NE1010: Breeding and Genetics of Forage Crops to Improve Productivity, Quality, and Industrial Uses
(Multistate Research Project)
NE1010: Breeding and Genetics of Forage Crops to Improve Productivity, Quality, and Industrial Uses
Duration: 10/01/2002 to 09/30/2017
Statement of Issues and Justification
The economics of farming continues to be one of the major agricultural problems in the U.S. One important component of the solution is to increase profitability by crop improvement through plant breeding. Improved forage cultivars provide economic opportunities for livestock and crop farming operations and promote a more stable, sustainable agriculture. Farmers benefit by greater animal product per unit of land or forage produced, and the consumer benefits by maintenance of low cost food. Improved seed production capacity also ensures a satisfactory product for seed producers and a low seed price to the forage grower. All Americans benefit as genetic improvement is the least costly and most stable way to maintain international agricultural competitiveness, decrease the amount of land lost to agricultural production, and protect the environment by decreasing the use of pesticides, herbicides, and fertilizers.
Multistate cooperative research by NE-144 impacts directly upon all five national goals of the "Agricultural Research, Extension, and Education Reform Act of 1998." These goals are: (1) an agricultural system that is highly competitive in the global economy, (2) a safe and secure food and fiber system, (3) a healthy, well-nourished population, (4) an agricultural system which protects natural resources and the environment, and (5) enhanced economic opportunity and quality of life for Americans. What follows is a description of the problems, the general role of forage species in helping to solve these problems, and the specific role of forage breeders in researching these problem areas.
Forage crops constitute the foundation of livestock and dairy enterprises in the U.S. and Canada while also serving vital environmental functions. In order for livestock farms to be profitable, for environmental goals of reduced pollution and sustainability to be met, and for consumers to have meat and milk products available at low prices, forage cultivars with improved persistence, quality, and productivity need to be developed. As budget reductions have resulted in fewer forage breeding positions, the need for cooperative research to develop germplasm and cultivars with new traits is essential. The paucity of forage breeding belies the value of forage crops: measured solely as the value of hay, forages rank 4th behind corn, soybean, and wheat in cash receipts among all U.S. field crops. Yet, the combined number of scientist-years (SY) devoted to forage breeding at all state agriculture experiment stations is fewer than one for each species, with the exception of alfalfa, which had 15 SY's in 1994. For comparison, corn, soybean, and wheat had 32, 45, and 65 SY's respectively. Furthermore, half of all US plant breeding efforts, public and private, are devoted to corn, soybean, cotton, and wheat. Among all forage crops, only a few (alfalfa, perennial ryegrass) receive any investment from private breeding companies. Those companies are disappointed that public institutions do not devote enough research on new traits and on forage species that companies do not breed.
Furthermore, all perennial forage species must be broadly adapted to market the volume of seed required to justify its production and marketing. Evaluation of genotypes, germplasm, and new cultivars must be done at multiple locations. A system currently is in place to accomplish this extensive evaluation among NE-144 cooperators. In addition, m,olecular marker systems have shown their potential usefulness for forage improvement, but prohibitive costs prevent all breeders from having laboratory facilities. The current NE-144 committee fosters the interactions necessary to accomplish more breeding with diminishing resources without unnecessary duplication of breeding efforts. Thus, enhancing our knowledge of forage crop breeding and genetics and developing improved germplasm and cultivars can only be done through collaboration among public scientists.
Plant breeders can improve pest resistance, persistence, and quality of forage crops without reducing forage yield potential (Anderson et al., 1988; Eichorn et al., 1986). These improvements can be made without passing increased seed costs to the farmer and without the need for increased management or input costs (Vogel et al., 1981). Thus, the farmer benefits by producing more animal product per unit of land or forage, and the consumer benefits through low cost food. Improved seed production capacity, or even maintenance at accepted levels, also ensures a satisfactory profit for seed producers and an acceptable seed price to forage growers.
The cooperative research with new traits, breeding methodologies, and molecular markers ultimately will result in new germplasms and cultivars that will enhance more economical production of forages and production of livestock products. Therefore, we will help foster a more diversified agricultural system that relies less on commodity grain production and improves agricultural sustainability.
