Location: Rangeland and Pasture Research2012 Annual Report
1a. Objectives (from AD-416):
The objectives of the proposed research are: 1) to breed eastern gamagrass [Tripsacum dactyloides (L.) L.] cultivars improved for biomass yield and other performance traits, 2) to breed and evaluate Texas bluegrass (Poa arachnifera Torr.) cultivars and interspecific hybrid cultivars (P. arachnifera x Poa species) improved for selected performance traits, 3) to develop a diallel population of sand bluestem (Andropogon hallii Hack.) from 15 diverse accessions and to evaluate sand bluestem germplasm lines with improved establishment capabilities, 4) to breed little bluestem [Schizachyrium scoparium (Michx.) Nash] cultivars with improved forage and seed production, and 5) to determine the life history of the southern cornstalk borer (Diatraea crambidoides Grote) in eastern gamagrass. To meet objective 1 we will use conventional methods to breed eastern gamagrass with improved vigor, seed production and persistence in the Southern Plains region. In objective 2, conventional methods will be used to breed Texas bluegrass cultivars and interspecific hybrid cultivars for improved vigor, rust-resistance, and persistence. In addition low-input turf cultivars will be developed. In objective 3, an attempt will be made to create a diallel population of seeds from 15 sand bluestem lines collected from the Southern Plains. Also, an evaluation will be made of sand bluestem germplasm lines selected for improved seedling establishment. In objective 4, we will use phenotypic mass selection to improve little bluestem for forage and seed production traits. Three to five diverse populations will be created on the basis of visual ratings for plant color, growth, disease incidence, leafiness, plant height at anthesis, and on determination of percentage seed set. For objective 5, the life cycle of the southern cornstalk borer will be examined in eastern gamagrass. Understanding the life cycle of this insect is a key to developing management strategies to avoid peak damage of this insect.
1b. Approach (from AD-416):
The overall approach is to identify germplasm with desirable traits, to expand the limits of germplasm variation by wide hybridization utilizing interspecific and intergeneric introgression and genetic manipulation, to evaluate and select superior genotypes, and then release superior germplasm and improved cultivars. A broad-base germplasm collection of eastern gamagrass is maintained at the Southern Plains Range Research Station at Woodward, OK. Facilities include 10,000 sq. feet of glass house space, a cytological-molecular laboratory equipped with light and fluorescent microscopes, karyotyping work station, RAPD-PCR accessories, sterile laminar flow hood, four growth chambers, -80 C freezer, and ample acreage for field trials and nurseries. This research will involve basic agronomic, physiology, genetics, cytogenetics and molecular biology studies.
3. Progress Report:
This is the final report of Project 6216-11210-007-00D that will end in November 2012. ISSR markers were used to develop DNA fingerprints of Texas bluegrass and interspecific hybrids. Nine of 17 ISSR primers consistently produced robust fingerprints, allowing for early detection of hybrids in the breeding program. The population dynamics of biotype E and biotype F greenbug were evaluated on bluegrass species and interspecific hybrids. Biotype E greenbug had a higher population growth rate as compared with biotype F on Texas bluegrass. Both Canada and Kentucky bluegrass supported high populations of biotype F and interspecific hybrids varied in their host suitability to biotypes. The life cycle of the southern cornstalk borer (SCSB) in eastern gamagrass was determined and can be described as overwintering, first generation, and second generation populations. This was completed in approximately 911 cumulated growing degree days. The agronomic performance of eastern gamagrass cultivars (Bumpers, Highlander, Pete, and Verl) and three germplasm lines were determined. Forage yield and quality were similar among cultivars but differed for seed production. Compared to cultivars, germplasm lines were lower in forage yield and quality but equal to or higher in seed production. Two cycles of recurrent selection were used to develop sand bluestem populations AB-medium Syn-1 and Syn-2 from population AB-medium Syn-0 and populations CD-tall Syn-1 and Syn-2 from population CD-tall Syn-0. Selection pressure consisted of germinating seeds of each Syn-0 population in a -0.8 MPa mannitol solution for 7 d. In the laboratory, germination of Syn-1 seeds was 6.7% higher than Syn-0 seeds and Syn-2 seeds were 10.2% higher than Syn-1 seeds. The variation in traits that contribute to canopy morphology within and among little bluestem parental lines and an F1 plant population were described. Plants were classified as not upright (NU), upright compact (UC), or upright open (UO) on the basis of their shape. Parental lines expressed considerable variation for frequencies of discrete and continuous morphological traits. The F1 plant population was characterized by 12.2% NU plants, 22.4% UC plants, and 65.4% UO plants. Little bluestem is an ideal species for breeding new cultivars for pasture and rangeland renovation, roadside revegetation, wildlife habitat, and recreation areas. The biomass yield from an urban landscape was estimated from 13.5-19.0 Mg per planted hectare for high rainfall years and 8.0-12.3 Mg for normal rainfall years. Biomass from urban landscapes is an untapped resource, and further research is needed to fully explore its potential.
