Tinsley, S. 2012. An evaluation of perennial wheat and intermediate wheatgrass as dual-purpose, forage-grain crops under organic management. Thesis, Michigan State University, East Lansing, MI USA.
The adoption of perennial grain crops presents farmers with many environmental, economic, and agronomic opportunities and risks. If crops such as perennial wheat (Triticum aestivum x Thinopyrum elongatum; Pwheat) and intermediate wheatgrass (Thinopyrum intermedium IWG), two novel perennial grain species, can thrive as dual-purpose forage-grain crops, many of these risks will be alleviated. Annual winter wheat (Triticum aestivum L.) is a successful dual-purpose forage-grain crop and IWG is a highly successful perennial forage grass in the southern Great Plains region. Wheat breeding programs at Washington State University (WSU) and The Land Institute (TLI) have developed lines of Pwheat by crossbreeding these two species and have also bred IWG for improved levels of grain production, while maintaining forage yield.
To evaluate the potential of these novel species for use as dual-purpose forage-grain crops in organic systems in Michigan, a field experiment to determine robustness of plant growth and perennial regrowth, as well as quality and quantity of harvested grain and forage for two cutting regimes, was conducted from fall 2010 to fall 2012 in southwest Michigan at Kellogg Biological Station (KBS). Our data indicate that Pwheat produces higher grain yields than IWG (Pwheat[approximate]238.70 g/m 2 , IWG[approximate]103.55 g/m2 ), but is less able to initiate late-season regrowth, and thus maintain perenniality (Pwheat[approximate]59% regrowth, IWG[approximate]100% regrowth). In addition, Pwheat tends to produce lower quality forage in smaller quantities than IWG (Pwheat[approximate]560.71 g/m 2 , IWG[approximate]797.72 g/m2 ), especially after the first year of growth (year 2 Pwheat[approximate]391.23 g/m2 , year 2 IWG[approximate]956.20 g/m2 ). Spring forage cutting generally did not have a long-term effect on plant growth or production. Overall, species choice must depend on the goals of a specific farm, since there are unique benefits for each species; namely, IWG shows greater perenniality and greater potential for production of high-quality forage, while Pwheat shows greater potential for grain production.
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