Thomas A. Jones

Breeding Improved Grasses for Semiarid Rangelands

Vast areas of semiarid rangelands in western USA are severely degraded and infested with troublesome weeds such as cheatgrass (Bromus tectorum) and medusahead rye (Taeniatherum asperum). Reseeding with appropriate plant materials that are adapted to the site and competitive enough to replace existing undesirable vegetation is often the most plausible way to reclaim such sites. Unfortunately, many of our native grasses are more difficult to establish and are not as competitive with these exotic weedy grasses as their introduced counterparts, including crested and Siberian wheatgrass (Agropyron cristatum, A. desertorum, and A. fragile). Most native grasses did not evolve under intense management or in association with species as competitive as cheatgrass. Genetically improved germplasms and cultivars of native and introduced (naturalized) grasses have been and are being developed by the Forage and Range Research Laboratory (FRRL) of the United States Department of Agriculture-Agricultural Research Service (USDA-ARS) in cooperation with the Utah Agricultural Experiment Station (UAES) and other agencies. These plant materials have demonstrated the potential for increasing the genetic diversity, protecting watersheds and soil resources, and improving the habitat and grazing potential for livestock and wildlife on semiarid rangelands. Research is also in progress at FRRL to develop germplasm and methodology whereby introduced grasses may be used in combination with natives, and in some instances assist in the establishment of native stands. The proper choice of plant materials must be based on objective criteria if we are to protect our lands and natural resources from further degradation.

Cattle prefer endophyte-free robust needlegrass.

Robust needlegrass (Achnatherum robustum [Vasey] Barkw. = Stipa robusta [Vasey] Scribn.) is a high-biomass rangeland species that is adapted to warmer temperatures and matures later than most cool-season grasses. However, it has been associated with negative animal effects including avoidance. We compared populations of Neotyphodium and P-endophyte-infected endophyte-infected (E+) and endophyte-free (E-) robust needle-grass for animal preference. Leaf blades were fed to yearling heifers in 3 trials of 8-min cafeteria sessions for 4 to 5 days each. Trial 1 (27-30 May) compared E+, E-, basin wildrye (Leymus cinereus [Scribn. &Merr.] A. Love), and tall wheatgrass (Thinopyrum ponticum [Podp.] Barkw. &D.R. Dewey). Basin wildrye consumption (425 g) did not differ from tall wheatgrass (342 g), but basin wildrye consumption exceeded E- (258 g), which in turn exceeded E+ (117 g) (16 animal-sessions). Basin wildrye was dropped from Trial 2 because its consumption exceeded that of both E- and E+. In Trial 2 (1-5 June), consumption of E-, E+, and tall wheatgrass did not differ. Tall wheatgrass was dropped from Trial 3 to allow direct comparison of E- and E+. In Trial 3 (13-17 July), consumption of E- (585 g) exceeded E+ (145 g) (15 animal-sessions). In Trial 3, animals often rejected E+ forage before tasting. Discrimination against E+ was greater at the end of Trial 3 than at the beginning. The reputation of robust needlegrass for animal avoidance may be more related to its endophyte infection status than to the grass itself. Differences in forage-quality parameters were not large enough to account for the observed differences in preference. Ergot and loline alkaloids were not found in either E- or E+, therefore they cannot be responsible for the observed avoidance of E+. Non-trace amounts of ergot alkaloids were found only in seed collected in the Sacramento Mountains of New Mexico and not at other locations in New Mexico, Arizona, or Colorado. DOI:10.2458/azu_jrm_v53i4_jones

Physiological and Morphological Characterization of Basalt Milkvetch (Astragalus filipes): Basis for Plant Improvement

Abstract Astragalus filipes Torr. ex A. Gray (basalt milkvetch or threadstalk milkvetch) is a legume that is widely distributed in western North America and holds promise for revegetation and restoration programs in the western United States. Seed of 67 accessions was collected in 2003 from Utah, Nevada, Idaho, Oregon, California, and Washington. Field-collected forage samples from these accessions had nondetectable or low levels of selenium, swainsonine, and nitrotoxins. Accessions were evaluated at Providence and Millville in northern Utah in 2005 and 2006. At Providence accessions from north-central Oregon exhibited comparatively high biomass yield in summer and fall during both years. Basalt milkvetch accessions with low biomass generally had high crude protein concentration. Acid-detergent fiber and neutral-detergent fiber were positively correlated with biomass yield (r = 0.42, P < 0.0001; r = 0.57, P < 0.0001, respectively). At Millville accessions from north-central Oregon exhibited comparatively high biomass and seed yield. Seed weight per 100 seeds varied among basalt milkvetch accessions in both years at Millville. Plants at Millville treated with imadicloprid insecticide had greater seed yields than nontreated plants in 2006, but not in 2005. When averaged across sites and years, a high correlation between number of stems and biomass (r = 0.82, P < 0.0001) indicated that number of stems is a reliable predictor of high biomass and seed yield. Principal component analysis of seven consolidated plant traits identified two principal components that accounted for 60% and 15% of the variation among accessions. The first principal component was negatively correlated with elevation (r = −0.71, P < 0.01) and positively correlated with latitude (r = 0.46, P < 0.01). The second principal component was positively correlated with elevation (r = 0.36, P < 0.01) and negatively correlated with latitude (r = −0.47, P < 0.01). These results are beneficial in identifying basalt milkvetch accessions that hold promise for plant improvement efforts.

