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... It is difficult to quantify the mechanism(s) responsible for competition-induced yield loss using traditional experimental techniques. A technique using yield and ¹³C discrimination (ΔΔ) for wheat, a C₃ plant, has been developed to separate total yield loss (TYL) into yield loss due to N (YLNS) and water (YLWS) stresses. The objective of this research was to determine whether the ΔΔ approach could ...
... Natural variations of the 13C/12C ratio have been frequently used over the last three decades to trace C sources and fluxes between plants, microorganisms, and soil. Many of these studies have used the natural-13C-labelling approach, i.e. natural δ13C variation after C3–C4 vegetation changes. In this review, we focus on 13C fractionation in main processes at the interface between roots, microorgan ...
... On the basis of multi-proxy analysis on TOC, TN, C/N, organic δ¹³C and grain size, sediment record from Qinghai Lake provides evidences of stepwise-patterned climatic change since 16 ka BP. Results show that Qinghai Lake underwent six environmental stages. From 16.2 to 14.3 ka BP and from 4.0 to 2.1 ka BP, the organic δ¹³C value was controlled by the concentration of atmospheric CO₂. Relative high ...
C4 plants; color; grasses; organic matter; paleoclimatology; soil; stable isotopes; summer; temperature; Greenland; South Africa
Abstract:
... High-resolution stable isotope variations and growth structure analyses of the last three millennia of a 6600-year stalagmite record at Cold Air Cave, Makapansgat Valley, South Africa, are presented. Growth layers, which are measurable over the last 250 years, are shown to be annual. The correlation between the width of growth layers and precipitation is strongly positive. Changes inδ¹⁸O andδ¹³C a ...
... Plant species that fix CO₂ by the C₄ cycle have higher rates of CO₂ uptake than species using the C₃ photosynthetic carbon reduction cycle. Greater CO₂ fixation capacity has been associated with reduced photorespiration, specialized leaf anatomy, and biochemical pathways that differ in C₃ and C₄ plants. The higher photosynthesis rate of C₄ species also results in more dry matter production per uni ...
... Carbon and oxygen isotope values of bovid tooth enamel and pedogenic carbonates were used to reconstruct the paleoenvironments associated with Middle Pleistocene archeological and paleontological sites from the Kapthurin Formation, Kenya. Fossil teeth and pedogenic carbonates were collected from lacustrine and fluvial facies (K3 and K3’) of the Kapthurin Formation (~543–509ka). Twenty teeth from s ...
... Thermal-based germination models are widely used to predict germination rate and germination timing of plants. However, comparison of model parameters between large numbers of species is rare. In this study, seeds of 27 species including 12 C₄ and 15 C₃ species were germinated at a range of constant temperatures from 5 °C to 40 °C. We used a modified thermal time model to calculate germination par ...
Bouteloua gracilis; C3 plants; C4 plants; Pascopyrum smithii; ecosystems; gas exchange; hydroponics; leaf water potential; leaves; niches; photosynthesis; physiological response; roots; stomatal movement; temperature profiles; water stress; Colorado
Abstract:
... Agropyron smithii (a C₃ species) and Bouteloua gracilis (a C₄ species) occur in the same habitat of the shortgrass prairie ecosystem in northeastern Colorado. The hypothesis tested in this study was that the two species differ in their fundamental niches partly as a function of their different physiological responses to temperature and moisture gradients. Growth and gas exchange patterns were meas ...
C4 plants; Sesuvium; Trianthema; center of diversity; herbs; new combination; petioles; phylogeny; plant taxonomy; species identification; taxonomic revisions; Central America; Southern Africa
Abstract:
... Sesuvium and Cypselea are closely related succulent genera within the Sesuvioideae (Aizoaceae). Since Cypselea is nested in Sesuvium in molecular studies and both genera share traits separating them from other members of the subfamily, we propose to include Cypselea in Sesuvium. Sesuvium (incl. Cypselea) comprises 14 species and is distributed worldwide with centres of diversity in southern Africa ...
... Cheetahs Acinonyx jubatus are important predators of herbivores in African ecosystems, and several methods to determine their diet have been used in the past. We applied a novel method to quickly assess the diet of cheetahs with respect to grazing and browsing herbivores, i.e. we analysed the stable carbon isotope ratio (δ¹³CV‐PDB) of cheetah breath to separate individuals feeding predominantly on ...
