Hydraulic Redistribution in Slender Wheatgrass (Elymus trachycaulus Link Malte) and Yellow Sweet Clover (Melilotus officinalis L.): Potential Benefits for Land Reclamation

Hydraulic redistribution (HR) by plant roots can increase moisture content in the dry, mostly upper, parts of the soil. HR helps maintain the viability of fine roots, root hydraulic conductivity, microbial activity and facilitate nutrient uptake. Plants can supply water to other surrounding plants by HR under drought conditions. In oil sands reclamation areas in Northeastern Alberta, Canada, reconstructed soils commonly suffer from the problems of drought, high pH, salinity, and compaction, which often impact revegetation success. In this study, we investigated the HR potential of two herbaceous plants that are frequently present in oil sands reclamation sites: slender wheatgrass (Elymus trachycaulus Link Malte) and yellow sweet clover (Melilotus officinalis L.), using a vertically split-root growth setup and treatments with deuterium-enriched water. Our objective was to test the potential benefits of HR on drought responses of seedlings of the commonly used plant species for oil sand reclamation, balsam poplar (Populus balsamifera L.), when these plants were grown together under controlled environment conditions. We found that both wheatgrass and yellow sweet clover could redistribute water in the upward and downward directions. However, the amount of water released by the roots was not sufficient to alleviate the effects of drought stress on the associated balsam poplar seedlings. Longer-term field studies should be carried out in order to examine, under different environmental conditions, the potential benefits of HR in these herbaceous plants to the establishment and growth of other plant species that are used for land reclamation.

Predicting seed germination of slender wheatgrass [Elymus trachycaulus (Link) Gould subsp. trachycaulus] using thermal and hydro time models

Schellenberg, M. P., Biligetu, B. and Wei, Y. 2013. Predicting seed germination of slender wheatgrass [Elymus trachycaulus (Link) Gould subsp. trachycaulus] using thermal and hydro time models. Can. J. Plant Sci. 93: 793–798. Slender wheatgrass [Elymus trachycaulus (Link) Gould subsp. trachycaulus] is a native caespitose grass used for forage production and reclamation. The objective of this study was to quantify seed germination requirements of slender wheatgrass using thermal and hydro time models. Slender wheatgrass, San Luis, had a base temperature (Tb) of 9.48°C, and required 946.8°C h to reach 50% of seed germination. Seed germination of San Lius occurred at a temperature range of 10–30°C, with the highest germination rate being achieved at 20°C, and the highest final germination percentage being achieved at 25°C. At 20 and 25°C, San Luis had a hydro time constant of 61 MPa h, and a median base water potential of approximately 1.0 MPa, but the germination had low uniformity in reduced water potentials. Final germination was reduced at or lower than –0.6 MPa. Compared with many other cool-season native grasses of Northern Great Plains, a relatively warm temperature would be necessary for uniform seedling establishment of this grass. In reclamation seeding, the seedling emergence could reach the highest level at a temperature of 25°C.

Barley yield and nutrient uptake in rotation after perennial forages in the semiarid prairie region of Saskatchewan

Jefferson, P. G., Selles, F., Zentner, R. P., Lemke, R. and Muri, R. B. 2013. Barley yield and nutrient uptake in rotation after perennial forages in the semiarid prairie region of Saskatchewan. Can. J. Plant Sci. 93: 809–816. Alfalfa (Medicago sativa L.) is the most common perennial forage legume grown for hay and pasture in the semiarid Brown soil zone of the Canadian prairies. Perennial forages often are not recommended for inclusion in annual crop rotations due to lower grain yields and drier soils following forage stand termination, but this is based on research results from 50 yr ago. Three replicated experiments consisting of three grasses [slender wheatgrass (Elymus tracycaulus), intermediate wheatgrass (Elytrigia intermedia), and Dahurian wildrye (Elymus dahuricus)] grown in monoculture and in mixture with two alfalfa varieties (cv. Beaver or cv. Nitro) were terminated and seeded to barley (Hordeum vulgare ‘Harrington’) for 2 consecutive crop years at Swift Current, Saskatchewan. Soil water content was lower after the alfalfa–grass mixtures compared with the grass monocultures, even during a wet growing season. Barley yield and N concentration in the grain were significantly greater following Beaver alfalfa/grass mixture compared with grass monoculture in 3 and 4 of 6 site years, respectively. N uptake by the barley crop (grain and straw) was also significantly greater following Beaver alfalfa/grass mixture than following grass monoculture in all 6 yr. Both barley grain yield and N uptake after intermediate wheatgrass (grown in monoculture) were lower than after Dahurian wildrye or slender wheatgrass in 3 of 6 yr. The use of alfalfa and a short-lived grass species in hay and pasture mixtures in the Brown soil zone when grown in rotation with annual crops may indeed result in lower grain yields in the short term than continuous annual cropping systems, but the inclusion of alfalfa will provide a N benefit to the subsequent grain crop thereby enhancing yield and possibly its market value.

