Antonio J. Palazzo

Merits of native and introduced Triticeae grasses on semiarid rangelands

Experiments were conducted on four semiarid range sites to compare stand establishment, productivity, and persistence of several introduced perennial Triticeae grasses with that of their native counterparts. On Intermountain sites with severe water limitations (< 300 mm), native grasses were more difficult to establish, less productive, and less persistent than the introduced grasses. Stands of native grasses declined most rapidly under defoliation. At locations where moisture conditions were more favorable, particularly where more summer precipitation occurred, native Triticeae grasses established and persisted relatively well compared with the introduced entries. Although difficult to establish, stands of the rhizomatous native, western wheatgrass [Pascopyrum smithii (Rydb.) A. Love] in creased during the seasons after establishment. Choice of plant materials to be used in range seeding programs should be based on objective criteria. To do otherwise will perpetuate degradation of soil resources, especia...

Stand Establishment and Persistence of Perennial Cool-Season Grasses in the Intermountain West and the Central and Northern Great Plains

Abstract The choice of plant materials is an important component of revegetation following disturbance. To determine the utility and effectiveness of various perennial grass species for revegetation on varied landscapes, a meta analysis was used to evaluate the stand establishment and persistence of 18 perennial cool-season grass species in 34 field studies in the Intermountain and Great Plains regions of the United States under monoculture conditions. Combined across the 34 studies, stand establishment values ranged from 79% to 43% and stand persistence values ranged from 70% to 0%. Intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D. R. Dewey), tall wheatgrass (Thinopyrum ponticum [Podp.] Z.-W. Liu & R.-C. Wang), crested wheatgrass (Agropyron spp.), Siberian wheatgrass (Agropyron fragile [Roth] P. Candargy), and meadow brome (Bromus riparius Rehmann) possessed the highest stand establishment (≥ 69%). There were no significant differences among the 12 species with the largest stand persistence values. Basin wildrye (Leymus cinereus (Scribn. & Merr.) Á. Löve), Altai wildrye (Leymus angustus [Trin.] Pilg.), slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners), squirreltail (Elymus spp.), and Indian ricegrass (Achnatherum hymenoides [Roem. & Schult.] Barkworth) possessed lower stand persistence (≤ 32%) than the majority of the other species, and Indian ricegrass (0%) possessed the lowest stand persistence of any of the species. Correlations between environmental conditions and stand establishment and persistence showed mean annual study precipitation to have the most consistent, although moderate effect (r = ∼0.40) for establishment and persistence. This relationship was shown by the relatively poor stand establishment and persistence of most species at sites receiving less than 310 mm of annual precipitation. These results will be a tool for land managers to make decisions concerning the importance of stand establishment, stand persistence, and annual precipitation for revegetation projects on disturbed sites.

Selection response for molecular markers associated with anthocyanin coloration and low-temperature growth traits in crested wheatgrasses

Hycrest is an outcrossing tetraploid cultivar of crested wheatgrass developed from a hybrid between an induced tetraploid form of Fairway (Agropyron cristatum) and natural tetraploid Standard (A. desertorum). The CD-II cultivar was selected from cv. Hycrest on the basis of vigorous vegetative growth and green leaf coloration during early spring. This study examines the selection response of molecular markers associated with anthocyanin coloration (AC), growth habit (GH) and other traits in Hycrest, CD-II, and two second-generation polycross (PX2) populations derived from three purple-leaf selections and three green-leaf selections of Hycrest. AC was positively correlated with prostrate GH and inversely correlated with plant height and leaf width in the experimental PX2 populations. Of the 578 AFLP markers surveyed, 13 showed pleiotropic effects on GH and AC in the PX2 populations. In all cases, marker alleles associated with prostrate GH also enhanced AC. Four of these 13 markers also showed large selecti...

Detection of linkage disequilibrium QTLs controlling low-temperature growth and metabolite accumulations in an admixed breeding population of Leymus wildryes