Agriculture is the largest nonpoint source of water pollution in the U.S., accounting for 50% of all water pollution (Chesters and Schierow, 1985; Myers et al., 1985). Agricultural runoff carries nutrients, pesticides, and sediment into surface waters. Approximately 20% of U.S. cropland is subject to serious damage by erosion (Clark et al., 1985; USDA, 1987a and 1987b). Perennial forage crops are the most effective source of cropland vegetation in reducing water runoff and topsoil removal (Reganold et al., 1987; Wadleigh et al., 1974; Wischmeier and Smith, 1978). Their high level of ground cover and extensive root systems reduce soil erosion, increase water percolation, and reduce nutrient loading of both surface and ground water. Their perenniality also reduces the frequency of heavy tillage operations required in crop rotations. Reducing frequency of tillage reduces runoff and pesticide loading of surface waters (Glenn and Angle, 1987). In addition, tilled fields without cover crops are more susceptible to erosion and leaching of applied chemicals than are fields with a high level of ground cover (Hoyt and Hargrove, 1986; Reganold et al., 1987). A reduction in the use of forage crops has made control of soil erosion difficult in some regions (NRC, 1989).
Legume-based crop rotations can sustain high levels of grain production without the use of nitrogen fertilizer (Power, 1987). Legume cultivars with greater persistence, N2 fixing ability, disease and insect resistance, and greater resistance to environmental stresses will be extremely useful in the development and implementation of environmentally sound crop production systems.
Changes in crop production strategies toward reduced nitrogen fertilization and greater use of forage mixtures, will require changes in breeding strategies for continued development of improved cultivars and germplasm. Development of superior perennial grass cultivars for use in low applied nitrogen crop production systems will require breeding efforts under similar conditions. In perennial grasses, cultivars with the highest yield and quality under high nitrogen rates are not always the cultivars with the best performance under low nitrogen rates (Vose, 1963). Different nitrogen levels can also cause different genotypes to be selected from breeding nurseries. Grasses adapted to use in grass-legume mixtures may be more productive and stable than in monocultures (Chamblee and Collins, 1988) and have fewer weed problems (Drolsom and Smith, 1976). Breeding and testing under monoculture conditions does not allow selection of genotypes or cultivars with maximum performance in mixtures (Casler and Drolsom, 1984).
Cool-season forage species are extremely versatile with broad collective adaptation to virtually any cultivated lands in the northern U.S. and Canada. Therefore, they are often relegated to poorer soils and sites less conducive to row-crop production, such as waterlogged soils, hard pans, droughty sites, etc. Species such as alfalfa are highly productive on good soils but have severe production problems on heavy, wet, or acid soils. Other forage species are well adapted to each of these conditions and provide excellent alternatives under those circumstances. In addition, selection procedures can be used to genetically modify species for adaptation to stressful soil conditions (Charles, 1972; Snaydon, 1978). Breeding cool-season forage crops for resistance or tolerance to various environmental and biological stresses is an important component of research designed to maximize the efficiency of animal production on various types of marginal lands. Unfortunately, little support for these breeding programs exists outside of publicly funded institutions.
The use of pastures is widely practiced in the northern U.S. and Canada. It is an alternative means of producing high quality feed without the need for input costs associated with harvesting, processing, and storing cured feeds. Technological advances of the mid-20th century and the results of dairy production experiments (Larsen and Johannes, 1965) led to the widespread practice of hay and silage production from forage crops. Forage breeders, in their attempts to provide the best products for accepted management systems, followed this trend. Forage crop cultivars well adapted to hay and silage management systems tend to be more upright in growth habit, less densely-tillering, and earlier in maturity than those adapted to pasture systems (Stapledon, 1928). Consequently, cool-season forage crop cultivars are relatively unadapted to the frequent, intensive, rotational grazing systems (Voisin, 1988) now being adopted by many farmers.
Collaborative regional research is an essential component of an effective North American forage breeding research and cultivar development system. Forage breeders are trained at widely divergent institutions, which have differing specialties, resources, and philosophies. Most breeders have a secondary area of specialization, typically plant pathology, entomology, plant physiology, biometry, quantitative genetics, molecular genetics, or cytogenetics. Collaboration on specific shared objectives is an efficient means of combining resources and expertise into important researchable objectives.
