Location: Crop Genetics and Breeding Research2011 Annual Report
1a. Objectives (from AD-416)
To develop and evaluate bermudagrass, napiergrass, pearl millet, and rhizoma peanut for forage production and for alternative uses in the southeastern U.S.; to enhance bioenergy production from warm-season grasses; and to apply molecular genetic technology to improve grass species adapted to the southeastern U.S.
1b. Approach (from AD-416)
Develop and select improved populations and germplasms of bermudagrass for forage, bioenergy, and turf; develop and select improved populations and germplasms of napiergrass for forage and bioenergy; develop and select improved populations, inbreds, and hybrids of pearl millet for forage, bioenergy, and wildlife; and select improved rhizoma peanut germplasms for forage. Evaluate genotype and production effects on ethanol production from pearl millet; assess genotypic differences in bermudagrasses, napiergrass, and pearl millet for conversion to fermentable product or through thermochemical techniques to syngas; and improve selection efficiency for superior forage and cellulosic feedstocks. Measure genetic diversity within bermudagrass, napiergrass, and pearl millet using molecular markers; and identify associations of molecular markers in bermudagrass and pearl millet with traits important for forage or alternative uses.
3. Progress Report
The goal is to develop improved grass and forage legume germplasm and varieties that can be more efficiently converted into livestock, bioenergy, turf, and bioproducts that can be produced in a variety of environments. Activities focused on the genetic improvement of pearl millet, napiergrass, bermudagrass, and rhizomatous peanut for forage, bioenergy, and alternative uses. Bermudagrass populations were assessed a second year for yield and will be used in recurrent selection. The bermudagrass core collection continued to be evaluated for nitrogen use efficiency and cold tolerance while selections were made within the core for advanced testing for shade tolerance. Napiergrass hybrids were evaluated for a fourth year for growth traits, persistence and cold tolerance from an unusually cold winter, and selections were evaluated a second year in a replicated yield trial. Napiergrass and bermudagrass continued to be assessed for conversion to ethanol via different pre-treatments for biochemical conversion. Differences in species, genotypes, and harvest times have been reported via manuscripts. Rhizoma perennial peanut lines were evaluated for a fourth year for differences in yield and establishment characteristics and results were published from the first three years of research. Two experimental pearl millet hybrids were identified with greater than 30% greater yield over the commercial standard and inbreds used in developing these hybrids were characterized. No-till practices were evaluated to improve production economics for pearl millet. Root-knot nematode resistance was evaluated in a mapping population. Bermudagrass expressed sequence tagged simple sequence repeat (EST-SSR) markers were developed and used to create bermudagrass genetic maps (Cynodon dactylon and Cynodon transvaalensis) and work indicated that tetraploid bermudagrass is an allotetraploid. The EST-SSR markers are currently being used to differentiate many of the commercially used bermudagrass cultivars and for cultivar and pedigree identification among bermudagrass turf types. First of their kind simple sequence repeat (SSR) markers for measuring diversity in centipedegrass were also developed.
1. Development of genetic tools for turf grass breeding and identification. Molecular markers could greatly reduce the amount of time, expense and effort needed for traditional breeding of turf and can be used to identify turf cultivars for proprietary rights and plant stock certification. For the last 40 years, a major problem with golf courses in the southeastern United States has been natural mutants that arise from the bermudagrass triploid ‘Tifgreen’ or one of its somatic mutants that are frequently released as cultivars. These natural mutants, or off-types, cause inconsistencies in appearance and playability and respond differently to nutrients, herbicides, and growth regulators resulting in severe problems and millions of dollars in losses to golf courses and sod farms. ARS researchers at Tifton, GA generated a new set of simple sequence repeat markers (SSR) markers of which five primers amplified fragments that distinguished between ‘TifEagle’, ‘MiniVerde’, and ‘Tifdwarf’. Furthermore, these polymorphisms were present in only certain tissue types (in shoot tissue but not root tissue) indicating that many of these cultivars are somatic chimeras. These markers are currently being used by ARS to identify bermudagrass cultivars for golf course superintendants, sod farms, businesses, and university researchers.
2. The effects of varying levels of nitrogen (N), phosphorus (P) and potassium (K) on yield, nutrient uptake and soil attributes of Tifton 85 and Coastal bermudagrasses. Most fertilization recommendations for forage bermudagrass (Cynodon dactylon L.) are based on extensive research with ‘Coastal’ bermudagrass which has been grown throughout the Southeastern United States since its release in 1943. Tifton 85, having higher yields and better forage quality, was released in 1993. The biochemical make-up of Tifton 85 has been documented to be different than Coastal, resulting in higher ruminal digestibility. A 4-year study was concluded in 2007 at two sites for Tifton 85 to determine the effects of six nitrogen rates and three phosphorus/potassium levels on mineral uptake, dry matter yields, and soil mineral composition. Dry matter yields responded to nitrogen levels significantly in all years up to 400 lbs/acre, predominantly in the first and last of five clippings. Yield differences among P-K treatments were observed in the third and fourth year of the study. Preliminary economic analysis indicates that only N rates at or below 400 lbs/acre result in a net return due to high input costs. Results of this study will help hay producers and ranchers better manage their Tifton 85 pastures.Cutts, G., Grey, T., Vencill, W., Webster, T.M., Lee, R., Tubbs, R., Anderson, W.F. 2011. Herbicide Effect on Napiergrass (Pennisetum purpureum Schum.) Control. Weed Science. 59(2):255-262.