Proc. 57th Southern Pasture and Forage Crop Improvement Conference, Athens, GA April 23-25, 2002

Collecting, Breeding and Evaluating Native Warm-Season Grasses in Kentucky

Tim Phillips, Associate Professor, Dept. of Agronomy, University of Kentucky

Interest in native warm-season grasses (NWSGs) for use as summer forage for livestock, wildlife habitat, prairie restoration, and ornamental landscape plants has increased over the past decade. Native plant proponents have recommend the use of locally adapted populations over readily-available commercial cultivars which may have originated several hundred miles away from the site. Erosion of local genetic variation may result when alien germplasm is introduced. Pre-settlement Kentucky may have had up to 25% of its acreage in prairies and grasslands. Early references describe large expanses of native cane [Arundinaria gigantea (Walt.) Muhl.] on which herds of bison would have grazed. Western Kentucky would have contained large tracts of tall grass prairie species including switchgrass (Panicum virgatum L.), indiangrass [Sorghastrum nutans (L.) Nash], big bluestem (Andropogon gerardii Vitm.), little bluestem [Schizachyrium scoparium (Michx.) Nash], and eastern gamagrass [Tripsacum dactyloides (L.) L}. Additional minor species of grasses, along with the previously mentioned tall grass prairie species, can still be found in relict stands and glades across Kentucky. In this paper, I discuss my efforts to collect, breed, and evaluate native warm-season grasses in Kentucky.

Beginning in 1993, the forage grass breeding project at the University of Kentucky collected seed of NWSG encountered in our trips around the state. Collection sites ranged from highway rights-of-way to stream banks, farmers’ fields, and areas identified by county agricultural extension agents. Indiangrass has been the most frequently observed NWSG on our collecting trips. Big bluestem and eastern gamagrass collection sites have been restricted to the western half of Kentucky. Switchgrass has been collected from central Kentucky and western Kentucky, but some of these sites may have been areas planted by the Kentucky Transportation Cabinet during the late 1960s. Most of the switchgrass germplasm that we have collected is the upland type, similar to Cave-in-Rock. Another source of germplasm was a 15 year-old stand of a population called ‘KY-1625′. This population had been growing at the Spindletop Agronomy Research Farm in Lexington, KY.

Beginning in 1999, I started teaching a grass taxonomy class. I have gathered many dozens of species from areas around Kentucky for identification and teaching demonstrations. Many of these species have some potential as landscape ornamentals, including many of the NWSG / tall prairie grass species. Additional species that have been collected include bushy bluestem [Andropogon glomeratus (Walt.) BSP], Elliot’s broomsedge (Andropogon gyrans Ashe), several species of plumegrass (Erianthus = Saccharum spp.), and several species of Elymus. The primary criteria for usefulness as an ornamental are lodging resistance, persistence, and showiness.

In 1995, selections were made from come highly variable collected populations for uniformity in heading, height and phenotype (color, leaf width). Other populations were bulked and planted as an increase of the collected seed or ramets. Switchgrass was especially variable for color (yellow-green vs. blue-green), but all species had variability in heading date. Six experimental synthetics of switchgrass were created in 1995, along with two indiangrass synthetics, two eastern gamagrass synthetics, and one big bluestem. In 1996 additional indiangrass and eastern gamagrass increase blocks were established from existing stands.

Plots were established in July, 2000 from transplants. Seed or ramets were obtained, and seedlings were grown in the greenhouse prior to transplanting to the field. This was done to remove the confounding factor of variable stand establishment for these species. These plots have been harvested for seed yield for several years. Evaluation of some of these experimental synthetics began in July, 2000, when the Forage Variety Testing Program at the University of Kentucky planted four yield trials of NWSGs. These studies are supported by the Wildlife Department of Kentucky, and are intended to provide information about suitability of these populations and cultivars for wildlife habitat. Kentucky-collected or originating populations are being tested in comparison with commercial cultivars. In 2001, two harvests were made for biomass yield for big bluestem, eastern gamagrass, and switchgrass. Indiangrass matures latest among these species, and only one harvest was taken in 2001. Other traits measured were time of heading and height at heading. Results from the 2001 season demonstrate the variability of these species and entries within each species (Table 1). The highest yielding entry was Alamo, a lowland-type switchgrass. Several Kentucky experimentals showed symptoms of panicum mosaic virus infection, which reduces growth. Big bluestem entries all yielded similar amounts (4.37-4.83 tons/acre). Indiangrass entries attained the greatest heights at time of heading, and was by far the latest species to reach maturity among these species..

Table 1. Dry matter yield (tons/acre), maturity date, and height at maturity of native warm season perennial grass species planted July 18, 2000 at Lexington KY.

		Yield			Maturity	Height
Species	Variety	6Jul01	8Aug01	Total	JD at 50%	Inches at 50%
Big bluestem	Pawnee	3.43	1.40	4.83	194	46
	Kaw	3.41	1.37	4.78	191	53
	Roundtree	3.27	1.40	4.67	194	48
	KYAG9601	3.05	1.32	4.37	201	42
Eastern gamagrass	KYTD9601	3.45	4.46	7.91	179	45
	PMK-24	2.56	3.82	6.38	179	41
	RMF	1.52	3.47	4.98	182	33
Indiangrass	NE54		7.12	7.12	220	59
	Cheyenne		6.44	6.44	227	65
	Rumsey		6.25	6.25	230	64
	Osage		6.24	6.24	223	59
Switchgrass	Alamo	5.60	3.08	8.68	186	51
	Cave-in-Rock	4.89	2.37	7.26	179	46
	KYPV9504	3.98	1.55	5.53	183	44
	KYPV9505	3.83	1.68	5.52	183	35
	KYPV9506	3.49	1.58	5.08	182	35
	Trailblazer	3.84	0.56	4.41	182	41

(Data courtesy of Robert Spitaleri and Jimmy Henning, UK Forage Variety Testing Program.)

The study will be harvested for a second season in 2002. Another study is planned in which entries are seeded, and additional entries from our collections and breeding programs will be included. NWSGs can be used to fill the summer slump for cool season forage grasses, for wildlife habitat, and landscape diversity.