P ropag at ion a nd Agronomic Seed Incre a se of N at i v e Sedge s (Car ex ) Greg Houseal, Tallgrass Prairie Center, University of Northern Iowa, Cedar Falls, Iowa 50614-0294, gregory.houseal@uni. edu

Abstract: Plant materials of species native to wet prairie and sedge meadows in Iowa, particularly sedge (Carex) species, are in demand for restoration. Commercially available seed in quantity would facilitate restoration, potentially increasing the efficiency and scale of restorations. An agronomic technique using plastic film (mulch) and drip irrigation (t-tape), called plasticulture, was used for establishment and increase of several native Carex species. Seed collections from remnant populations were propagated as greenhouse plugs and transplanted into plastic film-covered beds and irrigated with drip irrigation. Species in trial production beds include yellow fox sedge (Carex annectens), Bebb’s sedge (C. bebbii), plains oval sedge (C. brevior), Buxbaum’s C. (buxbaumii), crested sedge (C. cristatella), troublesome sedge C. (molesta), woolly sedge (C. pellita), running marsh sedge (C. sartwellii), broom sedge (C. tribuloides), and fox sedge (C. vulpinoidea). Initial results using these techniques demonstrate a small harvestable seed crop is possible the first growing season for some species. Second-year estimated bulk seed yields ranged from a low of 33 kg/ha (29 lbs/ac) for C. cristatella to a high of 498 kg/ha (429 lbs/ac) for C. vulpinoidea, while remaining species ranged from 194 to 436kg/ha (168 to 376 lbs/ac). All species were cleaned to purities exceeding 90%. Potential market value, in terms of dollar value of pure live seed per unit production area ($PLS/ unit area), was greatest for C. tribuloides, C. annectens, and C. vulpinoidea, at $43.27/m2 (3.89/ft2), $20.93/m2 (1.88/ft2), and $11.18/m2 (1.01/ft2), respectively. Key Words: Carex seed production, drip irrigation, perigynium, plasticulture, stratification, transplant Introduction   Carex species occupy an array of habitats from deepwater marshes to open woodlands, to dry, gravelly blufftop and ridge prairies. They are cool-season grasslike (graminoid) plants, and may comprise as much as a quarter of the aboveground biomass in tallgrass prairies (Coppedge et al. 1998). Carex species are the dominant vegetation in sedge meadow communities, yet are seldom included or are underutilized in seed mixes for prairie and wetland restorations. One reason for this is that commercial

sources and quantities of Carex seed are limited. Challenges to Carex production include 1) accurate species identification, 2) adequate germination of wildland seed collections, and 3) developing efficient methods of commercial production (Houseal and Smith 2010).   Currently, 120 species of Carex are known to occur in Iowa (Norris and Zager 2008). Approximately 53 species might be considered wet-mesic to dry-mesic prairie species, with several additional species predominately associated with wetlands. The main objectives of this project were to 1) evaluate plasticulture techniques for establishment of seedling plugs, and 2) develop seed production plots of several native Carex species suitable for prairie and wetland restoration.

Figure 1. In Carex, the seed is enclosed in a single-seeded fruit called an achene, which is enclosed in a sac-like structure called a perigynium.

Materials and Methods Collection of Seed   In Carex, the seed is in a single-seeded fruit called an achene, which is enclosed by a sac-like membranous structure

Table 1. Carex species transplanted into plasticulture beds. For a description of wetland indicator regions and categories see USDA-NRCS PLANTS database http://plants.usda.gov/wetinfo.html#regions. Region 3 is the North Central Region, USA (IA, IL, IN, MI, MN, MO, WI). Scientific Name

Common Name

Carex annectens (E.P. Bicknell) E.P. Bicknell Carex bebbii Olney ex Fernald Carex bicknellii Britton Carex brevior (Dewey) Mackenzie Carex buxbaumii Wahlenb. Carex cristatella Britton Carex molesta Mackenzie ex Bright Carex pellita Muhl. ex Willd Carex sartwellii Dewey Carex tribuloides Wahlenb. Carex vulpinoidea Michx.