Characterization of diversity among 3 squirreltail taxa

Squirreltail (Elymus elymoides, E. multisetus) is a complex of 5 taxa whose systematic interrelationships are uncertain. Our objectives were to determine whether the 3 taxa studied here, Elymus elymoides ssp. elymoides, E. elymoides ssp. brevifolius, and E. multisetus, can be distinguished by several ecological and physiological traits and whether geographical origin is correlated with these traits across accessions within taxa. A multivariate principal component analysis of materials collected in the 10 contiguous western states successfully distinguished taxa, but no pair of the 3 taxa appeared to be more ecologically similar than any other pair. Elymus elymoides ssp. elymoides, which prevails in the semi-arid cold desert, was shortest and exhibited the lowest total plant dry-matter, earliest phenology, and lowest seed mass. Elymus elymoides ssp. brevifolius, which prevails in the Rocky Mountains, exhibited slowest emergence, highest specific root length, lowest nitrate reductase activity, and lowest root-to-shoot ratio. Elymus multisetus, which is most common in areas with relatively warm springs, exhibited fastest emergence (particularly from deep seeding), greatest root length, and greatest root-toshoot ratio. Elymus elymoides ssp. brevifolius accessions clustered into 3 groups: late-maturing high-seed mass accessions originating in Colorado, New Mexico, and Arizona (Group A), earlymaturing low-seed mass accessions originating in Colorado and Utah (Group B), and intermediate-maturing low-seed mass accessions originating in the Snake River Plain of southern Idaho (Group C). The ecologically distinct subspecies and groups within ssp. brevifolius are indicative of the highly ecotypic nature of the squirreltails, suggesting that restoration practitioners should match site with genetically and ecologically appropriate plant material for these species.

Immature Seedling Growth of Two North American Native Perennial Bunchgrasses and the Invasive Grass Bromus tectorum

Abstract Pseudoroegneria spicata (Pursh) A. Löve and Elymus wawawaiensis J. Carlson & Barkworth are two native perennial grasses widely used for restoration in the Intermountain West. However, the rapid establishment and spread of Bromus tectorum L., an invasive annual grass, has led to a decline in the abundance of native perennial grasses. Proliferation of B. tectorum has been attributed to its early germination, superior cold-temperature growth, profuse root production, and high specific leaf area (SLA). To enhance restoration success, we compared B. tectorum to commercially available plant materials of two perennial rangeland bunchgrasses, P. spicata (cv. Whitmar, cv. Goldar, and Anatone Germplasm) and E. wawawaiensis (cv. Secar), for germination, seedling morphological traits, and growth rates at the immature seedling stage. We monitored germination and immature seedling growth in a growth chamber in two separate experiments, one under low (5/10°C) and the other under high (15/20°C) day/night temperatures. Compared to the average of the two perennials, B. tectorum was 93% (77%) greater at high (and low) temperature for root∶shoot length ratio, but only 14% (14%) greater for root∶shoot biomass ratio and 12% (19%) lower for SLA. This suggests that B. tectorums substantial investment in surface area of roots, rather than in shoot length, root biomass, or leaf area, may be responsible for the annuals success at the early seedling stage. Compared to E. wawawaiensis, P. spicata averaged 65% (41%) higher shoot biomass, 39% (88%) higher root biomass, and 70% (10%) higher absolute growth rate, but 25% (15%) lower SLA and 15% (36%) lower specific root length (SRL) at high (and low) temperatures, respectively. Although P. spicatas greater productivity may initially make for better seedling establishment than E. wawawaiensis, it may also prove disadvantageous in competitive or highly resource-limited environments where high SLA or SRL could be an advantage.

