super-optimal stomatal conductance

MEK104 at psuvm.psu.edu MEK104 at psuvm.psu.edu
Mon Nov 16 12:25:39 EST 1992


ajt at uk.ac.sari.rri (Tony Travis) wrote:

>I agree with you about 'sacrificing' water for mineral uptake - we tend to
>dwell on water use efficiency as if water is *allways* in short supply.
>One thing people tend to forget about is winter drought though (when the
>available water is frozen).

>It isn't in short supply here, today, in Scotland ;-)

I for one certainly don't tend to consider the effect of winter drought,
mostly because I usually work with deciduous species.  But I have done some
Douglas-fir water relations work, a species which is known to transpire
during winter, at least on the West Coast of the US.  I don't know if thats
the case with conifers here in the east, or in the inter-mountain region.
You're suggesting, perhaps, that 'self stressing' may be a means of drought
hardening?

Its been suggested that low leaf water content or potential does not always
indicate a 'stress', but may simply reflect high photosynthetic rate (via
open stomata).  The argument is that stomata would close if the leaf were
stressed.


Mark Kubiske                < MEK104 at PSUVM.PSU.EDU >
School of Forest Resources
Penn State University



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