Forage breeding programs are unique in that nearly all forage breeding/genetics project leaders conduct research on multiple species. Although individual effort is small for some forage species, the cumulative impact from cooperative efforts among forage breeders is significant. Due to diversity among forage production environments and livestock production systems, farmers in any state or province collectively use a large number of species to meet their forage needs. No single breeder can conduct a research/cultivar development program on all species of economic importance. Furthermore, there are no public forage breeding programs in many important forage producing regions of the Northeast and Northcentral U.S., and few private companies actively breed perennial forages. As a consequence of these factors, relatively little effort is placed on some species for which important researchable goals remain unmet.
The members of the NE-144 Multistate Research Committee represent nearly all public efforts aimed at cool-season forage breeding in the humid, temperate portions of the U.S. and eastern Canada. The exceptions are a few alfalfa breeders and geneticists. Thus, research efforts described in this document do not represent duplication of any efforts underway in other institutions of the U.S. or Canada. A recent search of the CRIS system has further verified the validity of this conclusion.
Because of the long-term nature of research on perennial forage species, many of the collaborative efforts begun during the last NE-144 five-year period will continue into the next. In addition, completion of some efforts has led to new research projects that justify continued collaborative research in the proposed 15-year period. Furthermore, the high degree of collaboration among the NE-144 scientists will no doubt foster the initiation of additional collaborative efforts not yet envisioned.
Funding for these collaborative efforts will be only partially covered through the NE-144 project. Scientists currently supplement these cooperative research efforts with funding from other sources, such as from seed industry, royalties from seed of cultivars, and various sources of public funding (state and federal) for molecular and other types of research. USDA and Ag Canada participants fund their efforts from federal sources as well as from competitive grants. In addition, we anticipate that NE-144 funding will serve as seed or matching funds leading to more opportunities for research funding from other sources, as it has in the past.
Related, Current and Previous Work
Formal forage breeding efforts began just over 100 years ago (Hays, 1892; Smith, 1948; Beddows, 1953). Early cultivars were developed by intentional (Hays, 1892; Jenkin, 1943) or unintentional (Levy, 1932; Evans, 1937) selection for morphological or sexual reproductive traits. Over the years, breeding became more sophisticated as more complex traits such as quality and resistances to biotic and abiotic stresses needed to be incorporated into cultivars.
Alfalfa is considered by many ranchers to be a highly desirable component of semiarid pastures and rangelands (Lorenz, 1982; Ries, 1982). Interseeding alfalfa into rangeland and depleted pastures has been one approach to improve forage production and quality and animal performance (Lorenz, 1982). Berdahl et al. (1989) demonstrated that alfalfa populations with a high proportion of M. sativa subsp. falcata parentage had much higher survival, DM yield, and vegetative spread than M. sativa subsp. varia seven years after interseeding into rangeland near Mandan, ND. They also showed that populations of alfalfa that had persisted for over 50 years in association with rangeland grasses in western ND and SD survived grazing by sheep better than cultivars developed primarily for grazing in semiarid regions of the northern U.S. and southern Canada (Berdahl et al., 1986). Rumbaugh (1982) observed natural reseeding of alfalfa in 25-year-old pastures in southern UT. The parentage of that population traces back to plant introductions of falcata brought to western SD by N.E. Hansen during the early 20th century (Rumbaugh, 1979).
Lorenz (1982) suggested that introducing alfalfa to arid and semiarid rangelands was an efficient means of increasing animal output with a minimum input of fossil fuel energy. He also pointed out that to do that successfully would require the development of new cultivars that would be adapted to long-term productivity and persistence in an introduced legume-native grassland complex. Ries (1982) pointed out that for alfalfa to maintain itself in pastures or rangelands, it would have to have the capacity for recruitment since periodical reseeding would not be practical.
Evaluation of breeding material at multiple locations throughout a geographic region is the best means to develop cultivars with wide adaptation. Evaluation over a wide range of sites within or between regions is also useful in identifying the most appropriate sites for future tests (Barker et al., 1981). Additionally, some environments may be more conducive to selection progress than others (Snaydon; 1978; Casler and Walgenbach, 1990). However, many forage cultivars currently bred in Europe and North America are products of selection and breeding conducted at a narrow range of locations. The ultimate release and recommendation of a cultivar are often based on the results of a regional testing program, but are also frequently based on educated guesses and extrapolation on the part of the breeder. 'Saratoga' smooth bromegrass, perhaps the most broadly-adapted cultivar of this species based on high yield in many diverse environments (Casler and Ehlke, 1986) is a product of regional testing prior to synthesis and testing of the cultivar per se. Without region-wide interaction among breeders, the coordination necessary to develop broadly adapted cultivars cannot occur.
