seed into the roll gap using a grooved feeding tray. The tray maintains seed orientation up to the roll gap and was produced at NDSU using a 3-D printer.
       The system is capable of releasing 75% of the kernel with three passes, achieving 85% intact kernel with kernel germination of 92%. However, gentle removal of the kernel pieces remains a challenge, and the process should be scaled up to accomplish a 40-acre field test in 2018.
       The first round of coating trials was in 2014/15. NDSU researchers Harjot Sidhu and Ewumbua Monono looked at kernels coated with four materials, respectively:  cellulose, lime, GroCoat® (a seed encrustment product from Seed Dynamics) and polymers.  Germination percentages ranged from 84 to 92%. However, the highest germination dropped to 84% after passage through the air seeder test stand, and corresponding seed singulation was only 79%.
       In 2016 the NDSU group further refined procedures to safely and effectively dehull XL planting seed and to test germination. Hulled kernels were coated by four different companies using eight types of coating materials (three types of polymer, cellulose, limestone, gypsum, zeolite and pumice). Buildup on the kernels ranged from 8 on up to 50%.  The NDSU team also developed two in-house methods of kernel coating.
       Taking 50 lbs of XL confection sunflower seed, the NDSU team produced 20 lbs of intact kernels for the above treatments. For 2017 field testing (and their anticipated seed volume needs for larger-scale field testing in 2018), Wiesenborn and his associates plan to use a Clipper Separator in collaboration with a newly developed concept for efficient, gentle hulling. They’ll also be collaborating with the Iowa State University Seed Laboratory as the project moves forward.
       How good was the germination rate for the various coated kernel products tested in 2016?  The respective germination rates were as follows: zeolite, 89%; lime, 86%; pumice, 86%; polymer A, 85%; polymer B, 81%; and kernels coated in-house with polymer C, just under 90%. By comparison, the germination rate for the XL in-shell seed averaged 85%.
       The NDSU ag engineers also gauged seed singulation by using a precision planting test stand equipped with a John Deere seed plate. One of the coating companies added talc to their polymer B-coated kernels, with a resulting singulation performance of >90%. Top singulation results from the other coated kernel samples (no talc) were: polymer A, 87%; cellulose, 80%; gypsum, 78%; zeolite, 77%; pumice, 77%. The tested XL in-shell seed produced a 68% singulation rate.
       “A test was later conducted with two lubricants (Bayer’s fluency agent and talc) to test their effect on plantability,” Wiesenborn notes. “Addition of these lubricants to the coated kernels improved the singulation while protecting the germination of the coated kernels inside the planter.” The use of a seed lubricant during the coating process will be researched further by the NDSU group.
       Field trials were conducted last season at Prosper, N.D., under the direction of Burton Johnson, NDSU professor of sunflower, minor and new crop production. Planting took place on June 7 and encompassed 15 treatments. Three coated treatments (34% lime buildup, 25% polymer B+talc and 18% polymer C applied in-house) had a live-seed emergence of 80-83%. That rate was similar to the planted “large” in-shell confection seed (at 83%) and slightly higher than the XL in-shell seed in the trial (79%).
       A primary objective in 2017 is to utilize a precision planter for field tests of the coated kernels. (A precision unit was not used in 2016). The NDSU team also plans to apply for a USDA grant for more-advanced testing of coated kernel feasibility, including shelf life.
         A successful outcome of this project on extra-large seeds will open up the possibility to extend this research to other sunflower seed sizes and even other crops.
— Don Lilleboe    
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