ISSN:
1365-3040
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Patchy stomatal movements were induced in leaves of Helianthus annuus L. and Xanthium strumarium L. by increasing Δw and decreasing light in a gas-exchange cuvette. The dynamics of the patchy movements were recorded and analysed using images of chlorophyll fluorescence, and the influence of heterogeneous stomatal activity on gas-exchange measurements of whole-leaf stomatal conductance was explored. Image series and gas-exchange measurements from two contrasting 100 min experiments are presented. One series of images, taken using Helianthus annuus, was characterized by strongly oscillating stomatal conductance induced by a decrease in light at high Δw. Fluorescence analysis revealed that individual patches of the leaf displayed a variety of behaviours (from static to strongly oscillating fluorescence), which, when averaged, matched the time dependence of the oscillating stomatal conductance measured by gas-exchange techniques. During the second series of images, taken using Xanthium strumarium, stomatal conductance (measured with gas exchange) declined slightly after an increase in Δw, and then maintained a steady state. Again, some patches in this leaf showed highly dynamic qNP, although on the whole qNP varied without any obvious pattern or frequency. When all patch activity in this series was averaged, it paralleled the steady whole-leaf stomatal conductance determined by gas-exchange measurements. It is clear from this work that coordinated patchy stomatal movements can contribute significantly to the dynamics of whole-leaf stomatal conductance, and, in contrast, that dynamic but uncoordinated patchy movements can average to produce a steady gas-exchange trace.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3040.1994.tb02033.x
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