1. Examining the life cycle of the Southern corn stalk borer (SCSB) in eastern gamagrass. The SCSB is a serious pest of eastern gamagrass, and understanding the life cycle of this insect will aid in developing control methods. ARS scientists at Woodward, Oklahoma, investigated the life cycle of the SCSB in eastern gamagrass. Adult SCSB were observed the last week of May in field plots at Woodward. Mating, oviposition, and first hatch took place late May into early June. Larvae bore into the base of the shoot where they feed. This causes extensive damage to the shoot, which eventually dies. Pupation occurs within the feeding cavity and metamorphosis is complete when adult SCSB emerge from the feeding cavity. The life cycle of the SCSB in eastern gamagrass was completed in approximately 911 cumulated growing degree days. This new knowledge will help researchers devise methods for controlling the SCSB, and thus help to assure the future of eastern gamagrass in the USA.
2. Selection of sand bluestem lines for improved seed germination. Under field conditions, water is often inadequate for satisfactory seedling establishment (germination and emergence) of sand bluestem, a native grass important to the southern Great Plains, in low moisture conditions. An ARS scientist at Woodward, Oklahoma, used two cycles of recurrent selection to develop a sand bluestem line with greater seed germination. Selection consisted of germinating sand bluestem seeds in a low moisture environment and selecting the seed that germinated. Approximately 7% of the seed germinated in each selection cycle; however, the average seed germination of the selected sand bluestem line was 16.9% units higher than that of the unselected line. The selected sand bluestem line was tested at three locations in the central and southern Great Plains over a four-year period and is being prepared for release as an improved cultivar.
3. Selection of little bluestem for canopy shape. Little bluestem is a native grass that has been shown to have high levels of genetic variation for traits such as biomass yield, disease resistance, plant height, leafiness, maturity, and seed yield. If high levels of genetic variation exist for these traits, it is likely that it would exist for other traits as well. An ARS scientist at Woodward, Oklahoma, described the variation in traits that contribute to canopy shape within and among little bluestem parental lines and hybrid plant populations. Seven plant populations characterized by three unique canopy shapes were developed, which make them ideal for breeding new cultivars for pasture and rangeland renovation, roadside revegetation, and wildlife habitat.
4. Capitalizing on urban biomass. Utilizing biomass from urban landscapes could significantly contribute to the nation's renewable energy needs. An experiment was conducted by an ARS scientist to evaluate the biomass production from a bermudagrass lawn in Woodward, Oklahoma, and to estimate the potential biomass yield for the City of Woodward. In years of high rainfall, it was possible to harvest from 13.5 to 19.0 Megagrams (Mg) of dry biomass per planted hectare from an urban landscape and 8.0 to 2.3 Mg of dry biomass per planted hectare were possible in years with normal rainfall. It was estimated that the City of Woodward could generate about 3,750 Mg of biomass dry matter in a normal rainfall year and about 6,100 Mg in a high rainfall year if every homeowner collected their lawn thatch, lawn clippings, tree leaves, and tree prunings for bioenergy production. On the basis of a 10 Mg/ha DM yield, there is an estimated 164 million Mg of biomass DM material collected and/or recycled in the USA from urban areas annually. Biomass from urban landscapes is an untapped resource, and further research is needed to fully understand the potential of this resource.Springer, T.L., Puterka, G.J., Maas, D.L., Thacker, E.T. 2011. The southern cornstalk borer (Diatraea crambidoides (Grote), Lepidoptera: Crambidae)a new pest of eastern gamagrass (Tripsacum dactyloides (L.)L., Poaceae). Journal of the Kansas Entomological Society. 84(3):209-216.