Page 149 - FRUTAS DEL TRÓPICO

intRoduction to teRminology and techniques foR studying enviRonmental
physiology of subtRopical and tRopical fRuit cRops 149

Water-use efficiency (WUE), net CO assimilation divided by transpiration (A/E) provides a
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comparison of the amount of CO entering the leaf to the amount of H O leaving the leaf.
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Figura. 2. Effect of flooding on net CO assimilation (A) of Annona squamosa and Annona glabra.
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(From Ojeda et al., 2004).

10 'Gefner' on A. squamosa - flooded

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A (µmol CO 2 m -2 s -1 ) 6
'Gefner' on A. glabra - flooded

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0
0 5 10 15 20 25 30
Days after flooding imposed

Stomatal conductance for CO (gc) or H O (gs) is a measure of how much resistance
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there is to CO entering the leaf or H O exiting the leaf through the stomates, i.e., the more
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the stomates are closed, the lower the stomatal conductance. In the older literature, stomatal

conductance was reported as stomatal resistance which is the inverse of stomatal conductance

(i.e., 1/stomatal conductance). There is generally more resistance to water moving out of a

leaf than CO moving into a leaf. This provides the basis for anti-transpirants which allow CO
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into the leaf but create a barrier to prevent much H O from being transpired from the leaf.
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Universidad Autónoma de Chiapas