Species dynamic, forage yield, and nutritive value of seeded native plant mixtures following grazing

Schellenberg, M. P, Biligetu, B. and Iwaasa, A. D. 2012. Species dynamic, forage yield, and nutritive value of seeded native plant mixtures following grazing. Can. J. Plant Sci. 92: 699–706. There is increasing interest in native plants of North America for rangeland reseeding in the semiarid regions of western Canada. However, there is limited information available on forage yield, nutritive value and response to grazing of seeded native plant mixture. The objective of this study was to compare foliar cover, forage yield, and nutritive value of two different native plant mixtures under grazing. In 2001–2004, a study was initiated on Orthic Brown Chernozemic (Aridic Haploboroll) soil near Swift Current (lat. 50°25'N, long. 107°44'W), Canada. The experimental design was a randomized complete block with a full factorial arrangement of seed mixtures (7 species and 14 species) and stocking rates (1.3 and 2.7 animal units ha−1) with four replications of each treatment combination. The 7-species mixture produced more forage than the 14-species mixture in July, August, and September of all study years. The 7-species mixture, however, had lower crude protein than the 14-species mixture in August and September in 2002 and 2003. Neutral detergent fiber and acid detergent fiber concentrations were generally similar between the two mixtures for July, August, and September sampling for all 3 yr. Foliar cover of awned wheatgrass [(Elymus trachycaulus (Link) Gould & Shin. ssp subsecundus (Link) A. & D. Love.] and slender wheatgrass [Elymus trachycaulus (Link) Gould subsp. trachycaulus] was higher in the 7-species mixture than the 14-species mixture, but foliar cover of other species was similar between the two mixtures. Shrub species were rarely observed in the stand at any year. Higher stocking rate decreased foliar cover of slender wheatgrass and weeds, but foliar cover of other species was similar between the two stocking rates. Based on the results, a seed mixture of native cool-season grasses may be more productive than a combination of native warm- and cool-season grasses under semiarid region of western Canada, but inclusion of warm-season grasses could improve nutritive value by increasing protein content in the late summer months.

Bacterial endophyte communities of two wheatgrass varieties following propagation in different growing media

Bacterial endophyte communities of two wheatgrass varieties currently being used in the revegetation of military training ranges were studied. Culturable and direct 16S rDNA PCR amplification techniques were used to describe bacterial communities present in Siberian and slender wheatgrass seeds, leaf tissues, and root tissues following propagation in either sand or a peat-based growing mix. Our hypothesis was that the resulting plant endophytic communities would be distinct, showing not only the presence of endophytes originating from the seed but also the characteristics of growth in the two different growing media. Both culture and culture-independent assays showed the likely translocation of Actinobacteria, Firmicutes, and Gammaproteobacteria from seed to mature plant tissues as well as subsequent colonization by exogenous organisms. Statistical analysis of 16S terminal restriction fragment profiles identified growing media as having a greater significant effect on the formation of the endpoint endophytic communities than either plant tissue or wheatgrass variety. In silico digests of the ribosomal database produced putative identifications indicating an increase in overall species diversity and increased relative abundances of Firmicutes and Cyanobacteria following propagation in sand and Betaproteobacteria following propagation in the peat-based growing mix. Results indicated a substantial translocation of endophytes from seed to mature plant tissues for both growing media and that growing medium was a dominant determinant of the final taxonomy of the endpoint plant endophytic communities.