Yellow fox sedge Bebb’s sedge Bicknell’s or Prairie sedge Plains oval sedge Buxbaum’s sedge Crested sedge Troublesome sedge Woolly sedge Sartwell’s or Running marsh sedge Blunt broom sedge Common fox sedge

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Wetland Indicator Status Region 3 FACW OBL FACFAC OBL FACW+ FAC OBL OBL FACW+ OBL

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called a perigynium. These perigynia are arranged in spikes of various configurations, depending on species (Figure 1). Seeds (here after referred to as perigynia) were thus collected by stripping perigynia (or entire spikes of perigynia) from individual plants from populations of selected species (Table 1). Collections were made predominately in late June through mid July of 2008 from remnant prairies in east central, north central, and northeastern Iowa. Specimen plants were collected for each species at each site, and perigynia were randomly collected from several individual clumps from throughout the population. Species field identification was checked with a hand lens, and later confirmed in the lab under a dissecting microscope. Because the ultimate goal was to propagate seedlings, all species were collected when perigynia were mature. This facilitated identification since sedges are most easily identified when fruits are ripe (Hipp 2008). Hybrid or questionable forms were avoided. Perigynia were air-dried (ambient, forced-air) for two weeks, and hand-screened to remove sticks, leaves, and larger particles, and then aspirated with a South Dakota seed blower to remove pistillate scales and perigynia with aborted or empty (nonviable) achenes.

population and watered with an overhead mist system to avoid seed displacement until germination occurred. Germination began within 2 weeks after sowing, and occurred during a protracted period over the next several weeks. Seedling growth in Carex species is generally rapid after germination, and seedlings were grown for approximately two months with natural light in a greenhouse with an ambient temperature of 78°F (25.5°C) (Figure 2). Plastictulture Production Beds  Seed production beds were set up using a system known as plasticulture, adapted for Carex production (Houseal 2010). Plasticulture has been used in the vegetable industry since the early 1960s (Sweat 2007). Black plastic film (mulch, Pliant USA, 1.0 mil) covers the bed to provide weed control, Table 2. Harvest dates, plot size, bulk yield and estimated seed yield/ unit area from selected Carex species, second full growing season after transplanting. Species C. annectens C. bebbii

Greenhouse Propagation   Three factors generally favor germination in Carex. These are 1) cold moist stratification, 2) alternating soil temperature (50°F daytime/70°F nighttime) after sowing, and 3) perigynium exposure to light after sowing (Schütz and Rave 1999, Kettenring et al. 2006, Kettenring and Galatowitsch 2007). Achenes were not removed from perigynia, and were coldstratified intact in moist, sterile sand for 4 weeks at 40°F (4°C). Since light generally enhances sedge germination (Schütz and Rave 1999, Kettenring et al. 2006), perigynia were sown very shallowly at 3mm (1/8 in) depth into potting medium in 70-count trays, 7.62 cm (3 in) deep in February and March 2009. One or two trays (70-140 cells) were seeded for each

Figure 2. Crested sedge (C. cristatella) seedlings about 3 weeks after germination, growing in Ray Leach fir-cell Cone-tainers (Stuewe and Sons, Tangent, OR; http://www.stuewe.com/).

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Harvest Plot size Bulk Yield Yield/Unit Area Date m2 (ft2) kg (lbs) kg/ha(lbs/ac) 1 July 56 (624) 2.2 (4.7) 383 (330) 1 July

42 (464)

1.1 (2.5)

267 (230)

C. bicknellii

23 June

9 (104)

0.2 (0.4)

194 (168)

C. brevior

23 June

65 (726)

2.1 (4.5)

315 (272)

C. cristatella

20 July

71 (792)

0.2 (0.5)

33 (29)

C. molesta

29 June

36 (400)

1.1 (2.5)

310 (267)