Germplasm collection and incorporation into breeding programs remains an important objective of most forage breeding programs (Breese and Tyler, 1986; Rumbaugh et al., 1988a; Casler, 1991). Because forage breeding is a relatively young discipline, forage crops are generally not as domesticated as most cereal crops (Harlan, 1975). Thus, collections of naturalized populations in many species have similar phenotypic characteristics as cultivated germplasm (Breese and Tyler, 1986; Rumbaugh et al., 1988b; Casler, 1991). Because introduced germplasm is adapted to very specific environments, in the case of natural collections (Snaydon, 1978; Rumbaugh et al., 1988b), or diverse production environments and management systems, in the case of cultivated germplasm from other countries, identification of superior germplasm for use in breeding programs requires evaluation in a wide range of target environments. Germplasm evaluations in a wide range of environments can be extremely useful in identifying the breadth of adaptation of individual accessions as well as environmental factors responsible for differences in performance or adaptation (Snaydon, 1978).
Genetic improvement of forage yield is extremely difficult and slow, due to low heritability and high genotype x environment interaction (GEI) (Barker and Kalton, 1989). Thus, many breeders have developed new selection criteria for indirect forage yield improvement, e.g., leaf area expansion rate (LAER) in tall fescue (Sleper and Nelson, 1989), specific leaf weight in reed canarygrass (Carlson, 1990), and leaf blade length in perennial ryegrass (Rhodes, 1969).
In addition to forage uses, perennial herbaceous crops can be grown for other reasons, such as biomass for energy. Conversion of plant biomass to fuel, either through fermentation to ethanol (Lynd et al., 1991) or via direct burning to generate electricity (McLaughlin, 1993), has a number of desirable attributes, including a reduced dependance on foreign fossil fuels and stabilizing greenhouse gasses in the atmosphere through carbon and nitrogen cycling. Other uses of these crops include paper pulp, hardboard for building construction, and pellets for use in home heating (Thons and Prufer, 1991; A. Teel, pers. comm.). Unfortunately, little effort has been directed toward the genetic characterization and improvement of most grasses for these uses.
The most promising cool-season grass for biofuel production is reed canarygrass. Because the most important restriction on cropland use in the Midwest and Northeast, after erosion, is wet soils (USDA, 1987a), reed canarygrass appears to be an ideal species. Reed canarygrass grows extremely well in wet soils, even withstanding inundation for long periods (Carlson et al., 1996). Its wet soil tolerance often overshadows its excellent drought tolerance, which makes it relatively more productive in the summer relative to other cool-season species (Carlson et al., 1996). Biomass productivity of reed canarygrass exceeded that of switchgrass in northern OH (Wright, 1988) and occasionally in southern IA (Anderson et al., 1991). Numerous other studies also have indicated that reed canarygrass produces excellent yields of total biomass (e.g. Cherney et al., 1986; Marten et al., 1980).
Until recently, all breeding research on reed canarygrass have focused on forage traits--palatability, seed retention, disease resistance, persistence, leafiness, etc. (Carlson et al., 1996). Maximum biomass per se is being evaluated on germplasm from the National Plant Germplasm System (Brummer et al., 2001).
For successful pasture production, cultivars must be tested for grazing tolerance (Brummer and Moore, 2000). The best method to select and evaluate for grazing tolerance is by directly using animals. Mechanical mowers have been used by some researchers, but they "select" passively, i.e., they harvest everything above the height at which they are set and do not contribute damage from hooves and mouths. Animals, on the other hand, harvest selectively (Woledge et al., 1992). Cattle are less selective and less detrimental to white clover than are sheep (Evans et al., 1992) and rotational stocking is less harmful than continuous stocking (Sheath and Hodgson, 1989). Thus, it is possible to select the level of defoliation pressure by manipulating the animals and management used. Bouton et al. (1991) showed that grazing-tolerant alfalfa cultivars could be selected by intense grazing by cattle. Morphological and physiological traits are often radically different for high-performing pasture cultivars vs. high-performing hay-type cultivars (Stapledon, 1928; Jenkin, 1943; Breese and Tyler, 1986). Further studies showed that several morphological and physiological traits were associated with alfalfa grazing tolerance (Brummer and Bouton, 1991, 1992). Further research on traits and selection methodology is needed for other species. Regional collaboration will be an essential requirement for the evaluation and development of cultivars adapted to relatively new management systems, such as intensive, rotational grazing.
