Hordeum brachyantherum

About: Hordeum brachyantherum is a research topic. Over the lifetime, 30 publications have been published within this topic receiving 598 citations.

Patterns of invasion within a grassland community

Abstract: Summary 1 Relatively few studies have looked for patterns of invasion by non-native species within communities. We tested the hypotheses that: (i) some types of microhabitats within a community are more invasible than others; (ii) microhabitat types that differ in invasion also differ in resource availability; and (iii) invasibility is mediated by effects of these resources on competition between native and non-native species. 2 To test the first two hypotheses, we measured plant cover and soils in a coastal grassland in northern California. Consistent with these hypotheses, cover of non-native plants was consistently high where nitrogen-fixing shrubs had recently grown, in the bottoms and sides of gullies and on deep soils, and these microhabitats tended to have relatively high nitrogen or water availability. 3 Cover and number of native species tended to be lower where cover of non-native species was higher, indicating that non-native species as a group negatively affected native species. However, the number of non-native species also tended to be lower where the total cover of non-natives was higher. This suggests that a few non-native species excluded natives and other non-natives alike. 4 To test the third hypothesis, we grew a common non-native, the annual grass Lolium multiflorum, and a common native, the perennial grass Hordeum brachyantherum, at different levels of water and nitrogen. The relative competitive ability of the native was higher at lower nitrogen availability but not at lower water availability. When 10-week-old native plants were grown with non-native seedlings and nitrogen was relatively low, the native out-competed the non-native. However, the non-native out-competed the native at all resource levels when species were both grown as seedlings. Competition between native and non-native grasses in this system may thus help prevent invasion by non-natives in microhabitats where nitrogen availability is low, but invasion may be relatively irreversible.

Restoring native perennial grasses to rural roadsides in the Sacramento Valley of California : Establishment and evaluation

Abstract: Along rural roadsides of the Sacramento Valley of California, we seeded native and non-native perennial grasses to gauge their potential value in roadside vegetation management programs. In trial I (polycultures), three seeded complexes and a control (resident vegetation only) were tested. Each seeded plant complex included a different mix of perennial grasses seeded into each of several roadside topographic zones. The seeded levels of plant complex were: native perennial grasses 1 (8 species); native perennial grasses 2 (13 species); and non-native perennial grasses (3 species). In trial II, plots were seeded to monocultural plots of 15 accessions of native Californian and three cultivars of non-native perennial grasses. Plots in both trials were seeded during January 1992 and evaluated for three successive years. In trial I polycultures during 1993, canopy cover by seeded species was not significantly different among the three seeded complexes. The three seeded complexes showed statistically equivalent reduction of canopy cover by resident plant species. Biomass of seeded perennial grasses was greater for non-native perennial grasses than for native perennial grasses 1 or native perennial grasses 2. Total biomass (seeded plus resident species) was greatest for non-native perennial grasses. In trial II monocultures during 1993, the non-native Thinopyrum intermedium ssp. trichophorum (pubescent wheatgrass) attained the greatest height, followed by the native species Nassella (Stipa) cernua (nodding needlegrass), Nassella (Stipa) pulchra (purple needlegrass), and Elymus trachycaulus var. majus (slender wheatgrass). By contrast, the non-native Festuca ovina (sheep fescue) and the native Poa secunda ssp. secunda (pine bluegrass) were particularly short. N. cernua, N. pulchra, E. trachycaulus, and T. intermedium ssp. trichophorum showed particularly great canopy cover, whereas particularly low values of canopy cover were obtained for F. ovina and P. secunda ssp. secunda. A highly significant inverse linear relationship was obtained by regression analysis when canopy cover for seeded perennial grasses was used to predict canopy cover for resident plant species (p < 0.0001, r 2 = 0.297, slope = -0.336, intercept = 39.442). In 1994, the following native perennial grasses showed substantial canopy cover in trial II monocultures and appear promising for use in Sacramento Valley rights-of-way: Bromus carinatus (California brome), Elymus glaucus (blue wildrye), E. trachycaulus, all accessions of Hordeum brachyantherum ssp. brachyantherum (meadow barley), a prostrate accession of Hordeum brachyantherum ssp. californicum (California barley), N. cernua, and N. pulchra. In addition, the non-native T. intermedium ssp. trichophorum performed well. By contrast, virtual failure of stands was observed for the non-native F. ovina and the following native species: Elymus multisetus (squirreltail), two accessions of Festuca idahoensis (Idaho fescue), Festuca rubra (creeping red fescue), and P. secunda ssp. secunda.

