[VIPS] Ideotype question

'Toby' H D Bradshaw toby at u.washington.edu
Wed Oct 11 15:53:34 EST 1995


The Chen/Ceulemans models seek to maximize light interception at the
canopy level, if I'm reading the papers correctly.  Don Dickmann tells me
that, on a per-leaf basis, photosynthesis is light-saturated at levels
quite a bit below full sun.  I have a couple of questions: 

1) Is there a way for your models to maximize net photosynthesis at
	the canopy level, instead of light interception, by tailoring
	leaf orientation to capture only the amount of light necessary
	to saturate photosynthesis, and letting the rest through to
	the leaves lower in the crown?  I realize that this would
	take some tinkering since you'd be trying to optimize over
	days and seasons when the angle/intensity of the sun is
	also changing, but you seem to be able to do this for
	light interception already.

2) Would it make sense to even try to optimize photosynthesis
	rather than just light interception?

3) Don tells me that a generalized leaf ideotype would have
	more vertically-oriented leaves in the upper crown
	(to let "excess" light penetrate into the lower
	crown), but more horizontal leaves in the lower
	crown to capture increasingly attenuated light.
	In "real life" do you see variation of leaf orientation
	in different positions within the crown?  That is, can
	we expect to have genetic variation for differences
	in leaf orientation among crown positions?

-Toby Bradshaw
toby at u.washington.edu






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