Persistence of forage stands for more than 2 or 3 years is a major problem limiting use of several productive, high quality species, such as red clover (Smith and Kretschmer, 1989), birdsfoot trefoil (Miller et al., 1983), and several ryegrass species (Casler, 1988; Casler and Walgenbach, 1990). The ability of a plant or stand to persist for many years is governed by its resistance or tolerance to a multitude of stresses, both biotic and abiotic. Sometimes, improvements in resistance or tolerance to one stress factor can result in significant improvement in stand longevity (see review by Smith and Kretschmer, 1989). Persistence of some species has been improved by selection for survival in harsh environments (Casler, 1988; Consigli, 1991). However, more work needs to be conducted to determine the specific traits responsible for genetic improvement of persistence (Casler, 1988). For some species and for some stresses, research is still required to identify appropriate selection criteria and methodologies.
In the private forage breeding sector of the U.S., selection for increased disease resistance is a major component of alfalfa cultivar development programs, but very limited work on diseases is conducted on other forage crops (Brummer and Moutray, 1996). In birdsfoot trefoil, Fusarium wilt has been implicated in stand losses in NY and MN (Gotlieb and Dorski, 1983; Murphy et al., 1985; Tillapaugh, 1995; Ehlke and Samac, pers. comm). Although Hill and Zeiders (1987) improved resistance to Fusarium wilt in a birdsfoot trefoil population, no resistant cultivars have been released until recently when Pardee trefoil was released as a result of NE-144 research. Mycoleptodiscus terrestris, first identified by Gerdemann (1953), has been isolated from forage legumes in MO (Pettit et al., 1966, 1969), eastern USA (Carroll and Whittington, 1991), and WI (C.R. Grau and R R. Smith, pers. comm., 1994). The root-lesion nematode (Pratylenchus penetrans) causes serious damage to birdsfoot trefoil in Nova Scotia and other regions of North America (Willis et al., 1976). A host of disease problems exist on the forage grasses as well (Braverman, 1986). In order to adequately develop widely adapted cultivars of forages that incorporate resistances to a range of pathogens, collaboration among public sector researchers is clearly needed.
Lack of winterhardiness is a particular problem in the northcentral United States and Canada. If the cultivated germplasm of a given species does not have sufficient cold tolerance or winterhardiness, wild or unimproved germplasm often does. Medicago sativa subsp. falcata, yellow-flowered alfalfa from Siberia, and Russian collections of orchardgrass are sources of winterhardiness for these species (Barnes et al., 1977; Kalton, pers. comm.). Because selection for cold hardiness requires harsh winters, the intensity of selection will vary year to year at any location. For material from areas where cold winters are not common, selecting in more northerly areas may result in greater gains in winterhardiness.
Ideas relating to improved forage quality have changed as animal nutritionists have learned more about the complexities of nutrition. Protein is considered one of the major contributions of most legumes to animal nutrition if the forage is managed and stored correctly. Protein concentration is highly heritable and can be improved readily by breeding (Clements, 1969; Phillips et al., 1982; Coors et al., 1986). Perhaps a more important objective is to alter the proteins in forage legumes to make them more resistant to rumenal degradation (i.e., increasing 'bypass protein') so that nitrogen is less likely to be lost as ammonia (Broderick and Buxton, 1991). Skinner et al. (1994) found variability among alfalfa germplasm sources for protein degradability. Alternatively, plant protein utilization could by improved by increasing the amount of rapidly degraded carbohydrate in the forage so that energy would not be limiting to rumen microbes (Stokes et al., 1991a, b). Pectic polysaccharides represent a potential source of rapidly degraded carbohydrates (Gradel and Dehority, 1972; Van Soest, 1982, 1995), and a significant portion of the total structural polysaccharides in forage legume cell walls are pectic materials (Titgemeyer et al., 1991; Hatfield, 1992). Hatfield and Smith (1995) measured the concentration of uronosyls, pectic sugars and pectin in leaf and stem walls of alfalfa, red clover, and birdsfoot trefoil and found significant differences among and within species. Another means to increase available carbohydrates is to increase digestibility of fiber by breeding for higher ratio of digestible to indigestible fiber. Higher fiber digestibility could maintain total fiber concentration while increasing the availability of carbohydrates in forage. Jung (1996) reported that just small shifts toward more digestible fiber in alfalfa resulted in significant increases in milk production by dairy cows.
