title: Life history and resource acquisition: Photosynthetic traits in selected accessions of three perennial cereal species compared with annual wheat and rye.
abstract: OBJECTIVE
  Few previous studies have considered how plant age affects photosynthetic physiology in herbaceous perennials or how photosynthetic capacity in annual cereals compares to perennial relatives. Newly developed perennial cereals offer novel systems for addressing these questions. Our study makes a novel contribution by considering how life history differences affect photosynthetic physiology.
  
  
  METHODS
  In two linked field studies, we evaluated effects of life history and plant age on photosynthetic rates (A), and related biochemical, morphological, and water-relations traits, comparing 1- and 2-yr-old cohorts of perennial wheat, intermediate wheatgrass, and perennial rye to close annual relatives (wheat and rye).
  
  
  RESULTS
  Photosynthetic rates (A) were 10-50% higher in perennial cereals compared to annuals. In wheatgrass, elevated A was associated with higher carboxylation (VC), triose phosphate utilization (TPU) and electron transport rates (J), and higher leaf soluble protein and chlorophyll. Younger wheatgrass plants maintained higher A, TPU, J, and VC than older plants did. Perennial wheat and rye differed from annual relatives in some but not all of these parameters. Differences in stomatal limitation were not involved, while differences in stomatal conductance (gs) became evident under drier conditions.
  
  
  CONCLUSIONS
  This study demonstrates that some perennial cereal species can maintain higher midseason A than their annual crop relatives. These changes are not fully explainable by increased access to soil water and may reflect trade-offs between allocation to reproduction and to resource acquisition. We also found evidence for age-related changes in photosynthetic physiology in a herbaceous perennial plant.
authors: Department of Plant, Soil and Microbial Science, Michigan State University, East Lansing, Michigan USA.
authors: Nikhil S
authors: NS
authors: Jaikumar
authors: Sieglinde S
authors: SS
authors: Snapp
authors: Thomas D
authors: TD
authors: Sharkey
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D017753:Ecosystem; D004579:Electron Transport; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis; D063245:Plant Development; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology; D012098:Reproduction; D012621:Seasons; D012434:Secale / Q000502:physiology*; D012987:Soil / Q000737:chemistry; D014908:Triticum / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D014867:Water / Q000502:physiology
chemical_list: D010940:Plant Proteins; D012987:Soil; D014867:Water; D002734:Chlorophyll; D002245:Carbon Dioxide; D009584:Nitrogen
keywords: Poaceae; Thinopyrum; Triticum; age; annual; perennial; photosynthesis; whole plant