C. tribuloides

24 June

76 (844)

3.3 (7.3)

436 (376)

C. vulpinoidea

16 July

59 (660)

2.9 (6.5)

498 (429)

and drip irrigation tape (t-tape, 10 mil, 30 cm drip spacing) is installed beneath the film to provide supplemental moisture (and fertilizer, if needed). The plastic mulch enhances soil warming and moisture and nutrient retention, and effectively lengthens the growing season, promotes establishment, and increases plant size and potential yields (Lamont 2004). Plasticulture beds were formed at ground level (as opposed

Figure 3. Transplanting two-month-old Carex seedling plugs (inset) into plasticulture beds in early spring 2009.

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to raised beds) to facilitate combine harvesting. Total area for seed production beds of each species is shown in Table 2.  Seed production beds were prepared by cultivation and rototillage so that no coarse stubble or stalks were present that could puncture plastic mulch film during installation. Two-month-old seedlings were transplanted at 20-cm (8in) intervals into plastic film mulch in late April and early May 2009 (Figure 3). Adequate soil moisture and reliable rains at this time of year and cool temperatures favor rapid establishment and growth of sedges. The last frostfree date for the area is approximately May 15. Sedges are generally frost tolerant, but transplanting was timed when the weather forecast predicted mild nighttime temperatures over the next several days. Weeds were controlled by hand

Figure 4. Combining lodged Carex seed heads with Hege 125B plot combine and resulting bagged material (inset).

pulling from the around base of transplanted seedlings within beds. The area between the beds was cultivated with a small, tractor-mounted 1.52 m (5 ft.) rototiller, so 1.83 m (6 ft.) spacing was left between the plastic mulchcovered beds. Harvesting Seed

Figure 5. Cleaning perigynia (inset) with Westrup LA-LS laboratory airscreen cleaner.

 A Hege 125B 1978 model plot combine was used to harvest selected species on the dates indicated in Table 2 (Figure 4). Harvested material was hand screened through 6.5 mm (½ in) and 13 mm (¼ in) hardware cloth to remove large particles, stems, and leaves and make the material more flowable. Material was then cleaned with a Westrup 3-screen air-screen cleaner (LA-LS Westrup Laboratory air screen cleaner) and submitted for seed test (Figure 5). Results and Discussion  Survival of transplanted Carex plugs was essentially 100 percent, and all plots were well established by mid-summer of the first growing season. All species established readily and grew rapidly throughout the spring, mostly remaining vegetative the first growing season with some exceptions. The vigorous rhizomatous spread of some species (e.g., Carex pellita, C. sartwellii, and C. buxbaumii) required opening up plastic mulch around the base of plants to accommodate new tiller growth. Plastic was removed from the C. pellita plot later in the season to accommodate vigorous tillering; drip tape was left in place for irrigation. Plastic mulch around clump-forming (caespitose) species was left intact.   Flowering and seed set were delayed the first season, if it occurred at all, relative to mature plants (second-year and beyond). This is normal for first-year transplants of many perennial species. Species that set seed the first growing season in the plasticulture beds included Carex bebbii, C. tribuloides, C. brevior, C. molesta, C. annectens, and C. vulpinoidea. The obligate wetland species C. bebbii produced enough seeds the first season to be combine harvested. This species produced an estimated 82.3 kg/ha (73.5 lbs/ac) of seed compared to 267 kg/ ha (230 lbs/ac) in year two. All species flowered and set fruit in year two. The highly rhizomatous species Carex pellita and C. sartwellii, and to some extent C. buxbaumii, had very limited flowering and seed production, and were simply hand harvested (data not shown). It was difficult to find quantities of seed of these species in the original native stands, as well, presumably because their primary mode of reproduction is vegetative (clonal spread) and not via seed. However, C. sartwellii growing in a pot in the greenhouse flowered prolifically, suggesting that resource limitation (stress) may enhance flowering, at least in this species.  Lodging of seed heads of plants growing along the edge of the beds onto the ground was an issue with several species of Carex, notably C. bebbii, C. brevior, C. molesta, and C. tribuloides, making combining difficult and resulting in lost seed. An attempt was made to lift lodged plants with a pitchfork, back toward the center of bed onto supporting vegetation, a week or so before seed shatter to facilitate combining, which mitigated seed loss to some extent. Lodging was not an issue with C. annectens, C. bicknellii, and C. vulpinoidea (Figure 6). Our experience has been that over-growing and lodging of shoots is not uncommon in native perennials when they are grown in a production setting, essentially released from competition