Slender Wheatgrass is Susceptible to Smut Caused by Ustilago phrygica from Turkey

Slender wheatgrass (Elymus trachycaulus (Link) Gould ex Shinners subsp. trachycaulus), family Poaceae, tribe Triticeae, is a native North American grass that is used as a livestock forage. Ustilago phrygica, a systemic ovary-smut fungus, is native to Turkey and West Asia and is pathogenic on Aegilops spp. and Taeniatherum caput-medusae (L.) Nevski subsp. asperum (Simonk.) Melderis (medusahead), an invasive weed in the western United States that is targeted for biological control. An isolate of the fungus (U.S. National Fungus Collections, BPI 871725; GenBank Accession No. DQ139961) was collected from medusahead in Turkey and screened for possible use in classical biological control of this weed. Screening was done in quarantine in a BSL-3 facility of the Foreign Disease-Weed Science Research Unit, USDA, ARS, Ft. Detrick, MD. The focus of screening was determination of host range of the fungus among related native and agriculturally important grasses in North America. A procedure was developed to consistently and quickly produce disease on medusahead and other grasses. Without vernalization, plants inoculated with U. phrygica will not produce smutted spikes (seedheads). Teliospores of the fungus were vacuum inoculated (1) onto caryopses (seeds) of medusahead and slender wheatgrass, which were then placed on moist germination paper in a petri dish or on moist vermiculite in plastic boxes. The dishes, sealed with Parafilm, and the boxes, covered with lids, were placed in a dark refrigerator at 3°C. After 8 weeks, all seedlings were transplanted into pots on a greenhouse bench at 22 to 25°C and 14 h light (photosynthetic photon flux density [PPFD] 620 μmol·s−1·m−2). The plants began to flower and produce smutted spikes 40 days later. These tests were repeated once. Fourteen of sixty medusahead plants from inoculated caryopses incubated on germination paper and nine of twenty-four plants from caryopses incubated on vermiculite became smutted and produced numerous smutted spikes per plant. Partial systemic infection was the norm, and all diseased plants had some spikes that were not diseased. One slender wheatgrass plant of nine plants grown from inoculated caryopses incubated on germination paper was also smutted and produced three diseased spikes. Nielsen (2) indicated susceptibility of slender wheatgrass to U. phrygica, but only as a single entry in a table under the synonym Agropyron trachycaulum (Link) Malte ex H. F. Lewis in a report on susceptibility of Aegilops spp. to U. phrygica. Because this is an obscure mention of the susceptibility of slender wheatgrass to U. phrygica, the fungus-host association does not explicitly appear in literature and is absent from relevant databases. Our tests with the fungus confirm that slender wheatgrass is susceptible to U. phrygica and lead us to conclude that the fungus would not be a good candidate for classical biological control of medusahead in North America. This formal report should establish this fungus-host association in literature and ensure reference in plant disease databases. References: (1) C. C. Allison. Univ. Minn. Agric. Exp. Stn. Tech. Bull. August:1, 1936. (2) J. Nielsen. Can. J. Bot. 70:581, 1992.

Performance of short-lived perennial grasses grown with and without alfalfa at a semiarid location in southern Saskatchewan

Tyically, crop rotations in the semiarid region of the Canadian prairies do not include perennial forages because forage termination produces negative effects on subsequent annual crops. Three short-lived perennial grass species, Dahurian wildrye grass (Elymus dahuricus Turcz. Ex Griseb), intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and slender wheatgrass (Elymus trachycaulus (Link) Gould ex Shinners), were compared for their forage productivity and persistence as short duration (3 yr) forage stands, either in a mixture with alfalfa (Medicago sativa L.) or in monoculture, in three trials at Swift Current, Saskatchewan. Intermediate wheatgrass produced 29 and 22% more forage and was more persistent than Dahurian wildrye or slender wheatgrass, respectively. In alfalfa mixtures, however, the grasses produced similar forage yield in two of three trials. Intermediate wheatgrass was more persistent in mixtures but yield compensation by alfalfa grown with Dahurian wildrye and slender wheatgrass produced similar total forage yield as these grass stands thinned during the third year of each trial. Intermediate wheatgrass and alfalfa mixtures could be utilized for short rotation forage stands in high-input crop sequences where stand termination is achieved with herbicides. Dahurian wildrye and alfalfa mixture has the best potential for short-rotation forages in organic crop systems of this region because it would require less tillage to terminate the stand. Key words: Crop rotation, forage yield