Narrative
The Agricultural Research Service, Southern Plains Range Research Station, in Woodward, Oklahoma, and the Natural Resources Conservation Service, James E. “Bud” Smith Plant Materials Center, in Knox City, Texas announce the release of ‘Sims’ little bluestem [Schizachyrium scoparium (Michx.) Nash]. Sims was selected for its columnar growth morphology, rapid laboratory seed germination, and excellent field establishment. Sims is recommended for wildlife habitat, grazing utilization, roadside stabilization, renewable energy, and horticultural landscapes in the southern Great Plains of the United States.Selection of Sims little bluestem: Sims was selected out of little bluestem germplasm UC-2 (PI 676265) through two cycles of phenotypic recurrent selection for greater 7-d laboratory seed germination in water of ‒0.8 MPa potential. UC-2 germplasm was selected at the USDA-ARS Southern Plains Range Research Station, Woodward, Oklahoma. It is tolerant of soil pH=8, leaf rust caused by Puccinia andropogonis, and culm lodging. The plant canopy height of UC-2 germplasm averages 1.2 m and the canopy width averages 0.5 m. The average flowering date at Woodward, Oklahoma was 20 September. The adaxial leaf color varies from 2.5GY /4/2 to 7.5GY /6/8 on the Munsell Color charts for plant tissues, and the abaxial leaf color varies from 5GY /4/2 to 7.5GY /7/8. Approximately 83% of culm leaf blades are greater than 10 cm long, 79% of leaf blades are less than 5 mm wide, 63% of leaves are attached at an angle of less than 90 degrees, and approximately 60% of plants have few if any leaves at the base of the culm. Selection Cycle 1: Selection pressure consisted of germinating 3,500 pure seeds of UC-2 germplasm in water of −0.8 Megapascal (MPa) potential for seven days. All seeds that germinated within seven days were removed from the germination container, washed with water, planted into greenhouse trays, and held for field transplanting. The selected plants were hand transplanted into a field plot where they produced seeds for the next generation. The harvested seeds were designated as little bluestem population ‘UC-2 C1’. Selection Cycle 2: Cycle 2 selection was the same as cycle 1 except that pure seeds of population UC-2 C1 were germinated and selected as outlined above to produce the next generation of seeds designated as little bluestem population ‘UC-2 C2’. Sims little bluestem was tested under the experimental designations of either ‘UC-2 Syn-2’ or ‘UC-2 C2’. Laboratory Seed Germination: Laboratory seed germination experiments were conducted to compare Sims little bluestem with three adapted cultivars ‘Ahring’, ‘Aldous’, and ‘Cimarron’ using standard germination protocols for little bluestem. The seed germination of Sims little bluestem averaged 68% at seven days, which was significantly greater than both Cimarron and Aldous, averaging 29 percentage points higher than Cimarron and 15 percentage points higher than Aldous at seven days. The germination of Sims, however, was not significantly different from that of Ahring. Ahring little bluestem, like Sims, was selected for rapid laboratory seed germination in water of −0.8 MPa potential. Sims and Ahring little bluestem, however, have different canopy morphologies. Sims little bluestem has an upright and compact canopy morphology (a columnar shape with erect culms) compared with an upright and open canopy morphology (a caespitose shape with ascending culms) of Ahring. Spikelet mass: The average mass of 50-spikelets of Sims little bluestem was similar to Aldous, but less than both Ahring and Cimarron. The mass of 50 spikelets of Sims and Aldous averaged 100 mg compared with 106 mg for Cimarron and 133 mg for Ahring. Field Emergence: The field establishment and biomass production experiments were conducted in small plot performance trials near Enid and Woodward, Oklahoma, and Knox City, Texas for three years (2018−2020). Plots were drilled at the pure live seed (PLS) rate of 108 seeds m–2. Averaged over nine field environments, the establishment plant population density of Sims little bluestem at 60 days after planting averaged 9 plants m–2. The plant density of Sims at 60 days after planting was similar to both Ahring and Cimarron but was greater than Aldous. Sixty days after planting the percentage field emergence of Sims averaged 32%. Like plant population density, the percentage field emergence of Sims little bluestem was similar to the cultivars Ahring and Cimarron, but greater than Aldous. Biomass Yield and Forage Quality: Biomass was harvested from plots the year following establishment. Plots sown in 2018 were harvested in 2019 and plots sown in 2019 were harvested in 2020. Biomass was harvested at a stubble height of 10 cm. Biomass yield was similar among all bluestem cultivars and averaged 6.4 Mg ha−2. The whole plant crude protein (CP) and in vitro organic matter digestibility (IVOMD), however, varied among the cultivars. The CP concentration of Sims averaged 70 g kg−1 on a dry weight basis, which was similar to Ahring and Cimarron, but 4 g kg−1 less than Aldous. The IVOMD concentration of Sims averaged 483 g kg−1 on a dry weight basis, which was similar to Ahring and Cimarron, but 22 g kg−1 less than Aldous. Lastly, the forage ash concentration of Sims averaged 60 g kg−1 on a dry weight basis and was not different from the other adapted cultivar. Sims Ranking among Little Bluestem Cultivars: The rank scores for the selected variables 7- day laboratory seed germination and plant field density, were 1.0 for the cultivar Ahring, 2.0 for Sims, 3.5 for Cimarron, and 4.0 for Aldous. Sims little bluestem, however, was identical to Ahring for 7-day laboratory seed germination and plant establishment density and consistently outperformed the adapted cultivars Aldous and Cimarron for these same traits. Canopy morphology is an important trait associated with wildlife habitat, grazing utilization, roadside stabilization, and renewable energy. The trait that distinguishes between Sims and Ahring is canopy morphology. Sims has an upright and compact (columnar with erect culms) canopy morphology compared to the upright and open (caespitose with ascending culms) canopy morphology of Ahring. General Information. Sims little bluestem is a stable, random mating population with improved laboratory seed germination and field emergence. It is a publicly released cultivar and not protected. Sims is adapted to USDA Plant Hardiness Zones 6 and 7 of the Great Plains Region. Breeder’s seed will be maintained for a period of five years following formal release by USDA- ARS. Small quantities of seed can be requested through the USDA-ARS Southern Plains Range Research Station, 2000 18th St., Woodward, Oklahoma 73801, (580) 256-7449 and are subject to availability of seed stocks.Seed of Sims little bluestem will also be deposited in the USDA-ARS National Plant Germplasm System where it will be available for research purposes, including the development and commercialization of new cultivars. Appropriate recognition is requested if this release contributes to the development of new cultivar(s), germplasm release(s), and /or scientific discovery(s). Sims little bluestem was named to honor the late Dr. Phillip L. Sims (1940−2014), Research Leader, Southern Plains Range Research Station, Woodward, Oklahoma. Dr. Sims was a gifted scientist passionate about rangelands. His knowledge of plant communities and livestock enterprises was known throughout the world. He was a friend, mentor, and supervisor.