Progress 02/01/99 to 01/31/05
Outputs
No progress during this reporting period.
Impacts
This research aims to identify ornamental plants that are tolerant of stresses associated with urban planting sites.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
The physiological basis of leaf scorch is being investigated for three Aesculus species: A. flava (yellow buckeye), A. pavia (red buckeye), and A. parviflora (bottlebrush buckeye). Small trees of each species were grown in pots, subjected to full sun or 80% shade and well-watered or subjected to drought. Leaf scorch was most prevalent in full sun, whether plants were well-watered or under drought stress. Stomatal conductance decreased during the growing season, and was lower under drought than in well-watered trees, but was little affected by shade. Drought stress also lowered the relative water content of leaves but osmotic potential of leaves after hydration was constant across all treatments, and did not change with time. In the absence of osmotic adjustment and stomatal regulation of water loss, desiccation and abscission of leaves could be an adaptive response to excessive evaporative demand.
Impacts
This research aims to identify ornamental plants that are tolerant of stresses associated with urban planting sites.
Publications
- Knee, M. Atiyeh, R.M., and Cavender, N.D. (2003) Vermicompost stimulates mycorrhizal colonization of roots of Sorghum bicolor at the expense of plant growth. Pedobiologia 47:85-89.
- Knee, M., Struve, D.K., Bridgewater, M.H. and Phillips, J.W. (2003) Growth and water use by four leguminous tree species in containers on a gravel surface or embedded in mulch. Ornamental Plants Ann. Rep & Res. Rev. 2002, Spec. Circ. 189, OARDC, Wooster, OH, pp 57-64.
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Progress 01/01/02 to 12/31/02
Outputs
Growth and water use were investigated for four leguminous tree species growing in containers on gravel or in a mulch bed. Root growth was inhibited in the containers on gravel, which were exposed to the sun, but top growth was only affected for the most vigorous species, Robinia pseudoacacia. The relationship between water usage and leaf area was similar to published observations for other tree species for R. pseudoacacia and Gleditsia triacanthos. However, Cercis Canadensis and Gymnocladus dioicus had lower water requirements. Eryngium yuccifolium is a handsome herbaceous perennial that is tolerant of drought and compacted soils, but it is difficult to propagate. At seed maturity its embryos have not reached a germinable size. Embryo development is promoted by cold stratification, but the seed coat contains phenolic germination inhibitors that can be removed from by extensive washing with water. Enhanced oxygen levels do not promote germination, but appear to reduce
seed viability.
Impacts
This research aims to identify ornamental plants that are tolerant of stresses associated with urban planting sites
Publications
- Knee, M. and Thomas, L. C. 2002. Light Utilization and Competition Between Echinacea Purpurea, Panicum Virgatum and Ratibida Pinnata Under Greenhouse and Field Conditions. Ecological Research. 17(5):591-599.
- Schutte, B.J. 2002. Embryo and pericarp contributions to seed dormancy of Eryngium yuccifolium Michx. (Apiaceae) and techniques for dormancy removal. M.S. Thesis, The Ohio State University.
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Progress 01/01/01 to 12/31/01
Outputs
Previous work indicated a relationship between growth of different plant species in compacted soils and radicle elongation of seedlings under high atmospheric pressure. A collection of tomato breeding lines was screened for response to soil compaction and radicle elongation under pressure. While there was variation in both characters there was no relationship between them, indicating that the response to pressure does not offer a rapid screen for resistance to soil compaction. Indoor plant environments are characterized by low light and humidity, but above-ambient carbon dioxide concentrations. Photosynthesis was measured in four ornamental foliage plants at different carbon dioxide and light levels. Two of the four species showed a short-term increase in quantum yield of photosynthesis with increasing carbon dioxide, however there was evidence of an adaptive down-regulation of photosynthesis after 30 days in 700 ppm carbon dioxide. A commercial mycorrhizal inoculum
did not promote growth of the prairie grass, big bluestem, in urban or agricultural soils. Growth promotion did occur in a low phosphorus soil and was higher with inoculum derived from an established prairie site. Water use by ornamental tree species is being investigated in relation to potential evapotranspiration.
Impacts
This research aims to identify ornamental plants that are tolerant of stresses associated with urban planting sites.
Publications
- CAVENDER, N.D. 2001 Genetic variation of big bluestem (Andropogon gerardii) and its association with arbuscular mycorrhizal fungi: Implications for prairie restoration and reintroduction. Ph.D. Dissertation, The Ohio State University.
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Progress 01/01/00 to 12/31/00
Outputs
Following research on the ability of roots of prairie grass and for species to grow under conditions of physical restriction, similar species have been planted on a compacted soil site with and without amendment to improve soil structure. Preliminary indications are that growth is not improved by the soil amendment. A number of Salix (willow) species were grown in a hydroponic system in the presence of cadmium, copper or animal waste leachate. The species were generally tolerant of high (0.025 mM) metal concentrations, although solution concentrations did not decrease. Metals appeared to be passively taken up with the transpiration stream. Similarly the plants did not cause a large decrease in the ammonium, nitrate or phosphate concentration in the animal waste. Genetic variation was studied in populations of Andropogon gerardii (big bluestem) from Ohio and states to the west using the RAPD procedure. None of the DNA fragments isolated was found to be unique to a
particular source. Ohio populations were most similar to populations from Indiana and Wisconsin, but remote from Kansas and Missouri.
Impacts
This research will identify plants that are tolerant of stresses associated with urban and industrial planting sites. It will also show the extent to which natural, ecotypic variation is important in selecting plants for such sites.
Publications
- Knee, M. 2000. Establishment of grass and wildflower mixes for low-maintenance landscapes. Ornamental Plants Annual Report Research Review Special Circular 173 Ohio Agric. Res. Dev. Center, Ohio State Univ. pp 79-82.
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Progress 01/01/99 to 12/31/99
Outputs
Competition between three ornamental species, endemic to the tall-grass prairie, was examined in replacement series experiments, both in the greenhouse and in the field. In both environments Echinacea purpurea was a poor competitor with Ratibida pinnata or Panicum virgatum. R. pinnata and P.virgatum seemed to be equally aggressive. P. virgatum and R. pinnata achieved higher maximum photosynthetic rates than E. purpurea, but E. Purpurea maintained relatively higher rates at low PPF than the other two species. E. purpurea in mixed plantings with the other two species experienced lower PPF than in monoculture. Under field conditions, E. purpurea had both a high transpiration rate and high leaf area ratio (LAR), whereas P. virgatum had low transpiration with high LAR and R. pinnata had high transpiration and low LAR. A number of mixes of native grasses and forbs were evaluated three years after sowing on a xeric and a mesic site. Mixes based on warm-season shortgrasses
such as Schizachyrium scoparium did not establish well on either site. Mixtures containing tallgrasses alone (Andropogon gerardii, Sorghastrum nutans and Panicum virgatum) established well on both sites. The presence of forbs in the mix prevented grass establishment on the xeric site, whereas grass and forbs established successfully on the mesic site. A greater proportion of the forb species in mixes became established on the mesic than on the xeric site. The only exceptions were Silphium species which were found on the xeric but not on the mesic site.
Impacts
Strategies for establishment of low maintenance landscapes will result from this research.
Publications
- Knee, M., Brake, R.A., Cavender, N.D., and Thomas, L.C. 1999 Growth of ornamental plants in compacted soils and media. Ornamental Plants Ann. Rep. Res. Rev., Spec. Circ. 165 Ohio Agric. Res. Dev. Center, Ohio State Univ. pp113-119.
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