Planting native species after a major disturbance is a critical tool land managers use to stabilize soils, restore ecosystem processes, and prevent weed invasion. However, within the sagebrush steppe and other arid and semi-arid environments the percentage of sown seeds that produce an adult plant is remarkably low. Applying fertilizers at the time of planting may improve native plant establishment by increasing the ability of the seedlings to cope with environmental stresses. However, traditional fertilizer applications are often economically infeasible and may be counterproductive by encouraging weed invasion. Seed coating technology allows for the efficient application of fertilizers within the microsite of the seeded species. The objective of our research was to determine the optimal rate of fertilizer to apply to the seed to improve seedling emergence and plant growth. We applied a phosphorus (P) rich fertilizer (0.13 g P g-1) to bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) Á. Löve) seeds in a rotary coater at rates ranging from 0 to 50 g of fertilizer 100 g-1 seed. Three separate studies were conducted to test germination, biomass, relative growth rate, and tissue nutrient uptake. Study one showed decreasing root and shoot biomass and increasing time to 50% germination as fertilizer rates increased. Study two showed no difference in relative growth rate between the controls and fertilizer treatments. Study three showed no difference in root and shoot biomass or nutrient concentration between treatments except in the lowest fertilizer treatment (10 g fertilizer 100 g-1 seed), which was significantly lower in root and shoot biomass than all other treatments but had higher P tissue concentrations than all other treatments. Collectively these results showed no evidence that a P fertilizer coating could aid in bluebunch wheatgrass seedling establishment. Because bluebunch wheatgrass and similar late-seral plants have evolved with low nutrient requirements they may not be physiologically capable of handling increased nutrient supply, which may explain the results of our studies. Continued studies and fieldwork need to be performed to evaluate the potential of fertilizer seed coatings in restoration efforts.

Fairway crested wheatgrass, which is identified taxonomically as Agropyron cristatum (L . ) Gaertn. (45 ), A. cristatiforme (38) , or A. pectiniforme Roem. and Schult (22), is an economically important range grass belonging to the "crested wheatgrass complex" (24, 38). The crested wheatgrass complex includes diploid, 2n = 14, tetraploid, 2n = 28, and hexaploid, 2n = 42, forms (1, 11, 22). The variety Fairway and Fairway-like derivatives are the only known diploid members of the species complex (24, 38). Meiotic chromosome behavior of Fairway diploids appears to be typical of other diploid species; however, the number of plants examined cytologically has been relatively small. Although Fairway crested wheatgrass is a good seed producer, interplant variation in fertility is high (13, 22, 25, 42). Irregular chromosome behavior is a common source of sterility and may be contributing to the variable seed set in diploid crested wheatgrass. No information is available concerning the relation of meiotic chromosome behavior to fertility in Fairway crested wheatgrass. Polyploid crested wheatgrasses are generally considered to be of autoploid origin, i.e., they are derived by duplication of the chromosome complement of a diploid prototype. Chromosome pairing in the polyploid species (31), in interspecific hybrids (12), and in polyhaploid plants (11) substantiate the autoploid derivation of polyploid crested wheatgrass. Diploid and tetraploid forms of crested wheatgrass have been hybridized by Knowles (24), and chromosome pairing in the hybrids suggest a close relation between the diploid and tetraploid genomes. Colchicine-induced tetraploids of Fairway crested wheatgrass have been produced by Knowles, 1 and these artificial tetraploids are currently being utilized in his crested wheatgrass breeding program. If the full breeding and cytogenetic potentials of diploid crested wheatgrass are to be realized, the meiotic chromosome behavior and the cytotaxonomic status of this species must be fully understood. The present investigation was designed to provide further information concerning the cytogenetic characteristics of Fairway crested wheatgrass and its autotetraploid derivatives. This investigation was established with the following objectives: 1. To examine meiotic chromosome behavior of Fairway crested wheatgrass. 2. To determine the relation of meiotic chromosome behavior to fertility in Fairway crested wheatgrass. 3. To evaluate the effectiveness of several colchicine treatments in doubling the chromosome complement of Fairway crested wheatgrass. 4. To determine the effect of induced polyploidy on plant morphology in colchicine-induced tetraploids of Fairway crested wheatgrass. 5. To determine the meiotic chromosome behavior and fertility of induced tetraploids of Fairway crested wheatgrass.