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Figure 6. Carex production beds in late June of second growing season, established from plugs transplanted previous spring. Yellow fox sedge (C. annectens, left) and brown fox sedge (C. vulpinoidea, right), remain upright, facilitating combine harvesting.

for nutrients and light compared to the highly competitive environment they are adapted to in complex native plant communities. C. cristatella grew so aggressively within the bed that a heavy thatch of first-year vegetation formed a mat, suppressing early season growth and possibly seed production in year two. Fall or early spring fire may be beneficial (by removing thatch) for increasing seed production of this species in particular, and of Carex species in general. Lodging may lessen in coming years as plants fully occupy available rootspace and thus have less-vigorous shoot growth, but seed production will likely decline, as well.  Estimated seed yields for most Carex species ranged from 194 kg/ha to 436kg/ha (168 lbs/ac to 376 lbs/ac), with a low of 33 kg/ha (29 lbs/acre) for C. cristatella and a high of 498 kg/ha (429 lbs/ac) Table 3. Estimated market value per unit area of seed harvest (2010) based on PLS yield for each Carex spp. Market Price* Seed Count* $PLS/unit area Species ($/PLS#) /g (/oz) $/m2 ($/ft2) C. annectens $300 3,175 (90,000) $20.93 (1.88) C. bebbii $150 1,199 (34,000) $ 7.56 (0.68) C. bicknellii $150 600 (17,000) $ 5.25 (0.47) C. brevior $150 1,023 (29,000) $ 9.37 (0.84) C. cristatella $450 2,046 (58,000) $ 2.36 (0.21) C. molesta Not commercially available 4,233 C. tribuloides $600 $43.27 (3.89) (120,000) 3,527 C. vulpinoidea $120 $11.18 (1.01) (100,000) *Prairie Moon Nursery, Winona, MN catalog price, 2010

for C. vulpinoidea (Table 2). Seed counts for these species range from 600-4233 seeds/g (17,000-120,000 seeds/oz) (Table 3). Again, issues with lodging of seed heads probably reduced recoverable seed yields of species mentioned previously. Seed yield of C. cristatella in production bed was surprisingly low, given its 202

apparent abundant seed production in native stands. Vigorous vegetative growth and complete colonization of the production bed during C. cristatella first growing season may have reduced flowering and seed production the second year. Transplanting this species at a lower density (greater spacing between and within rows) may improve seed production.   Harvested perigynia were screened and aspirated to high purity and submitted to a certified seed-testing lab for testing for percent purity and viability (tetrazolium or TZ test) (Table 4). High purities are obtainable by keeping production stands free from non-crop species (e.g., weeds as well as other Carex species), and by proper and thorough cleaning. High viability is a function of harvesting perigynia at maturity and proper aspiration to remove any light (unfilled) seed. Summary   The versatility of the plasticulture system provides efficient irrigation minimizes weedy competition during establishment, and shows great potential for seed production of native Carex species. Challenges with plasticulture include the cost of specialized equipment and removal and disposal or recycling of plastic mulch at the end of Table 4. Seed test results from selected Carex species second full growing season after transplanting Species

Purity (%)

TZ (%)

PLS (%)