Molecular phylogeny of the genus Hordeum using three chloroplast DNA sequences

Abstract: The genus Hordeum consists of three cytotypes (2x, 4x, and 6x). Its reproductive isolation has been incomplete between closely related species and hence the genetic relationship is reticulate and complex. We used 32 taxa of Hordeum and three chloroplast DNA sequences, matK, atpB–rbcL, and trnL–trnF, in the current study. Molecular phylogenetic analysis based on sequence data of the three chloroplast DNA regions clearly demonstrated genetic relationships among taxa and origin of polypoids. The formation of H. secalinum likely involved hybridization between Hordeum marinum subsp. marinum and a Eurasian diploid possessing the H genome. The formation of hexaploid Hordeum brachyantherum involved hybridization between tetraploid H. brachyantherum and diploid H. marinum subsp. gussoneanum. The formation of three tetraploids, H. brachyantherum, Hordeum jubatum, and Hordeum guatemalense, probably involved hybridization between H. brachyantherum subsp. californicum and an altered H genome diploid. The formation of ...

Effects of various pollens on development, survivorship, and reproduction of Euseius tularensis (Acari : Phytoseiidae)

Abstract: Effects of 17 different plant pollens on the development, survivorship, and reproduction of the predacious mite Euseius tularensis (Congdon) were studied in the laboratory. Mites fed cattail, Typha latifolia L.; ice plant, Malephora crocea (Jacquin); and five different types of commercially available tree pollens (apple, Malus sylvestris Miller; pear, Pyrus communis L.; almond, Prunus dulcis [Miller] D. Webb; olive, Olea europaea L.; and peach, Prunus persica [L.] Batsch) exhibited similar percentage survival of immatures in generation 1 (62.50–87.5%) and similar sex ratios of their progeny (59.48–76.22% female). The developmental times of the first generation from the egg to adult stage ranged from 6.21 to 6.66 d and the percentage survival of immatures of generation 2 ranged from 66.20 to 88.32%. Reproduction (total eggs per female) was greatest for E. tularensis fed apple pollen. Based on life-table analyses of these pollens, apple pollen was found to be the best diet for this predacious mite. Mites fed grass pollens (cultivated and wild annual ryegrass, Lolium multiflorum Lamarck; soft chess, Bromus mollis L. var ‘Blando’; California brome, Bromus carinatus Hook and Arnott; oat, Avena sativa L. var. ‘California red’; barley, Hordeum vulgare L. var ‘UC476’; rye, Secale cereale L. var ‘Merced’; meadow barley, Hordeum brachyantherum Nevskii; and red fescue, Festuca rubra L. var ‘Malate’) showed 63–97% survival of immatures in generation 1, but survivorship decreased to 44% or less in their progeny. Thus, these grasses did not individually support long-term survival of E. tularensis. The first generation survival (21%) and reproduction (0.5 eggs per female) of the predatory mites fed wheat (Triticum aestivum L.) pollen was significantly lower than all other treatments. This study provided fundamental information for mass rearing of E. tularensis and to enhance the orchard performance of E. tularensis as a predator of citrus pests.

Genome discrimination by in situ hybridization in Icelandic species of Elymus and Elytrigia (Poaceae: Triticeae).

Abstract: The genome constitution of Icelandic Elymus caninus, E. alaskanus, and Elytrigia repens was examined by fluorescence in situ hybridization using genomic DNA and selected cloned sequences as probes. Genomic in situ hybridization (GISH) of Hordeum brachyantherum ssp. californicum (diploid, H genome) probe confirmed the presence of an H genome in the two tetraploid Elymus species and identified its presence in the hexaploid Elytrigia repens. The H chromosomes were painted uniformly except for some chromosomes of Elytrigia repens which showed extended unlabelled pericentromeric and subterminal regions. A mixture of genomic DNA from H. marinum ssp. marinum (diploid,Xa genome) and H. murinum ssp. leporinum (tetraploid,Xu genome) did not hybridize to chromosomes of the Elymus species or Elytrigia repens, confirming that these genomes were different from the H genome. The St genomic probe from Pseudoroegneria spicata (diploid) did not discriminate between the genomes of the Elymus species, whereas it produced dis...