Carbon stable isotope (delta(13)C) analysis can be used to infer the origin and to estimate the flow of nutrient resources through animals and across ecological compartments. These applications require knowledge of the rates at which carbon is incorporated into animal tissues and diet-to-tissue discrimination factors (Delta(13)C). Studies of carbon dynamics in terrestrial vertebrates to date ha...

The responses of gas exchange and water use efficiency to nitrogen nutrition for winter wheat were investigated under well-watered and drought conditions. The photosynthetic gas exchange parameters of winter wheat are remarkably improved by water and nitrogen nutrition and the regulative capability of nitrogen nutrition is influenced by water status. The effects of nitrogen nutrition on photosy...

A strong correlation was previously observed between carbon isotope discrimination (Delta(13)C) of phloem sap sugars and phloem sap sugar concentration in the phloem-bleeding tree Eucalyptus globulus Labill. (J. Pate, E. Shedley, D. Arthur, M. Adams [1998] Oecologia 117: 312-322). We hypothesized that correspondence between these two parameters results from covarying responses to plant water po...

Mesophyll conductance to CO(2) (g(m)) limits carbon assimilation and influences carbon isotope discrimination (Delta) under most environmental conditions. Current work is elucidating the environmental regulation of g(m), but the influence of g(m) on model predictions of Delta remains poorly understood. In this study, field measurements of Delta and g(m) were obtained using a tunable diode laser...

It is well known that whole-plant water-use efficiency (transpiration efficiency of carbon gain, TE(C)) varies among plant species with different photosynthetic pathways. However, less is known of such variation among tree species within the C(3) group. Here we measured the TE(C) of seven C(3) tropical tree species. Isotopic analyses (delta(13)C, delta(18)O, and delta(15)N) and elemental analys...

Stable isotope composition of human tissue reflects that of foods consumed, and can provide information about diet independent of artifactual remains. Here we refine and test this method by analyzing nitrogen (delta(15)N) and carbon (delta(13)C) isotope ratios in historic North American Plains Indians hair. Gas-source isotope-ratio mass spectrometry provides high-precision data for both delta(1...

Many environmental factors affect carbon isotope discrimination in plants, yet the predominant factor influencing this process is generally assumed to be the key growth-limiting factor. However, to our knowledge this hypothesis has not been confirmed. We therefore determined the carbon isotope composition (δ(13)C) of plants growing in two cold and humid mountain regions where temperature is con...

a factorial pot experiment based on randomized complete blocks design with fourreplications was carried out in order to evaluate salt tolerance of four sugar beet cultivarsincluding madison (british origin) and three iranian cultivars (7233-p12, 7233-p21 and7233-p29) using carbon isotope discrimination (δ). plants were grown in sand culturemedium in greenhouse conditions. sugar beet cultivars w...

The end-Permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope (delta(13)C) composition of carbonate minerals. Several extinction scenarios consistent with these observations have been put forward. Secular variation in the calcium isotope (delta(44/40)Ca) composition of marine sediments provides a tool for ...

Leaf internal, or mesophyll, conductance to CO(2) (g(m)) is a significant and variable limitation of photosynthesis that also affects leaf transpiration efficiency (TE). Genotypic variation in g(m) and the effect of g(m) on TE were assessed in six barley genotypes (four Hordeum vulgare and two H. bulbosum). Significant variation in g(m) was found between genotypes, and was correlated with photo...