Location: Rangeland and Pasture Research2009 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
Considerable progress has been made for the ongoing breeding and evaluation projects for eastern gamagrass and Texas bluegrass. Controlled crosses have been made in the greenhouses; seeds from hybrid lines have been germinated and transplanted into field plots; and breeding lines have been evaluated under field conditions. Controlled crosses of 15 sand bluestem germplasm lines are being made in the greenhouse to develop a complete diallel. Cycle 1 selections of little bluestem have been made to produce three to five populations for improved forage and seed production. A study continues to evaluate six management strategies to minimize the effects of the Southern Cornstalk Borer on eastern gamagrass seed production. The treatments consist of single or dual application of two insecticides used to control stalk borers in corn fields.
1. The southern corn stalk borer in eastern gamagrass: Scientists at the Southern Plains Range Research Station, Woodward, Oklahoma, investigated the life cycle of the Southern corn stalk borer (SCSB) in eastern gamagrass. Adults SCSB were observed the last week of May in field plots. Mating, oviposition, and first hatch took place late May into early June. Larvae bored into the base of the culm where they fed, causing extensive damage to the culm, which eventually died. Pupation occurred within the feeding cavity. Metamorphosis became complete when adult SCSB emerged from the feeding cavity. Understanding the life cycle of the SCSB in eastern gamagrass will aid in the development of control measures for this insect.
2. Screening Texas bluegrass for host suitability to greenbug: Greenbug biotype E is the predominant biotype in the southern Great Plains, infesting winter wheat and sorghum; biotype F is known to damage certain bluegrass species. It is thought that greenbug biotypes may evolve on native grasses. Scientists at the Southern Plains Range Research Station determined that certain native cool-season Texas bluegrass genotypes collected from northwest Oklahoma are capable of supporting both greenbug biotype E and F growth and reproduction. These results indicate that Texas bluegrass can be an alternate host for greenbug biotype evolution. Thus it's important that breeding programs screen for greenbug resistance when developing improved forage and turf featuring Texas bluegrass.