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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Photosynthesis And Water Relations Of Two Savanna Grasses As Influenced By Shade And Water Stress, M J. Trlica, J I. Kinyamario
Photosynthesis And Water Relations Of Two Savanna Grasses As Influenced By Shade And Water Stress, M J. Trlica, J I. Kinyamario
IGC Proceedings (1993-2023)
Net CO2 assimilation and plant water relations of the African savanna grasses Panicum maximum Jacq. and Tliemeda triandra Porrsk. were measured under controlled conditions. We hypothesised that 1; triandra would be better adapted to higher light and temperature conditions and could withstand greater moisture stress than could P. maximum, as T. tria11dra is commonly found in open areas, whereas P. maximum dominates in the shade of trees. Plants of both species were transplanted into a common soil in large pots and placed under shade (approximately 150 µrnoVm1/s photon flux density (PFD)) or high light (approximately 1200 µmoVm1/s PFD) conditions, with …
Climate Change And Grasslands: Ecosystem-Level Responses To Elevated Carbon Dioxide, Clenton E. Owensby
Climate Change And Grasslands: Ecosystem-Level Responses To Elevated Carbon Dioxide, Clenton E. Owensby
IGC Proceedings (1993-2023)
Elevated CO2 is the major greenhouse gas associated with global climate change. The impact of increasing atmospheric CO2 on grassland ecosystems has been studied little. Studies with single plants or populations in controlled environments have provided knowledge of the mechanisms involved in plant response to elevated CO21 but without ecosystem-level studies over an extended period, we will be unable to make any valid predictions. Primary production of grassland ecosystems under elevated CO2 will likely increase, with the greatest increase coming with C3-dominated plant communities, or plant communities that are .subjected to frequent drought stress. Increased nitrogen-use efficiency and reduced nitrogen …
Photosynthesis And Water Relations Of A C4 And A C3 Grass Under Doubled Carbon Dioxide, D Nie, M B. Kirkham, E T. Kanemasu
Photosynthesis And Water Relations Of A C4 And A C3 Grass Under Doubled Carbon Dioxide, D Nie, M B. Kirkham, E T. Kanemasu
IGC Proceedings (1993-2023)
The objective of this project was to determine during an entire season the photosynthetic rate and water potential of a C3 grass (Kentucky bluegrass, Poa pratensis L.) and a C4 grass (big bluestem, Andropogon gerardii Vitman) grown with 2 levels of CO2 (ambient or twice ambient) and 2 water levels (field capacity or no water added). Elevated CO2 increased the photosynthetic rate of Kentucky bluegrass by an average of 76%. During mid-season (11 June-16 July), photosynthetic rate of high-water big bluestem with ambient CO2 was about the same as that of low-water big bluestem with doubled CO2• Under both water …
Whole-Stand Carbon Gains And Nitrogen Distribution In Herbaceous Stands, M.J A. Werger, T Hirose
Whole-Stand Carbon Gains And Nitrogen Distribution In Herbaceous Stands, M.J A. Werger, T Hirose
IGC Proceedings (1993-2023)
We studied canopy structure and leaf nitrogen distribution in open and dense stands of tall dicot and monocot herbs and compared the results with simulated canopy performance under uniform and optimised leaf nitrogen distributions. Dense stands showed leaf nitrogen distributions that greatly differed from those of uniform distribution but did not completely match optimum distribution. In dense stands this led to strongly enhanced potential whole canopy carbon gains, while in open stands the leaf nitrogen distribution was not very important in this respect. Dense stands of monocots kept more leaf nitrogen in the lower parts of their canopies than is …
Effects Of Water Deficit On Osmotic Adjustment And Photosynthesis Of Miscanthus Spp. Collected From Different Rainfall Regions, J Weng
IGC Proceedings (1993-2023)
Four entries of Miscanthus spp., collected from different rainfall regions, were transplanted in pots. They were subjected to S drying cycles; each cycle lasted 6-7 days. Leaf photosynthesis (Pn) began to decline when leaf water potential (L) declined to •l.3 to -1.S MPa; the L values at SO% Pn (½Pn) were -1.6 to -2.6 MPa, The L (1hPn) values were lower in plants collected from northern Taiwan (highly frequent rainfall) than those collected from southern Taiwan (distinct wet and dry season). Further, the L (½Pn) value became lower in all the entries when drying cycle was advanced, with northern Taiwan …