Breeding for improved forage quality (small changes in digestibility) in three grass species had a significant positive impact on animal performance and consequently economic returns (Eichhorn et al., 1986; Anderson et al., 1988, Moore et al., 1995). Continued research on divergent selection for forage quality traits in other species, followed by laboratory evaluation and animal performance trials, will be necessary to confirm the animal response to increased forage quality. Buxton and Casler (1993) and Rhodes (1985) concluded there is evidence that lignin and associated phenolics are involved in providing plant resistance to diseases, insects, cold temperatures, and other environmental stresses in various plant species. However, in smooth bromegrass and switchgrass, increased digestibility did not result in changes in forage yield or lodging potential (Vogel et al., 1981; Casler and Ehlke, 1986), despite large reductions in lignin concentration for smooth bromegrass. Fonseca et al. (1999) found no significant correlations between disease resistances and quality constituents, including lignin concentration, in alfalfa. Further research into the structural and nonstructural roles of lignin is warranted. Although increased disease resistance increases forage quality in the presence of the pathogen (Catherall, 1987; Karn et al., 1989), the effects of genetically improved forage quality on pest resistance and stress tolerance are not clearly delineated.
The concept of progeny testing as a selection tool in forage crop breeding has been in existence since the 1890s (Frandsen, 1991). It was refined and put to use by considerable research at numerous breeding stations during the 1950s (see review by Hanson and Carnahan, 1956). Both polycross and testcross procedures have been proposed and compared, on a theoretical basis, with phenotypic selection, which is selection based on individual plant performance per se (Empig et al., 1972; Hill and Haag, 1974). Although empirical comparisons have been made among selection methods for disease resistance in alfalfa (Haag and Hill, 1974; Hill and Leath, 1979), they have not been made for other traits or of other species. Contrary to expectations for traits controlled by some dominant genes, high-performance testers did not differ from low-performance in empirical evaluations of the testcross procedure (Voigt, 1968; Frandsen, 1991). Further research is needed to define the limitations and practical uses of both phenotypic and progeny test selection methods. We also need to use both existing theory and empirical selection studies to improve the efficiency of breeding systems, thereby increasing the rate of genetic progress.
Improved performance by selection within inbred lines has been demonstrated several times in alfalfa. Hybrids or synthetics derived from inbred lines were found to outyield hybrids or synthetics of the respective noninbred parents (Hill, 1975; Rotili and Zannone, 1974; Rotili, 1976). Evidence has been reported that the most efficient way to improve quality of the genes and linkats is the use of selfing assisted by selection (Rotili et al. 1996) and the optimum point of efficacy seems to occur in the second generation of selfing (Rotili, 1992). Pfeiffer and Bingham (1983) reported improvement by selection during inbreeding in tetraploid alfalfa populations. Their best explanation for the genetic improvement was recombination that permitted accumulation of alleles with favourable additive effects over several sexual generations of selection. Early work in the US and Italy indicated that one or two generations of selfing prior to selection improved gain.
In the past decade, molecular markers have become widely used for genetic mapping and breeding methodology studies of agronomic crops (Phillips and Vasil, 2001). Molecular marker work on forages has been scattered among numerous species with little in-depth work on any species other than alfalfa and tall fescue (Phillips and Vasil, 2001; Casler et al. 1996). Molecular markers could be used to augment breeding efforts in two ways: (1) through genetic mapping and marker-assisted selection or (2) through diversity analyses for parental selection or varietal typing. Genetic linkage maps provide a framework for gene localization and open the potential of marker-assisted breeding of both qualitative and quantitative traits. Linkage maps have been constructed in alfalfa (Brummer et al., 1993; Kiss et al., 1993; Echt et al., 1994; Tavoletti et al. 1995), tall fescue (Xu et al., 1995), and eastern gamagrass (Blakey, 1993). Marker facilitated selection, which could be practiced in the seedling year, could greatly speed the forage breeding process. Other molecular marker work has focussed on assessing variability within and among populations (Brummer et al., 1991; Yu and Pauls, 1993; Huff et al., 1993; Kidwell et al., 1994; and Xu et al., 1994) and on varietal identification (Huff, 1996; Barker, 1996). Markers may potentially be useful for the selection of parental plants having alleles that maximize heterosis (Brummer et al., 1994), similar to work on heterotic groups in maize (e.g. Lee et al., 1989) and oilseed rape (Diers et al., 1996). Obviously more work remains to be done to assess the utility of molecular markers to forage breeding projects. Collaborative agreements are essential to enable the wide area testing required to associate markers with phenotypes across several environments. Region-wide cooperation also allows breeders without access to laboratory facilities to interact with others who have molecular marker capabilities.
