Limitations to photosynthesis at different temperatures in the leaves of Citrus limon

Carlos Pimentel, Cari Bernacchi, Steve Long

Research output: Contribution to journalArticlepeer-review

Abstract

The response of CO2 assimilation rate (A) to the intercellular partial pressure of CO2 (Ci) was measured on intact lemon leaves over a range of temperatures (10 to 40°C). The A/Ci response shows how change in the leaf temperature alters the activity of ribulose-1,5-bisphosphate (RuBP) carboxylase-oxygenase (Rubisco) and RuBP regeneration via electron transport. The rate of A reached a maximum of 7.9 to 8.9 μmol m-2 s-1 between 25 and 30°C, while dark respiration (Rd) increased with temperature from 0.4 μmol m -2 s-1 at 10°C to 1.4 μmol m-2 s -1 at 40°C. The maximum rates of carboxylation (V c,max) and the maximum rates of electron transport (Jmax) both increased over this temperature range from 7.5 to 142 μmol m -2 s-1 and from 23.5 to 152 μmol m-2 s -1, respectively. These temperature responses showed that A can be limited by either process depending on the leaf temperature, when Ci or stomatal conductance are not limiting. The decrease in A associated with higher temperatures is in part a response to the greater increase in the rate of oxygenation of RuBP compared with carboxylation and Rd at higher temperatures. Although A can in theory be limited at higher Ci by the rate of triose-phosphate utilization, this limitation was not evident in lemon leaves.

Original languageEnglish (US)
Pages (from-to)141-147
Number of pages7
JournalBrazilian Journal of Plant Physiology
Volume19
Issue number2
DOIs
StatePublished - Apr 2007

Keywords

  • A/C curves
  • Gas exchange
  • Lemon

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

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