Some Ecological Aspects Of Semi-Natural And Temporary Grasslands, N Gaborcik, L Ondrasek, J Cunderlik, J Tomaskin, T Kizek
Some Ecological Aspects Of Semi-Natural And Temporary Grasslands, N Gaborcik, L Ondrasek, J Cunderlik, J Tomaskin, T Kizek
IGC Proceedings (1993-2023)
Some ecological aspects were studied in semi-natural and temporary grasslands at different levels of fertilizer application. The research was carried out in the upland region of central Slovakia at the altitude of 460 m in Banská Bystrica. At zero fertilizer application, soil CO2 production and Cox content were higher in the temporary grassland. Atmospheric N fixation was also higher in the temporary grassland. However, root accumulation, microbial biomass content and R : S ratio were lower in the temporary grassland. By comparison with the semi-natural grassland, leaf area index (LAI), net assimilation rate (NAR) and crop growth rate (CGR) were …
Growth And Physiology Respond Differently To Elevated Co2 In Nad-Me And Nadp-Me C4 Grasses, D R. Lecain, J A. Morgan
Growth And Physiology Respond Differently To Elevated Co2 In Nad-Me And Nadp-Me C4 Grasses, D R. Lecain, J A. Morgan
IGC Proceedings (1993-2023)
Plants with C4 photosynthesis have one of three decarboxylation enzymes in their bundle sheath cells. Reports suggest that bundle sheath leakiness to CO2 is highest in the NAD-ME group, lowest in the NADP-ME group and intermediate in the PCK group. We investigated the hypothesis that growth and photosynthesis of three NADME grasses would respond more to elevated CO2 than three NADPME grasses. Contrary to our hypothesis, growth of NADP-ME grasses was greater under elevated CO2, while none of the NADME grasses had a significant response. Increased leaf non-structural carbohydrates were associated with greater growth responses of NADP-ME grasses, while none …
Morphological And Physiological Response Of Planeleaf Willow (Salix Planifolia Pursh.) To Simulated Browsing, L Xu, J L. Dodd, M A. Smith, Q D. Skinner, W A. Laycock
Morphological And Physiological Response Of Planeleaf Willow (Salix Planifolia Pursh.) To Simulated Browsing, L Xu, J L. Dodd, M A. Smith, Q D. Skinner, W A. Laycock
IGC Proceedings (1993-2023)
Morphological and physiological responses of planeleaf willow (Salix planefolia Pursh.) to simulated browsing were studied under controlled conditions. The treatments consisted of every combination of three clipping intensities (30%, 60% and 90% of current twigs length removal) and three clipping timings (late winter, early spring and mid-summer). Increased clipping intensity stimulated bud activation; increased total leaf area and leaf size and increased the length of current year’s twigs. Mid-summer browsing increased the total number of leaves, the number of current twigs and decreased the length of current twigs. Higher browsing intensity resulted in higher photosynthetic rate of recently matured …
Nitrogen Fixation At The Mid-Atlantic Bight Shelfbreak And Transport Of Newly Fixed Nitrogen To The Slope Sea, C. R. Selden, M. R. Mulholland, K. E. Crider, S. Clayton, A. Macías-Tapia, P. Bernhardt, D. J. Mcgillicuddy Jr., W. G. Zhang, P. D. Chappell
Nitrogen Fixation At The Mid-Atlantic Bight Shelfbreak And Transport Of Newly Fixed Nitrogen To The Slope Sea, C. R. Selden, M. R. Mulholland, K. E. Crider, S. Clayton, A. Macías-Tapia, P. Bernhardt, D. J. Mcgillicuddy Jr., W. G. Zhang, P. D. Chappell
OES Faculty Publications
Continental shelves contribute a large fraction of the ocean's new nitrogen (N) via N2 fixation; yet, we know little about how physical processes at the ocean's margins shape diazotroph biogeography and activity. Here, we test the hypothesis that frontal mixing favors N2 fixation at the Mid-Atlantic Bight shelfbreak. Using the 15N2 bubble release method, we measured N2 fixation rates on repeat cross-frontal transects in July 2019. N2 fixation rates in shelf waters (median = 5.42 nmol N L−1 d−1) were higher than offshore (2.48 nmol N L−1 d−1) …