Leaf chlorophyll, net gas exchange and chloroplast ultrastructure in citrus leaves of different nitrogen status

Tree Physiol. 2003 Jun;23(8):553-9. doi: 10.1093/treephys/23.8.553.


One-year-old 'Cleopatra mandarin' (Citrus reticulata Blanco) seedlings were raised in a greenhouse and fertilized with nitrogen (N) at four application frequencies. Nitrogen-deficient leaves (86 mmol N m-2) had less chlorophyll per unit area, but a greater chlorophyll a:b ratio than N-fertilized leaves (> 187 mmol N m-2). Leaf dry mass per area (DM area-1) and total chlorophyll concentration increased linearly with increasing leaf N, whereas chlorophyll a:b ratio declined. Net assimilation of CO2 (A(CO2)) and leaf water-use efficiency (WUE) reached maximum values in leaves with approximately 187 mmol N m-2. Nitrogen-deficient leaves exhibited small chloroplasts with no starch granules; grana and stroma lamellae that coincided with the accretion of numerous large plastoglobuli in the stroma disintegrated. High-N leaves had large chloroplasts with well-developed grana, stroma lamellae and starch granules that enlarged with increasing N concentration. The lack of an increase in A(CO2) capacity at leaf N concentrations above 187 mmol N m-2 appeared to be correlated with the presence of numerous large starch granules.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon Dioxide / metabolism
  • Chlorophyll / analysis
  • Chlorophyll / physiology*
  • Chloroplasts / physiology*
  • Chloroplasts / ultrastructure
  • Citrus / physiology*
  • Nitrogen / deficiency
  • Nitrogen / physiology
  • Plant Leaves / chemistry
  • Plant Leaves / physiology*


  • Chlorophyll
  • Carbon Dioxide
  • Nitrogen