C. annectens

98.5

84

82.8

C. bebbii

97.5

88

85.8

C. bicknellii

94.3

87

81.8

C. brevior

99.5

90

90.0

C. cristatella

94.9

76

72.2

C. molesta

98.8

84

83.0

C. tribuloides

96.9

76

75.3

C. vulpinoidea

99.5

86

85.1

its productive bed life. Equipment costs may be nominal compared to the cost of tractors, combine harvesters, and specialized seed-processing equipment (Houseal 2010). Carrying plastic mulch beds over for two and three growing seasons for the benefits of weed suppression and nutrient and water retention is possible. Using prescribed fire as a management tool would not be advisable unless irrigation t-tape can be placed well beneath soil surface to avoid damage.  Estimated yields for Carex species overall were in a range that could be economically viable for commercial seed production if market demand is in place (Table 4). Carex vulpinoidea is already available in the native seed trade in the Midwest, presumably because it is in demand and profitable. It is fairly easy to identify and propagate, and seed is easy to harvest and

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clean. Our work shows that other Carex species (C. annectens, C. bebbii, C. brevior, C. molesta, C. tribuloides) can be similarly productive in cultivation, and may be equally or more profitable, given their current higher market value (e.g., C. annectens, C. tribuloides), if markets develop for these species.  Our work also indicates that it is possible to collect and propagate Carex as individual species if proper field and lab techniques are used to avoid cross-contamination with similar species. We will continue to assess yields, stand life, and weed pressure in agronomic production of these and additional Carex species to determine which are practical for agronomic seed production using this system.

Sweat, M. 2007. Plasticulture technology for vegetable production. North Florida Research and Education Center, Suwanee Valley. At http://nfrec-sv.ifas.ufl.edu/ mulch.htm (accessed 10 Sep 2009). USDA Natural Resources Conservation Service. 2010. The PLANTS database. At http://plants.usda.gov.

Literature Cited Coppedge, B. R., D. M. Leslie Jr. and J. H. Shaw. 1998. Botanical composition of bison diets on tallgrass prairie in Oklahoma. Journal of Range Management. 51:379-382. Eilers, L. J. and D. M. Roosa. 1994. The vascular plants of Iowa: An annotated checklist and natural history. University of Iowa Press, Iowa City. Hipp, A. L. 2008. Field guide to Wisconsin sedges: An introduction to the genus Carex (Cyperaceae). University of Wisconsin Press, Madison. Houseal, G. 2010. Plasticulture or seed production of wetland (Carex) species. Native Plants Journal. 11:58-64. Houseal G., and D. Smith. 2010. Upland sedge (Carex spp.) propagation for seed increase. In: B. Borsari, director and coordinator. Proceedings of the twenty-first North American Prairie Conference, The prairie meets the river. Winona (MN): Winona State University, Winona, MN. Kettenring, K. M., G. Gardner, and S.M. Galatowitsch. 2006. Effect of light on seed germination of eight wetland Carex species. Annals of Botany 98:869-874. Kettenring, K. M., and S. M. Galatowitsch. 2007. Tools for Carex revegetation in freshwater wetlands: Understanding dormancy loss and germination temperature requirements. Plant Ecology 193:157-169. Lamont, W. J. Jr. 2004. Production of vegetables, strawberries, and cut flowers using plasticulture. Center for Plasticulture, Penn State University, University Park, PA. At http://plasticulture.psu.edu/node/118. Norris, W. R., and S. C. Zager. 2008. A guide to the identification of sedges in the genus Carex (Iowa species), 3rd edition. Self-published by authors (norrisw@wnmu. edu; [email protected]). Prairie Moon Nursery. 2010. Catalog and cultural guide, native seeds and plants for prairie, wetland, savanna, and woodland. 32115 Prairie Lane, Winona, MN 55987. At www.prairiemoon.com. Schütz, W., and G. Rave. 1999. The effect of cold stratification and light on the seed germination of temperate sedges (Carex) from various habitats and implications for regenerative strategies. Plant Ecology 144:215-230. 2 2 n d N o r t h A m e r i c a n p r a i r i e c o n f e r e n c e | S EED A ND S OI L ECO L O G Y

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