... Not-from-concentrate (NFC) juice has better nutrition, flavor and higher price than reconstituted juice. Accordingly, NFC juice is prone to adulteration and is an ongoing industry problem that has not yet been resolved. Undeclared addition of water and sugar are the main forms of NFC juice adulteration. This paper investigates the carbon and oxygen stable isotope ratios (δ¹³C and δ¹⁸O values) of t ...
... There is great concern about the environmental impact and toxicity of palladium (Pd) because of its widespread use in automotive catalytic converters and other applications. Pd migrates and transforms in the environment and is absorbed by plant roots where it affects plant growth and eventually enters the food chain. Here we explored the effects of Pd on the physicochemical and biochemical charact ...
... A comparison of carbon metabolism in the constitutive crassulacean acid metabolism (CAM) plant Kalanchoe daigremontiana Hamet et Perr. and the C3-CAM intermediate Clusia minor L. was undertaken under controlled environmental conditions where plants experience gradual changes in light intensity, temperature and humidity at the start and end of the photoperiod. The magnitude of CAM activity was mani ...
... Yellow-green foliage cultivars of four vegetables grown outdoors, i.e., Chinese mustard (Brassica rapa), Chinese kale (Brassica oleracea var. alboglabra), sweet potato (Ipomoea batatas) and Chinese amaranth (Amaranthus tricolor), had lower chlorophyll (Chl) (a+b) (29â36% of green cultivars of the same species), total carotenoids (46â62%) and ascorbate (72â90%) contents per leaf area. Further ...
... Soil food webs influence organic matter mineralization and plant nutrient availability, but the potential for plants to capitalize on these processes by altering soil food webs has received little attention. We compared soil food webs beneath C₃- and C₄-grass plantings by measuring bacterial and fungal biomass and protozoan and nematode abundance repeatedly over 2 years. We tested published expect ...
... Global warming is one of the most serious challenges facing us today. It may be linked to the increase in atmospheric CO₂ and other greenhouse gases (GHGs), leading to a rise in sea level, notable shifts in ecosystems, and in the frequency and intensity of wild fires. There is a strong interest in stabilizing the atmospheric concentration of CO₂ and other GHGs by decreasing carbon emission and/or ...
... The theoretically characterized (DFT) C₄ cumulenic species Mn(C₅H₄R)(dmpe) {CCCC(SnPh₃)₂} was obtained by photolysis of the Cₛₚ₂–Sn bond in the vinylidene complex Mn(C₅H₄R)(dmpe)[CC(SnPh₃)–CCSnPh₃], which in turn was prepared by a thermal reaction from MnC₅H₄R(dmpe)(C₇H₈) and Ph₃Sn–C₄–SnPh₃. ...
C4 plants; Miscanthus; Panicum virgatum; acclimation; canopy; carbon dioxide enrichment; climate; climate change; computers; corn; ecophysiology; energy; energy crops; mathematical models; momentum; user interface; vegetation; Midwestern United States
Abstract:
... Ecophysiological models that vertically resolve vegetation canopy states are becoming a powerful tool for studying the exchange of mass, energy, and momentum between the land surface and the atmosphere. A mechanistic multilayer canopy–soil–root system model (MLCan) developed by Drewry et al. (2010a) has been used to capture the emergent vegetation responses to elevated atmospheric CO₂ for both C₃ ...
... Leaf diffusion conductance much increased when Xanthium strumarium (C(3)), Atriplex prostata (C(3)) and Flaveria pringlei (C(3)), F. sonorensis (C(3)/C(4)), F. floridana (C(3)/C(4)), and F. trinervia (C(4)) plants were grown under relatively high (28 kPa) ambient oxygen. This phenomenon, which increases sensitivity to water stress, could have adversely affected vegetation during the late Cretaceou ...
... The present study is one of only few to address the stable carbon isotope (δ¹³C) and concentration dynamics of DIC, DOC, and POC over an entire hydrologic year, using a dataset of high sampling resolution (4–11 samples retrieved per month). This research was performed in the catchment of the Schwabach River, a typical mid-latitude small headwater stream in Germany emplaced mainly in karstic bedroc ...