Aboveground biomass, litter biomass and root biomass of a crested wheatrgrass (Agropyron desertorum [Fisch.] Schult.) dominated community were inventoried in the fall of 1971, 1972, and 1973. In addition, energy, nitrogen, fats and ash determinations were made on the materials collected in 1972 and 1973. The sampling methods used generated data sufficiently precise to detect significant differences (α = .10) among biomass components among years. The chemical contents of the components were similar in the fall of 1972 and the fall of 1973 despite the large differences in growing season precipitation. A simple linear regression formula was generated from which aboveground biomass was predicted using individual plant volume as the independent variable. Regression techniques were tried in an effort to use aboveground biomass to predict root and litter biomass. This approach proved unsuccessful because of high variability within the data. Changes in the biomass of the components were analyzed with respect to differing precipitation regimes. Aboveground biomass responded positively and linearly to increasing growing season precipitation. Litter biomass decreased as current growing season precipitation increased. However, litter increased as a function of increasing previous-growing-season precipitation. Root biomass decreased with increasing previous-growing-season precipitation. It was found that both litter:shoot and root:shoot ratios decreased as a function of increasing growing season precipitation.

During 1980-81, studies with crested wheatgrass (Agropyron desertorum) and fourwing saltbush (Atriplex canescens) were conducted in controlled environment growth chambers as well as under field conditions to achieve the following objectives: 1. To determine the effect of nitrogen fertilizer on the water use efficiency. 2. To determine the effects of various temperature, water stress and nitrogen treatments on the productivity, nitrogen content and carbohydrate reserves. 3. To determine the effects of N fertilization on fall and spring regrowth. Crested wheatgrass and fourwing saltbush plants were maintained in three growth chambers for 60 days under three temperature regimes (11/7, 19/7 and 27/7 C), two soil moisture stress regimes (-0.3 bars and -15 bars) and three N fertilizer levels (0, 50 and 100 kg of N/ha). During the study, tranpiration and plant biomass data were recorded. During the first week of September, 1980, crested wheatgrass and fourwing saltbush pastures at Nephi, Utah, were subjected to three nitrogen fertilizer levels (0, 50 and 100 kg N/ha). After 60 days the fall regrowth was clipped. In the first week of June 1981 spring regrowth of both species was measured. In the fall of 1981, a second experiment was laid out at Nephi where crested wheatgrass and fourwing saltbush plants were subjected to three soil moisture regimes (dry, medium and wet) and three nitrogen fertilizer levels. At the end of a 60 day study period, dry matter yield, root distribution, water content and soil samples at different incremental soil depths were collected. Under controlled environment conditions, the water use efficiency of both species was six percent more with the application of a moderate amount of nitrogen (50 kg/ha). A high temperature regime (27/7 C) and a high water stress regime (-15 bars) increased the water use efficiency of plants by eight and six percent respectively. Results of the growth chamber experiment revealed that nitrogen fertilization had a significant effect on plant biomass, nitrogen percent and total nonstructual carbohydrate reserves of crested wheatgrass and fourwing saltbush. The data further suggested that nitrogen fertilization can substitute for the adverse effects of low temperature and low soil moisture on plant growth. Nitrogen fertilization during fall increased plant biomass, nitrogen percent and total nonstructural carbohydrate reserves in crested wheatgrass and fourwing saltbush. Fall fertilization did not reduce spring regrowth. It is inferred that under limited soil moisture and low temperature during the fall growing season, a moderate amount of nitrogen fertilizer (50 kg N/ha) may increase the forage availability and water use efficiency of crested wheatgrass and fourwing saltbush to the level of plants maintained at moderate temperature and adequate soil moisture. Nitrogen fertilization (50 kg N/ha) of crested wheatgrass and fourwing saltbush during fall does not reduce plant nitrogen percent or carbohydrate reserves which may limit spring regrowth.

Crested wheatgrass arrived in North America at the turn of the twentieth century through the foreign plant exploration missions sponsored by the United States Department of Agriculture. During the first two decades of the new century, scientists tested the grass at agricultural experiment stations. They determined it was useful for grazing and particularly valuable because it could grow in drought conditions with little or no care and would continue to produce high quality feed even after several years of heavy use. Beginning in the 1930s federally sponsored land utilization and agricultural adjustment programs sponsored the use of crested wheatgrass for soil conservation and weed control. The grass protected the soil on the land that had been entered into the acreage reserves and the conservation reserves programs of the federal soil bank. Also in the late 1930s and through the 1960s, rangeland managers used crested wheatgrass to improve forage productivity on public lands that were used for grazing. By the 1970s somewhere between 12 and 20 million acres of crested wheatgrass grew in North America in eleven western states, and in Saskatchewan and Alberta. By 1980 attitudes about agriculture and wilderness had changed in the United States and land management was focused on multiple uses and on protecting ecosystems and native species. Attitudes about grazing and agricultural landscapes had changed and many preferred nonagricultural landscapes and land uses. As a result, crested wheatgrass went from being considered one of the most valuable plants in North America to being considered an invasive weed, in some quarters. Debates in the last 25 years have tried to determine if, where, and how crested wheatgrass belongs in North America. This thesis explains the discourses, or interest groups, that are participating in the current conversation. One impulse is to use empirical evidence to determine whether or not introduced plants like crested wheatgrass belong, but the main contention of this thesis is that empirical studies alone will always be insufficient measures because belonging is also a subjective and experientially or emotionally derived measure.