Evaluate new plant characters and develop germplasm and cultivars with these characters to improve perennial forage species as livestock feed and biofuel uses to enhance rural vitality and promote more secure energy sources.
Build on previous research to evaluate additional breeding methods for improving yield and persistence of alfalfa, red clover, orchardgrass, and other forage species to amke production agriculture mor economical and sustainable.
Evaluate new experimental populations and cultivars of perennial forage species for characteristics necessary for breeders, seed companies, seed and forage producers, and crop consultants to make decisions on commercial use over large regions.
Measurement of Progress and Results
- Release of improved germplasm and cultivars of the following: a. Alfalfa suitable for interseeding and becoming naturalized into depleted pastures and rangelands, b. Alfalfa resistant to the snout beetle, c. Yellow flowered alfalfa that could be used alone under pasture or range conditions or in crosses with purple flowered alfalfa to produce heterosis, d. Alfalfa with multiple mechanisms for resistance to the potato leafhopper, e. Alfalfa with improved tolerance to Al soils, f. Birdsfoot trefoil with enhanced adaptation to the NE-144 members' regions and possessing rhizomes to aid in survival, g. Red clover with adaptability to various areas of north central and northeast US and contiguous areas in Canada, h. Orchardgrass with broad adaptation, high yield, and enhanced persistence, i. Reed canarygrass superior for use as a biofuel crop, j. Timothy with enhanced nutritive value, k. Black medic for use in mixed pastures. These cultivars and germplasms will improve the profitability of forage crops and their development would be impossible without the widespread cooperation facilitated by NE-144.
- Development of improved selection methodologies by evaluating: a. Clonal selection for yield and persistence in alfalfa and orchardgrass, b. Selfed progeny selection for yield and persistence in alfalfa, c. Natural selection for adaptation in red clover, d. Recurrent phenotypic selection on cell wall components in several species.
- Increase in knowledge about the structure of alfalfa populations and the alfalfa genome, specifically, a. Mapping chromosomal regions in alfalfa associated with biomass yield, winter survival, and disease resistance, and b. Evaluation of molecular marker based methods to differentiate among alfalfa cultivars.
- Elucidation of the role of biodiversity on long-term agricultural productivity, using biofuel production as a model system to evaluate grass-grass and grass-forb mixtures versus monocultures.
- Evaluation of new species and germplasms for their persistence under grazing stress to enable more useful recommendations to farmers.
- Output 6. Understanding of the naturalization process of introduced species by studying the attributes of yellow flowered alfalfa that was introduced into South Dakota in the early 20th century. Output 7. Journal papers, technical bulletins, state agricultural experiment station reports, extension bulletins, popular press releases, and web sites describing the research conducted and the enhancements of newly released cultivars and germplasms, and reporting yield data of new forage crop cultivars.
Outcomes or Projected Impacts
- Farmers and ranchers will have access to new cultivars that have improved yield, quality, persistence, grazing tolerance, disease resistance, and other traits designed to enhance their usefulness to the farming enterprise, particularly that of small to medium sized farmers.
- Improved forages will improve farm profitability by providing a more nutritious, more stable feed supply to the dairy and livestock industries; this in turn will increase forage cultivation, lessen the need for grain in rations, and help diversify the farming economy.
- An increase in forage cultivation will have major positive impacts on environmental quality by increasing the proportion of land in perennial crop cover, thereby decreasing erosion, improving soil tilth, adding nitrogen to the cropping system, and improving water quality.
- As a result of this project, breeders will be able to develop new germplasm and cultivars more efficiently and more quickly using newly evaluated breeding methods and molecular markers to move particular chromosomal regions in a targeted manner, while avoiding genetic vulnerabilities that may be present in some germplasm.
- High producing biomass cultivars would be developed from this project that would be essential to make the nascent biofuel industry successful. Given the beneficial environmental characteristics of biofuels, having superior cultivars in hand when the industry is ready is a sensible goal.
