• Environmental Factors Influencing Gardner Saltbush Seed Dormancy Alleviation

      Ansley, R. J.; Abernethy, R. H. (Society for Range Management, 1985-07-01)
      Pregermination treatments applied to seed of Gardner saltbush, [Atriplex gardneri (Moq.) D. Dietr.] were evaluated for alleviation of seed dormancy. Treatments selected simulated conditions the seed might be exposed to in its natural environment, including dry afterripening, scarification, leaching, and cold stratification. Germination response to individual treatments was equal to or higher than nontreated seed. Germination percentage of afterripened seed was increased from 17% for nontreated filled seed to an average of 86% of filled seed by the combined treatments of scarification, leaching, and 4-week stratification. This combination of treatments allowed optimum germination. Response to treatments provided evidence as to the type of dormancy in Gardner saltbush seeds. The levels of germination response to specific treatments appears to be an adaptation to ensure a temporal dispersal of dormancy release and seedling emergence. Pregermination treatments used in this study were relatively easy to apply to the seeds and stimulated germination without potentially damaging the embryo. Thus, they would be useful in revegetation by direct seeding efforts.
    • Evidence of cell deterioration in winterfat seeds during refrigerated storage

      Booth, D. T.; Agustrina, R.; Abernethy, R. H. (Society for Range Management, 1999-05-01)
      Effective storage of wildland seeds helps alleviate supply shortages and mitigates variable production associated with annual weather patterns. The storage environment is critical for seeds like winterfat [Eurotia lanata (Pursh) Moq.] that rapidly lose viability under ambient conditions. Defining seed response to storage conditions is basic to effective seed storage programs. We used electron micrographs of freshly collected, and of stored winterfat seeds, with vigor tests to compare seedling vigor and to relate seed performance to seed cell biology as influence by; (a) seed age under known storage conditions, and (b) imbibition temperatures. We found that imbibition temperatures had little influence on the vigor of fresh seeds but significantly influenced aged seeds. Mitochondrial deterioration was evident in winterfat seeds stored 5-6 years at 5 degrees C, and in fresh, but incompletely hydrated seeds held at 20 degrees C. We recommend seeds be held at -18 degrees C or colder for long-term storage and that field seedings be done during the cold season to reduce the chance that incompletely hydrated seeds will be exposed to warm temperatures.
    • Seed Pretreatments and Their Effects on Field Establishment of Spring-Seeded Gardner Saltbush

      Ansley, R. J.; Abernethy, R. H. (Society for Range Management, 1984-11-01)
      Gardner saltbush [Atriplex gardneri (Moq.) D. Dietr.] seeds collected from the Red Desert Basin of Wyoming were subjected to pretreatments of scarification (Sc), washing (W), and stratification (St) to alleviate dormancy. Laboratory germination was evaluated. Subsequently, seedling vigor was observed by determining field emergence of similarly pretreated seeds spring planted at 1 irrigated and 2 dryland sites in Wyoming. Effects of 1-cm and 3-cm planting depths on emergence were also evaluated. Seed was pretreated, then dehydrated with minimal impact on seed germination. Field emergence was much less than laboratory germination for all treatments at all sites, indicating that establishment for this species is related to poor seedling vigor as much as to seed dormancy. Moreover, when compared to untreated controls, relative responses to seed pretreatments often differed between laboratory and field trials. In the laboratory Sc = W = St provided the greatest germination, whereas the best seed pretreatment for field establishment was Sc + St. Washing had little effect on enhancing field emergence and appeared to inhibit effects of St in scarified seed. The most effective planting depth varied with climatic/edaphic severity of the site.
    • Seedling competition between mountain rye, 'Hycrest' crested wheatgrass, and downy brome

      Buman, R. A.; Monsen, S. B.; Abernethy, R. H. (Society for Range Management, 1988-01-01)
      For comparison of seedling growth competitive responses in a controlled environment, monocultures (intraspecific) and 2 species mixtures (interspecific) of mountain rye (Secale montanum), crested wheatgrass (Agropyron cristatum × desertorum 'Hycrest'), and downy brome (Bromus tectorum) were established. Seedling dry root and shoot weights, shoot area, and maximum root length were compared at 1, 2, 3, and 6 weeks of growth in shoot roots boxes under a growth chamber environment (16 hr @ 14 degres C, 1,000 micro-E m-2 sec-1; 8 hr @ 10 degrees C, dark). Soil moisture depletion was monitored gravimetrically. Dry root and shoot weight, shoot area, and root length of mountain rye was greater than that of both downy brome and Hycrest crested wheatgrass at every sampling period over the 6-week study when grown in two-species mixtures. No difference was obtained for these seedling growth characters between downy brome and Hycrest mixtures, except for a 6.4 cm vs. 4.8 cm maximum root length at 1 week of growth. Similarly, in monoculture, mountain rye generally produced greater seedling growth than the other 2 species, although exceptions occurred for root weight, shoot area, and root length by 6 weeks of growth. Mountain rye depleted soil moisture in the growth boxes more rapidly and to a lower potential than the other 2 species. The results of this study indicate mountain rye provide vigorous competition as a seedlling.
    • Temperature requirements for mountain rye, Hycrest crested wheatgrass, and downy brome germination

      Buman, R. A.; Abernethy, R. H. (Society for Range Management, 1988-01-01)
      In this study we determined that mountain rye (Secale montanum), crested wheatgrass (Agropyron cristatum × desertorum 'Hycrest'), and downy brome (Bromus tectorum) have similar germination temperature requirements and thus have the potential to germinate under similar soil temperature regimes, a feature which could be advantageous for subsequent seedling competition of mountain rye or crested wheatgrass against downy brome. Germination temperature profiles were compared using a thermogradient germination plate. Fifty-six different day/night temperature regimes were utilized for the comparisons. The bivariate spline model was found to be the best model for predicting germination-temperature response of the 3 species. Mountain rye and downy brome produced high germination under widely fluctuating (20-30 degrees C, 16 hr day/5-10 degrees C, 8 hr night) temperature regimes with crested wheatgrass demonstrating an optimum germination temperature over a 10-20 degrees C day/25 degrees C night regime. One of the 2 downy brome sources evaluated exhibited a much broader optimum germination temperature range. However, the differences in germination temperature profiles obtained were not of a magnitude likely to be biologically or ecologically significant due to the relatively high germination obtained over a wide range of fluctuating day/night temperatures for all 3 species.
    • Value of mountain rye for suppression of annual bromegrasses on semiarid mined lands

      Andersen, M. R.; Depuit, E. J.; Abernethy, R. H.; Kleinman, L. H. (Society for Range Management, 1992-07-01)
      The value of mountain rye (Secale montanum Guss.) for competitive suppression of 2 annual bromegrasses (downy brome, Bromus tectorum L. and Japanese brome, B. japonicus Thunb) was investigated in a 3-year study on reclaimed coal mined lands in southeastern Montana. Rye established rapidly and vigorously, but did not persist appreciably (either through initially established plants or new seedlings) after the second year. However, mountain rye significantly reduced growth and reproduction of annual bromes during the first 2 growing seasons. Mountain rye also inhibited growth of other concurrently seeded perennial grasses during the first 2 seasons. Annual brome soil seedbanks were not sufficiently reduced in rye-seeded plots to prevent an eventual, third year recovery of brome productivity after a massive dieback of rye between the second and third growing seasons. Mountain rye therefore proved effective for short but not for longer-term control of annual bromes. This study did not allow distinction between the known short-lived nature of mountain rye and/or local environment as causal factors for the massive dieback after the second year.