The potential of basin wildrye (Elymus cinereus Scribn. & Merr. 'Magnar') and tall wheatgrass [Agropyron elongatum (Host) Beav. 'Jose '] to establish on saline, arid rangelands in the Great Basin in relation to soil water and salinity was compared in field and laboratory experiments. Tall wheatgrass had higher emergence and establishment on a nonsaline and a saline soil (electrical conductivity of the saturation extract of 7 dS·m-1) over a range of spring precipitation as simulated by sprinkler irrigation. Basin wildrye will require supplemental irrigation to establish on soils of similar salinity. In the absence of precipitation, soil salinity increases and matric and osmotic potentials rapidly decrease as the surface soil dries in late spring. Germination and growth responses in relation to salinity and drought in laboratory experiments were consistent with emergence and establishment results in the field experiments. Tall wheatgrass had higher total germination, rate of germination and radicle growth under decreasing osmotic potentials and higher emergence under decreasing matric potentials than basin wildrye. Tall wheatgrass had greater root and shoot yield than basin wildrye when osmotic potentials in sand cultures were decreased by solutions of NaCl, Na2SO4 and CaCl2.Tall wheatgrass is more tolerant of salt and boron than basin wildrye, but basin wildrye is highly salt tolerant compared to most forage species. Tall wheatgrass had more rapid root elongation and more extensive root growth than basin wildrye seedlings grown in 60-cm soil columns filled with nonsaline and saline soil. Germination and growth of both species was reduced by ions in addition to the effects of water stress due to low osmotic potentials. Rate of germination and radicle growth of both species was less in salts than in isosmotic polyethylene glycol solutions. Seedlings exhibited less growth in saline than nonsaline soil even when plant water stress was minimal or when leaf water potentials were low but turgor was maintained by osmotic adjustment. Germination at low osmotic and matric potentials and root elongation in relation to salinity may be important plant responses to use in evaluating the potential for establishment of new plant materials on saline, arid rangelands.

A field and laboratory study was made to determine the effect of alternate year rest rotation grazin in stem bases and root crowns of crested wheatgrass. Analyses for carbohydrate reserves and total nitrogen were made for the following treatments: (1) exclosures; (2) open range; (3) agronomy cages. Both carbohydrate concentration and total nitrogen content showed differences between sampling dates but did not show differences as a result of grazing treatment on individual dates. Differences between sampling dates were associated with season and growth stage of plants. Although differences due to grazing teatment were not shown for individual dates the combined average carbohydrate concentration for plants rested or protected from grazing for one season was higher than from protected plants inside exclosures or from plants grazed during the study. Despite the short duration of this study these results indicate that alternate year rest rotation grazing as practiced on Diamond Mountain is not adversely affecting storage of food reserves in crested wheatgrass.

Crested wheatgrass (Agropyron cristatum [L.] Gaertn.) is one of the most commonly seeded grass species in the western United States and dominates thousands of hectares in the Great Basin. Although many degraded Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) plant communities have been seeded with crested wheatgrass, successional pathways, influence of soil attributes, and cultivation history on the vegetation of these communities have not been fully characterized. I sought to identify community phases, vegetative differences, and soil attributes that explain variation among 35 Wyoming big sagebrush communities historically seeded with crested wheatgrass. All communities were more than 30 years old and had not experienced fire, or received subsequent chemical or mechanical treatments following their original seeding. Species richness, diversity, vegetation cover, and soil samples were measured in four 20 x 5 m intensive Modified Whittaker plots per community. Hierarchical clustering and principal component analysis of three indicator species (crested wheatgrass, Sandberg bluegrass, and Wyoming big sagebrush) identified four distinct community phases. Community phase 1 was dominated by crested wheatgrass and had the lowest species richness and cover of big sagebrush. Phases 2 and 3 had the highest species richness and cover of native species. Phase 4 was dominated by big sagebrush and had the lowest cover of crested wheatgrass. Community phases differed significantly for soil texture, soil nitrogen, and ground cover characteristics. Bare soil was almost double on loam-textured soils and rock cover was higher on clay loam texture soils (P < 0.05) as well as native plant cover. Communities previously cropped occurred on more coarse-textured soils and had 6-fold lower native species cover and double exotic herbaceous and crested wheatgrass cover. Cropping occurred on favorable, low rock, fine-texture soils, the same soils that favor crested wheatgrass production and reduce resilience of native plant composition. Delineation of community phases provided a new, empirically based state-and-transition model, while the characterization of soil attributes and disturbance history provided information about feedback mechanisms influencing dominant species that delineate community phases and effect community structure. This information can be used to assist in the development of management strategies in crested wheatgrass seeded communities.

