In the Intermountain West, native plant communities are being lost because of exotic plant invasions, changing fire regimes, and increasing human population pressure and activities (Balch et al., 2013; Liu and Wimberly, 2015). The National Seed Strategy (Plant Conservation Alliance, 2015) and other recent federal directives emphasize the use of native species to assist the recovery of degraded public lands. Native shrubs and grasses have long been used for revegetation following wildfires and other disturbances. A current priority is the addition of a greater number of native forbs to revegetation plantings that are designed to conserve sage-grouse habitat, increase pollinator populations (Dumroese et al., 2015), and reestablish native communities that are diverse and resilient following wildfire. Increasing the use of Eriogonum heracleoides Nutt. and E. umbellatum Torr. as well as other common buckwheat species necessitates development of cultural practices required for increase of their seed in agricultural settings, as wildland collections are expensive and generally inadequate to meet revegetation needs. For most forb species where seeds are in demand for restoration use in the Intermountain West, guidelines for seed production practices are not available (Cane, 2008; Shaw and Jensen, 2014).
Eriogonum heracleoides (parsnipflower or Wyeth buckwheat) and E. umbellatum (sulphur-flower buckwheat) of the Polygonaceae family are low-growing, taprooted subshrubs that are widespread in the Rocky Mountains and Intermountain West with ivory and yellow flowers, respectively (Reveal, 2012). Both species are mat or clump-forming and produce upright flowering stems that support umbrella-like clusters of flowers. They commonly occur scattered among other vegetation on dry, exposed sites with well-drained soils and are common in rocky and sandy areas. E. heracleoides occurs from the sagebrush (Artemisia spp. L.) zone through open areas in aspen (Populus tremuloides Michx.) and other forested communities, whereas E. umbellatum grows in communities from the sagebrush to the subalpine zone (Reveal, 2012; Welsh et al., 1987).
Eriogonum spp. are drought hardy and long-lived. Both species are recommended for plantings to provide pollinator habitat (Ogle et al., 2011). E. umbellatum provides food and habitat for sage-grouse (Bunnell et al., 2004; Pyle, 1993). Because of their low palatability, most perennial Eriogonum spp. are not considered valuable forage plants for wildlife or domestic livestock, but they are used to some extent in spring and fall when other forage may not be available (USDA Forest Service, 1937). Sheep seek out the flower clusters. Eriogonum spp. are useful for low-maintenance landscaping, xeriscaping, and rock garden plantings in urban areas, recreation sites, and along roadsides (Dyer et al., 2005; Parris et al., 2010; Tilley et al., 2007; Young-Mathews, 2012). They are attractive year-around, require little water and are easily maintained. Plants are semievergreen, and flower in early to midsummer after many other natives have completed their flowering cycle. The flowers are long-lasting and remain colorful after drying on the plants (Meyer, 2008).
Where adapted, Eriogonum spp. can add diversity to native seedings and are particularly valuable because of their ability to establish on disturbed sites resulting from activities including road construction or energy development. Once established, they can provide erosion control due to their mat-forming habit and natural spread. They may also serve as nurse plants that enhance establishment of later arriving species (Meyer, 2008).
Practices that increase the reliability of seed production are needed to reduce grower risk. Although E. heracleoides and E. umbellatum generally occur in areas receiving low precipitation, recommendations for optimal amounts and timing of irrigation for individual species are needed to improve the reliability of seed production because seed production can be very low in dry years. Research has described the seed yield responses of five species of Intermountain West perennial forbs of the genus Lomatium to irrigation and seasonal precipitation (Shock et al., 2016). Sprinkler or furrow irrigation encourages weeds and the spread of fungal pathogens. Subsurface drip irrigation reduces these problems by decreasing surface soil wetting. Reduction of weeds is a critical concern when growing native forbs as herbicides have not been approved for use with these species.
We report the effects of three low rates of subsurface drip irrigation on seed yield of E. heracleoides and E. umbellatum, and how these seed yield responses to irrigation are affected by precipitation. Optimum irrigation for each species was based on the amount of irrigation and seasonal precipitation during each year of production. Seed yield response of E. umbellatum to irrigation has been reported for the earlier years of this trial (Shock et al., 2015). Because seed yield can vary between years due to harsh weather, differences in pollination, and many other factors, we report also the effects of the low rates of subsurface drip irrigation on the relative seed yield calculated as the percentage of the yield of the highest yielding treatment for each species for each year.