- Outcome/Impact 6: Producers will get practical information on which to base their selection of higher yielding and more stable cultivars for their pastures, which will improve grazing systems throughout the region, improving economic welfare for all growers and producers. Outcome/Impact 7: Forage crops that have received limited attention in the past-such as birdsfoot trefoil, black medic, and reed canarygrass--will be evaluated and improved for adaptation (e.g., evaluation of naturalized germplasm) and persistence (e.g., the rhizome trait in trefoil). Outcome/Impact 8: The utility of ecological experiments relating biodiversity and biomass productivity will be empirically tested using biofuel crops as a model system. The importance of species mixtures to ensure long-term productivity must be evaluated. This will be an important verification of the relevance of ecological experiments to applied agricultural situations. Outcome/Impact 9: The characteristics associated with invasive or introduced species will be elucidated by close examination of an introduced alfalfa population that has been expanding its range in western South Dakota over the past decade. A better understanding of what makes species successful invaders will help manage inadvertent introductions more effectively. Outcome/Impact 10: The utility of molecular markers to both develop and describe forage populations and germplasm will be tested. Though these technologies have significant potential, their usefulness in outcrossing, polyploid forage crops like alfalfa is not well tested. Application of these technologies to the ongoing breeding programs of NE-144 participants will help gauge the possible efficiencies they can provide to the development of improved cultivars.
Milestones(2):ermplasm and cultivars will be released and articles published periodically throughout duration of the project. In addition, yield data will be reported annually. Specific milestones are listed below. 2002 Milestones: Identification of an orchardgrass population with suitable broad adaptability. L. corniculatus X L. uliginosus population increased for seed availability. Cycle 2 selection at the S1 and S2 levels.
(3):stablishment of orchardgrass clonal material at four locations. Development of a genetically diverse starting population of red clover. Seed of L. corniculatus X L. uliginosus and ARS-2622 are distributed to cooperators. Initial cross of potato leafhopper resistant alfalfa populations. Initial testing of Al tolerant alfalfa germplasms.
(4):dentification of clones to use in constructing orchardgrass synthetics. Cycle 1 selection of potato leafhopper resistant alfalfa populations.
(5):roduction of an orchardgrass synthetic. Selection of adapted red clover clones. Initial evaluation of black medics. Initial evaluation of first set of falcatas. Cycle 2 selection of potato leafhopper resistant alfalfa populations. Produce Syn. 2 seed of populations derived from two cycles of selection for the breeding methods study.
(6):roduction of orchardgrass clones for a second cycle of selection. Evaluation and selection of L. corniculatus X L. uliginosus. Cycle 3 selection of potato leafhopper resistant alfalfa populations.
(7):evelopment of red clover diallel crossing populations. 2008: Release of black medic germplasms. Initial QTL maps of alfalfa made. Seed increase of L. corniculatus X L. uliginosus germplasm. Nursery testing of potato leafhopper resistant alfalfa populations. 2009: Initial evaluation of second set of falcatas. 2010: Identification of superior orchardgrass parents from the second cycle of selection. Evaluation of red clover populations at each site. 2011: Yield testing of potato leafhopper resistant alfalfa populations. 2012: If necessary, backcross potato leafhopper resistance into an adapted alfalfa background. 2013: Possible release of alfalfa with multiple potato leafhopper resistant mechanisms. 2014: Release of improved orchardgrass synthetic with broad adaptability. 2015: Yield testing of Al tolerant alfalfa germplasm. 2016: Release of improved falcata populations. 2017: Release of improved Al tolerant alfalfa germplasm.
Projected ParticipationView Appendix E: Participation
Performance results will be available in various forage variety trial results published by several states. Normal information transfer via the extension component of the land-grant institutions will be utilized. In cooperation with extension personnel, field days will be conducted to showcase the qualities of new germplasm and cultivars and to describe the various benefits. The primary goal of some evaluations is to provide information to producers about which cultivars and/or species are most useful to their hay and grazing systems. Information will be distributed through university extension bulletins, popular press articles, and field days within each participating state.
Research findings will be disseminated through refereed publications, non-refereed but peer reviewed publications, and abstracts or meetings. International conferences will also provide an outlet for research findings. Germplasms and cultivars will be released by cooperating institutions. Some states already have interactions with seed companies who produce and market seed of public cultivars. Forage breeders across North America and the world will be notified about germplasm releases via articles in Crop Science.