Two intermediate wheatgrass seedings with different levels of grass bug infestation were evaluated for herbage production, seedhead production, percent dry matter, crude protein, and cell contents. Study sites were located at different elevations on mountain summer ranges in northern (Site I) and central (Site II) Utah. Study plots at Site I and Site II were infested with 113 and 210 bugs per sweep, respectively. Herbage production appeared to be reduced in early spring on the site with the higher infestation; however, no effect on season-long herbage production could be detected on either site. Seedhead production on infested plots was reduced 45 percent at Site I and 56 percent at Site II. No important effect on dry matter content of infested plants was detected even though the leaves appeared to be dry and in a condition of moisture stress. Crude protein of infested plants was significantly higher (one to two percent) than control plants on the site with the higher infestation. The percentage of cell contents of plants on the more highly infested plot was eight percent less than the percentage of cell contents of control plants in the early spring. This reduction coincided with the period of peak damage. Later in the season this difference diminished as plant growth continued after the bug population completed its life cycle.

Thesis (MSc (Genetics))--Stellenbosch University, 2008. / Thinopyrum distichum (2n = 4x = 28; J1dJ1dJ2dJ2d) is a hardy, salt-tolerant maritime wheatgrass indigenous to southern Africa. In order to transfer its salt-tolerance to cultivated cereals, the Thinopyrum chromosomes involved must first be characterized with molecular markers. Thinopyrum distichum chromosomes 2J1d, 3J1d, 4J1d and 5J1d have previously been found to be major determinants of salt-tolerance. A genotype panel consisting of two triticale/Th. distichum allopolyploids, two Th. distichum/2*triticale doubled-haploids, eight triticale addition-lines (for chromosomes 2J1d; 2J1dβ; 3J1d; 3J1dL; 4J1d; 4J2d; 5J1d and 7J2d, respectively) and two triticale translocation-lines (involving chromosome arms 3J1dS and 3J1dL, respectively) were used for fluorescence-based, semi-automated AFLP-analyses and to a lesser extent for EST-SSR microsatellite marker-development, to identify molecular markers specific to the critical Th. distichum chromosomes. Thirteen EST-SSR primer pairs produced four putative Th. distichum-specific microsatellite-markers, one of which was specific for critical chromosome 5J1d. AFLP-analysis with 60 selective EcoRI/MseI and 18 Sse8387I/MseI primer combinations produced 159 AFLP-fragments specific for Th. distichum. These included seven putative markers for chromosome 2J1d, 15 for 3J1d, one marker for 4J1d and two for 5J1d. A salt-tolerance experiment was done to determine which chromosome 2J1d and 3J1d regions may carry genes for salt-tolerance. Plants were selected that had a monosomic addition of a chromosome 2J1d variant (either the complete chromosome or a modified version referred to as 2J1dβ) in addition to one of four chromosome 3J1d variants (the complete 3J1d chromosome; a 3J1dL-telosome; a 3J1dS-translocation or a 3J1dL-translocation). The results suggested that Th. distichum chromosome-arms 2J1dL and 3J1dS are probably involved in salt-tolerance. A group of 93 trigeneric (Triticum/Secale/Thinopyrum) F2 secondary hybrids were then analyzed in order to: (i) Evaluate some (ten) of the newly developed putative AFLP-markers; and (ii) attempt to find translocations, telosomes or substitutions involving the critical Thinopyrum chromosomes. Five (50 %) of the ten putative AFLP-markers could be reproduced, but only four proved to be chromosome-specific. It was also possible to assign hese four markers to chromosome arms: E32M49.118 (2J1dS); E41M49.103 (2J1dS); E35M49.137 (3J1d); and E41M49.188 (3J1dL). The selective primer combination that produced marker E41M49.103 (2J1dS), also amplified a fragment of the same size on chromosome 4J1d. These markers will be useful for further mapping and selection of the salt-tolerance genes. The fact that only four of the ten putative AFLP-markers evaluated proved to be repeatable implies that the remaining untested markers need to be confirmed against larger genotype panels as well. Probable reasons for the relatively low frequency of markers that turned out to be reliable are discussed. The marker-association study also revealed that visual examination of all electropherograms produced by AFLP-fragment analysis is necessary to correctly identify all AFLP-fragments. Use of the AFLP- and STS-/SCAR-markers in conjunction with the group of 93 F2 secondary hybrids showed that 18 of these probably carried a 3J1dL-translocation. Several hybrids possibly had translocations involving the 4J1d and 5J1d chromosomes. However, these results need to be confirmed. Various hybrids also appeared to have critical Th. distichum substitutions, although this still requires further confirmation. The identified plant material could prove useful for further characterization of salt-tolerance in Thinopyrum, and its eventual utilization in cereal crops.