Low-temperature soluble carbohydrate accumulations are commonly associated with anthocyanin coloration, attenuated growth, and cold adaptation of cool-season grasses. A total of 647 AFLP markers were tested for associations with anthocyanin coloration, tiller formation, leaf formation, cumulative leaf length, percent soluble carbohydrate, and dry matter regrowth among replicated clones of an admixed Leymus wildrye breeding population evaluated in low-temperature growth chambers. The admixed breeding population was derived from a heterogeneous population of L. cinereus × L. triticoides F1 hybrids, with two additional generations of open pollination. Two AFLP linkage maps, constructed from two full-sib mapping populations derived from the same F1 hybrid population, were integrated to produce a framework consensus map used to examine the distribution of marker-trait associations in the admixed F1OP2 population. Thirty-seven linkage blocks, spanning 258 cM (13.6%) of the 1895 cM consensus map, contained 119 (50%) of the 237 markers showing at least one possible trait association (P < 0.05). Moreover, 28 (68%) of the 41 most significant marker-trait associations (P < 0.005) were located in 15 QTL linkage blocks spanning 112.9 cM (6%) of the linkage map. The coincidence of these 28 significant marker-trait associations, and many less significant associations, in 15 relatively small linkage blocks (0.6 cM to 21.3 cM) provides evidence of admixture linkage disequilibrium QTLs (ALD QTLs) in this heterogeneous breeding population. At least four of the remaining 13 putative marker-trait associations (P < 0.005) were located in genetic map regions lacking other informative markers. The complexity of marker-trait associations results from heterogeneity within and substantial divergence among the parental accessions.

Chemical Structure of Soil Organic Matter in Slickspots as Investigated by Advanced Solid-State NMR

Slickspot soils are saline, and knowledge of their humic chemistry would contribute to our limited understanding how salinity affects soil C and N stocks. We characterized humic acids (HA) from slickspot soils with solid-state 13C nuclear magnetic resonance (NMR). Expanding on previous use of cross polarization/magic angle spinning (CP/MAS) NMR, we used direct polarization (DP) and yet more advanced spectral editing techniques to identify specific functional groups, detect the connectivities of different functional groups, and selectively observe fused ring carbons. A series of soil HA was extracted from soil layers having different physical properties: silt texture, vesicular structure, and clay texture. They were compared with HA from corresponding depths in soils adjacent to the slickspots. All HA consisted of five main structural components: aliphatic chains, peptides, sugar rings, lignin residues, and aromatics/olefinics. For all soils, except one outside slickspots, the HA from the vesicular and clay layers contained less nonpolar alkyls and more aromatics than those from surface silt layers, but their spectral proportions differed when the 13C NMR was performed using CP/MAS instead of DP. Humic acids from the surface layers inside the slickspots had lower aromaticity than those from outside the slickspots. Advanced spectral editing techniques allowed for the selection of nonprotonated carbons and mobile groups, alkyls, CH, and CH2 groups, which would otherwise be buried in the heavily overlapped spectrum. They provided more structural information than was obtained by routine 13C CP/MAS or DP.

Promoting late-fall establishment of tall fescue with artificial soil covers to minimise soil erosion.

Frequently, turfgrass seedings have been sown in the late fall, which usually results in a poor vegetative stand and the possibility of soil erosion the following spring. This study evaluates the effects of a spun-bonded polyester soil cover placed over a late-fall seeding on subsequent seedling growth and overwintering. Clemfine, Mustang, Rebel, and Rebel II cultivars of tall fescue (Festuca arundinacea Schreb.) were sown on a silt loam soil in late fall (on 17 October in 1989 and 19 October in 1990) and allowed to grow with and without a soil cover until June. In the spring the temperature under the soil cover was greater than 2°C warmer than the uncovered soil from mid-April through May. Over the winter, leaf and root weights showed no detrimental effects from being under the cover. Individual cultivars grown under the cover produced 2 to 11 times greater leaf yields and 38 to 270% better stand establishment than those sown on the exposed soil. However, plant winter injury was observed under the soil cover in small soil depressions which accumulated water originating from thawing. All cultivars had similar amounts of growth under the cover. However, leaf yields for Rebel were 30-55% less than the other cultivars when grown under the cover and this was probably related to a low seed germination rate. The covers also promoted weed growth, which comprised from 34–65% of total leaf weights and was found to be negatively correlated (r = −0.66) to the yields of the sown grass. The soil cover was found to be beneficial to improving the success of seedling establishment of late seedings of tall fescue in cold areas.

Enhancement of Germination and Growth of Slickspot Peppergrass in a New Medium with Two Compost Organic Fractions

Slickspot peppergrass (Lepidium papilliferum) is an herbaceous biennal or possibly perennial “rare” endemic plant of the southwestern Idaho high desert listed as a threatened species. This plant establishes perennial seed banks, with seeds remaining dormant and viable for several years. This study aimed to enhance the germination and early growth of this plant by adopting a new medium, a nutrient-enriched agar solution, also added with humic acid (HA) and water-extractable organic matter (WEOM) fractions isolated from a green compost (GC) and a mixed compost (MC). The germination percentage of slickspot peppergrass in this new medium was much greater than that obtained in previous studies. Further, the addition of GC-HA in the medium enhanced significantly the germination and early growth of this plant. The addition of GC-WEOM and MC-WEOM were beneficial only on plant growth for at least 7 months.