Vol. 85 No: 2

Title:
Differential heat-induced changes in the CO₂ assimilation rate and electron transport in tomato (Lycopersicon esculentum Mill.)

Authors:
D. CAMEJO, E. NICOLÁS, W. TORRES and J.J. ALARCÓN

pp: 137-143

Abstract:
Measurements of leaf stomatal conductance, leaf CO₂ assimilation rate, leaf chlorophyll fluorescence, and a previously published biochemical model have been used to evaluate the thermo-tolerance of the photosynthetic apparatus in two tomato genotypes (‘Amalia’ and ‘Nagcarlang’). The study was carried out as two experiments. In Experiment 1, a brief (20 min) increase in leaf temperature to 35ºC reduced the photosynthetic rate of ‘Amalia’ leaves grown at 25ºC, but stimulated photosynthesis in ‘Nagcarlang’, due to an increase in the maximum rate of carboxylation of ribulose-1,5- bisphosphate-carboxylase/oxygenase (VCmax). The heat-sensitive step in ‘Amalia’ seemed to be the maximum rate of electron transport (Jmax). However, in Experiment 2, there was no significant difference between Jmax at 25ºC and 35ºC when plants had been acclimatised to these temperatures.

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