title: Mineral nutrient stoichiometric variability in Hedera helix (Araliaceae) seeds.
abstract: OBJECTIVE
  The analysis of variability in mineral allocation to seeds has rarely been considered in relation to allometric patterns and deviations from the allometric trajectory. Here, I examine the scaling of carbon (C), nitrogen (N), phosphorus (P) and sulfur (S) with seed mass in field-collected seeds of Hedera helix, taking into account that brood size might influence the allocation patterns.
  
  
  METHODS
  C, N and S contents of 56 individual seeds of different sizes were analysed by combustion using a standard automated CNHS procedure. P content was determined for 200 individual seeds using spectrophotometry after acid digestion of ashed samples. This sample included seeds from different brood sizes.
  
  
  RESULTS
  C and N content both varied isometrically with seed mass and this variable explained most of the variation in their content in seeds. P and S, however, varied allometrically with seed mass. Additionally, seed mass only explained 37·3 % and 37·6 % of the total variance in P and S content, respectively. Seeds with higher mass contained proportionately more P and, furthermore, the seeds from small broods contained proportionally more P than those from large broods.
  
  
  CONCLUSIONS
  Although seed mass in this species can be used as a surrogate of investment in C and N, it does not account for variability in allocation of nutrients such as P and S. The fact that larger seeds increased their P concentration when found in smaller broods might be a consequence of intense competition for this nutrient among developing seeds. Then, brood size may influence the mineral nutrient concentration of seeds.
authors.affiliation: Research Unit of Biodiversity, University of Oviedo, Spain. jrobeso@uniovi.es
authors.forename: José Ramón
authors.initials: JR
authors.lastname: Obeso
mesh_terms: D002244:Carbon / Q000032:analysis; D035981:Hedera / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D012639:Seeds / Q000737:chemistry* / Q000254:growth & development*; D013030:Spain; D013455:Sulfur / Q000032:analysis
chemical_list: D010758:Phosphorus; D013455:Sulfur; D002244:Carbon; D009584:Nitrogen