Intraspecific carbon and nitrogen isotopic variability in foxtail millet (Setaria italica)

Abstract

The variation found is large enough to have archaeological implications and within- and between-plant isotope variability should be considered in isotope studies. The range in δ(15) N values is particularly significant as it is larger than the typical values quoted for a trophic level enrichment, and as such may lead to erroneous interpretations of the amount of animal protein in human or animal diets. It is therefore necessary to account for the variability in plant stable isotope values during palaeodietary reconstructions. Copyright © 2016 John Wiley & Sons, Ltd.

Carbon and nitrogen isotope variability in the seeds of two African millet species: Pennisetum glaucum and Eleusine coracana

“…Maize also exhibits a similar range in carbon isotope ratios (2.2‰) among varieties . As noted by Lightfoot et al, regardless of their cause, such large ranges among accessions have significant implications for archaeology. For example, oft‐cited explanations for high δ 15 N values in plant material (e.g., manuring or aridity) may not be necessary to explain even rather considerable differences in δ 15 N values.…”

“…Although geographical, environmental, and agricultural differences are certainly at play for the Harlan Collection specimens, given that we still see large isotopic ranges in plants grown together under the same field conditions (1.2‰ in δ 13 C values and 3.5‰ in δ 15 N values), genetic differences must also be playing a role. Lightfoot et al observed a 2‰ range in δ 13 C values and a 6‰ range in δ 15 N values in Setaria italica accessions and argued that these ranges were larger than expected given the within‐ and between‐leaf and panicle variations that they observed. As noted above, Hubick et al found that carbon isotope discrimination varied significantly among genotypes of sorghum ( Sorghum bicolor ), which they argued could be related to either transpiration efficiency or light use efficiency of carbon fixation at the leaf level.…”

“…The relationships between these various environmental factors and modern C 3 plant δ 13 C values have been relatively well studied (e.g.,), and some of that work has been in Africa, but there have been fewer publications focusing on environmental variation in C 4 plants. Those C 4 plants that have received attention regarding environmentally driven isotopic variation have tended to be archaeologically and economically important species, such as maize, sorghum, and, more recently, foxtail millet ( Setaria italica ) . The standard carbon isotope model for C 3 plants posits a negative correlation between plant δ 13 C values and water availability (e.g., precipitation, relative humidity) – that is, an increase in precipitation will increase stomatal conductance and in turn decrease plant δ 13 C values.…”

“…In Africa, pioneering isotopic research has provided intriguing insights into ancient food webs and cereal consumption . However, recent research in East Asia and other regions has demonstrated more variability in C 4 cereal (e.g., foxtail millet, Setaria italica ) isotopic signatures than previously assumed . This has significant implications for the interpretation of ancient diets based on stable isotope signatures globally.…”

Interpretation of bulk nitrogen and carbon isotopes in archaeological foodcrusts on potsherds

“…In particular, those in human bone collagen have been reported from a very wide range of time (from Late Pleistocene to modern) and space (from the Old to the New World) since the 1970s . In the last decade, this journal has contributed to the establishment of isotopic studies on charred plant remains, which significantly expanded the domain of knowledge concerning agriculture of the past . In this study, we focus on another possible source of isotopic information from the past, carbonized residue adhering to the surface of pottery, sometimes called foodcrust, which has been measured in order to estimate the materials cooked or processed in the vessels .…”