Genetic structure of Eurasian and North American Leymus (Triticeae) wildryes assessed by chloroplast DNA sequences and AFLP profiles

Leymus is a genomically defined allopolyploid of genus Triticeae with two distinct subgenomes. Chloroplast DNA sequences of Eurasian and North American species are distinct and polyphyletic. However, phylogenies derived from chloroplast and nuclear DNA sequences are confounded by polyploidy and lack of polymorphism among many taxa. The AFLP technique can resolve phylogenetic relationships between closely related species, with a curvilinear relationship expected between the proportion of shared bands and nucleotide substitution rate (D), up to about 0.100 D. The objective of this study was to compare D and phylogenetic relationships among 16 Leymus taxa, based on chloroplast DNA sequences and multi-locus AFLP genotypes. Estimates of chloroplast D between taxa were 0.002 and 0.013 within and among continental regions, respectively. Estimates of AFLP D between taxa were 0.076 and 0.093 compared within and between continental regions, respectively, versus 0.024 within taxa. Bayesian and neighbor-joining cluster analyses effectively separated all AFLP genotypes by species, but showed that North American L. ambiguus is a hybrid species with nearly equal contributions from sympatric L. cinereus and L. salinus taxa. Two hierarchical AFLP clades, containing six North American taxa and four Eurasian taxa, had more than 98% bootstrap confidence with 0.071 and 0.055 D among taxa. Three other Eurasian taxa clustered with 79% and 89% confidence, with up to 0.79 D between taxa. These estimates provide benchmarks for phylogenetic comparisons of AFLP profiles, but three taxa could not be reliably grouped, which may reflect concurrent radiation of multiple lineages or lack of homologous AFLP characters caused by a high D.

Bluegrass billbug feeding response to perennial triticeae grasses.

In a 4-year field study, 25 perennial triticeae grasses, representing a wide range of genomes and genome combinations, were evaluated as potential hosts for the bluegrass billbug (Sphenophorus parvulus Gyllenhal [Coleoptera: Curculionidae]). Root-sample data suggested that Russian wildrye (Psathyrostachys juncea [Fischer] Nevski) was unsuitable for billbug reproduction. Numbers of immatures varied significantly among remaining entries. Rhizomatous entries were more tolerant of billbug injury than caespitose entries. Plant mortality rates were frequently 50% or higher for self-pollinated caespitose entries with the SH genome complement (Elymus spp.). Losses to billbugs among the remaining species, particularly those with the J, N, and P genomes, were insignificant. Billbugs did not discriminate between native and introduced grasses, as resistant and susceptible entries were identified in both groups. The results obtained here may aid in selecting triticeae grasses for reseeding in areas where billbugs have damaged stands in the past.

A History of Plant Improvement by the USDA-ARS Forage and Range Research Laboratory for Rehabilitation of Degraded Western U.S. Rangelands

On the Ground Climate change models for the western United States predict warmer winters in the Great Basin and hotter, drier summers in the Mojave Desert, increasing the already high rate of rangeland and pasture degradation, which in turnwill increase annual grass invasion, escalate wildfire frequency, and reduce forage production. These changes in western U.S. rangelands will continue to result in the emergence of novel ecosystems that will require different and/or improved plant materials for successful revegetation. Traditional plant improvement of native and non-native rangeland plant species by the USDA, ARS Forage and Range Research Laboratory (FRRL, Logan, Utah) has been accomplished through rigorous evaluation of seed collections followed by recurrent selection and hybridization of unique plant types within selected populations to identify plants with superior establishment and performance characteristics. After such plant types have been selected, they are further evaluated in multiple ecologically diverse locations to identify broadly adapted superior germplasm for public release. Plant improvement of perennial grasses, legumes, and forbs by the FRRL has provided and will continue to deliver plant materials that support sustainable rangeland management efforts to service productive and functionally diverse rangelands.

Identifying Geographically Based Metapopulations for Development of Plant Materials Indigenous to Rangeland Ecosystems of the Western USA

Rangeland ecosystems account for about half of the earth’s land surface. They play an important role in providing forage for livestock and wildlife, and they serve as critical watershed areas. Many of the world’s rangelands have been degraded by overgrazing, marginal crop production, mineral and energy extraction, recreation, and other human-caused disturbances. This degradation has led to invasion by exotic weeds and subsequent increases in fire frequency. This, in combination with uncertainties associated with global climatic change, has resulted in a critical need for plant materials to restore and revegetate rangeland ecosystems. The assessment of genetic variation and its phenotypic expression in important rangeland plant species (especially forbs) is critical in defining population structures (genetically differentiated groups) that could be used in rangeland restoration/revegetation efforts. We used common-garden studies and DNA-based analysis of genetic variation to assess genetic diversity in three rangeland legume species indigenous to rangeland ecosystems of the Great Basin Region of the western USA. Results of these studies are presented as three case studies that describe data collection procedures, analysis, and interpretation used to identify population structures in each species. These data formed the basis for combining plant collections into geographically based metapopulations for these three legume species that are being used to develop plant materials for commercial seed production and subsequent use on rangelands of the Great Basin.