AgriMet 2016 Bureau of Reclamation Pacific Northwest Region. 2 June 2017. <http://www.usbr.gov/pn/agrimet/>
Balch, J.K., Bradley, B.A., D’Antonio, C.M. & Gómez-Dans, J. 2013 Introduced annual grass increases regional fire activity across the arid western USA (1980–2009) Glob. Change Biol. 19 173 183
Breen, A.N. & Richards, J.H. 2008 Irrigation and fertilization effects on seed number, size, germination and seedling growth: Implications for desert shrub establishment Oecologia 157 13 19
Bunnell, K., Flinders, T., Mitchell, D.L. & Warder, J.H. 2004 Occupied and unoccupied sage grouse habitat in Strawberry Valley, Utah J. Range Mgt. 57 524 531
Cane, J.H. 2008 Pollinating bees crucial to farming wildflower seed for U.S. habitat restoration, p. 48–64. In: R. James and T.L. Pitts-Singer (eds.). Bees in agricultural ecosystems. Oxford University Press, New York, NY
Dumroese, R.K., Luna, T., Richardson, B.A., Kilkenny, F.F. & Runyon, J.B. 2015 Conserving and restoring habitat for greater sage-grouse and other sagebrush-obligate wildlife: The crucial link of forbs and sagebrush diversity Native Plants J. 16 276 299
Dyer, D., O’Beck, R. & Young-Mathews, A. 2005 Plant guide for sulphur-flower buckwheat (Eriogonum umbellatum). USDA Natural Resources Conservation Service, Lockeford, CA. 4 p. 2 June 2017. <http://plants.usda.gov/plantguide/pdf/pg_erum.pdf>
Feibert, E.B.G. & Shock, C.C. 2016 2015 weather report, p. 1–10. In: C.C. Shock (ed.). Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2015, Department of Crop and Soil Science Ext/CrS 156. 16 July 2017. <http://www.cropinfo.net/pdf/ar/2015/2015-003-WeatherReport.pdf>
Liu, Z. & Wimberly, M.C. 2015 Direct and indirect effects of climate change on projected future fire regimes in the western United States Sci. Total Environ. 542 65 75
Meyer, S. 2008 Eriogonum Michx.: Wild-buckwheat, buckwheatbrush, p. 499–503. In: F.T. Bonner and R.P. Karrfalt (eds.). Agriculture handbook No. 747. USDA Forest Service, Washington, DC. 2 June 2017. <https://www.fs.fed.us/rm/pubs_other/wo_AgricHandbook727/wo_AgricHandbook727_499_503.pdf>
Ogle, D., Pavek, P., Fleenor, R., Stannard, M., Dring, T., Cane, J., Fullen, K., St. John, L. & Tilley, D. 2011 Plants for pollinators in the Inland Northwest. TN Plant Materials No. 2B. U.S. Department of Agriculture, Natural Resources Conservation Service, Boise, ID. 65 p
Parris, C., Shock, C.C., Feibert, E. & Shaw, N. 2010 Sulphur-flower buckwheat: Eriogonum umbellatum (ERUM). Sustainable agriculture techniques: Native plant seed production. EM 9017. Oregon State University Extension Service, Corvallis, OR. 4 p. 2 June 2017. <http://www.cropinfo.net/pdf/extension/em9017-SulphurFlowerBuckwheat.pdf>
Petersen, J.L. & Ueckert, D.J. 2005 Fourwing saltbush seed yield and quality: Irrigation, fertilization, and ecotype effects Rangeland Ecol. Manag. 58 299 307
Plant Conservation Alliance 2015 National seed strategy for rehabilitation and restoration 2015–2020. BLM/WO/GI-15/012+7400. 50 p. 2 June 2017. <https://www.fs.fed.us/wildflowers/Native_Plant_Materials/documents/SeedStrategy081215.pdf>
Pyle, W.H. 1993 Response of brood-rearing habitat of sage grouse to prescribed burning in Oregon. Oregon State Univ., Corvallis, MS Thesis
Reveal, J.L. 2012 Polygonaceae, the Knotweed Family, p. 196–386. In: N.H. Holmgren, P.K. Holmgren, J.L. Reveal, and Collaborators. Intermountain flora vascular plants of the Intermountain West, U.S.A. Volume Two, part A Subclasses Magnolidae-Caryophyllidae. The New York Botanic Gardens, Bronx, NY
Roundy, B.A., Heydari, H., Smith, C.W.S.E. & Pater, B.M.M. 2001 Summer establishment of Sonoran Desert species for revegetation of abandoned farmland using line source sprinkler irrigation Arid Land Res. Mgt. 15 23 39
Shaw, N.L. & Jensen, S. 2014 The challenge of using native plant materials for sagebrush steppe restoration in the Great Basin, USA, p. 141–159. In: K. Kiehl, A. Kirmer, N.L. Shaw, and S. Tischew (eds.). Guidelines for native seed production and grassland restoration. Cambridge Scholars, Newcastle upon Tyne, UK
Shock, C.C., Feibert, E.B.G., Rivera, A., Saunders, L.D., Shaw, N.L. & Kilkenny, F.F. 2016 Irrigation requirements for seed production of five Lomatium species in a semi-arid environment HortScience 51 1270 1277
Shock, C.C., Feibert, E.B.G., Saunders, L.D., Parris, C.A. & Shaw, N.L. 2011 Evaluation of herbicides for weed control in forb seed production. Malheur Experiment Station annual report 2010, Corvallis, OR, Oregon State Univ. Agr. Expt. Sta. Ext/CrS 132:186–198
Shock, C.C., Feibert, E.B.G., Shaw, N.L., Shock, M.P. & Saunders, L.D. 2015 Irrigation to enhance native seed production for Great Basin restoration Nat. Areas J. 35 1 74 82
Tilley, D., Ogle, D. & St. John, L. 2007 Parsnipflower buckwheat: Eriogonum heracleoides Nutt. USDA Natural Resources Conservation Service, Aberdeen, ID. 3 p. 2 June 2017. <http://www.plant-materials.nrcs.usda.gov/pubs/idpmcpg7076.pdf>
USDA Forest Service 1937 Range plant handbook. USDA Forest Service, Washington, DC
USDA/NRCS 2007 Wyeth Buckwheat Eriogonum heracleoides Nutt. plant guide. 2 June 2017. < https://plants.usda.gov/plantguide/pdf/pg_erhe2.pdf>
Welsh S.L., Atwood N.D., Higgins L.C. & Goodrich S. 1987 A Utah flora. Great Basin Naturalist Memoir 9. Brigham Young University, Provo, UT
Young-Mathews, A. 2012 Plant fact sheet for sulphur-flower buckwheat (Eriogonum umbellatum). USDA Natural Resources Conservation Service, Corvallis, OR. 2 p. 2 June 2017. <http://plants.usda.gov/factsheet/pdf/fs_erum.pdf>