Limitation factors for photosynthesis in 'Bluecrop' highbush blueberry (Vaccinium corymbosum) leaves in response to moderate water stress
Journal
Journal of Plant Biology
Journal Volume
55
Journal Issue
6
Pages
450-457
Date Issued
2012
Author(s)
Abstract
The levels of stomatal, mesophyll and biochemical limitations in CO2 assimilation of 'Bluecrop' highbush blueberry leaves were compared at two different levels of leaf water potential. The leaf water potentials were -1.49 and -1.94 MPa in daily-irrigated (DI) and non-irrigated (NI) shrubs, respectively. The NI shrubs represented plants under moderate water stress. Mesophyll conductance (gm) and chloroplastic CO2 concentration (Cc) were estimated by combined measurements of gas exchange and chlorophyll fluorescence under various intercellular CO2 concentrations (Ci). Net CO2 assimilation rates (An) as a function of Cc were used for calculating maximum carboxylation efficiency (αcmax) at the real sites of CO2 assimilation. Maximum An (Anmax) from the light response curves at 400 μmol mol-1 air of ambient CO2 concentration (Ca) were lower in the leaves of NI shrubs than in those of DI ones. However, electron transport rates were higher in the leaves of NI shrubs than in those of DI ones. The decrease in CO2 assimilation following water stress may be caused by a decrease in gm rather than a decrease in stomatal conductance (gs) according to limitation analysis. Limitation rates by gs, calculated at 400 μmol mol-1 air of Ca in An-Ci curves, were not significantly different between the leaves of DI and NI shrubs. However, limitation rates by gm from An-Cc curves were significantly higher in the leaves of NI shrubs than in those of DI ones. Maximum carboxylation efficiency (αcmax) values calculated from the An-Cc curve, contrary to those calculated from the An-Ci curve, were higher in the leaves of NI shrubs than in those of DI ones. Consequently, mesophyll limitation than stomatal and biochemical limitations mainly down-regulated the photosynthesis in the leaves of 'Bluecrop' blueberry shrubs during moderate water stress. © 2012 Korean Society of Plant Biologists and Springer-Verlag Berlin Heidelberg.
Publisher
Springer Science and Business Media, LLC
Type
journal article