[VIPS] Ideotype question (fwd)

'Toby' H D Bradshaw toby at u.washington.edu
Wed Oct 11 15:58:21 EST 1995


Forwarded from Rongling Wu, University of Washington.

-Toby Bradshaw
toby at u.washington.edu

---------- Forwarded message ----------
Date: Wed, 4 Oct 1995 22:10:41 -0700 (PDT)
From: Rongling Wu <nfl at u.washington.edu>

This is an important question, but it is not easy to answer without 
ecophysiological work.  I think the ideotypes in open conditions should 
have strong branch capacity and a large leaf area index, whereas the 
selection of ideotypes for a plantation should be focused on foliage 
efficiency.  Foliage efficiency is defined as stemwood production per unit 
leaf area (Cannell et al. 1983, in Silvae Genetica 32: 195-202), which is 
related to many physiological processes, such as leaf orientation, leaf 
area duration, leaf photosynthesis, and water-use efficiency.  Genotypes 
with high foliage efficiency are expected to have less branch and leaf 
biomass.  Clearly, such genotypes are suited for being densely planted.  I 
found there is considerable genetic variation in foliage efficiency in our 
F2/B1 material (see my dissertation, Fig. 3.4 in p.73).  I would like to 
further estimate broad-sense heritability and identify QTL for this trait 
based on your linkage map.
	
I think the ideotypes selected from an open condition cannot be applied 
to dense plantations.  Such ideotypes could be due to their large leaf area 
(and therefore branches).  When they are planted at a small spacing, they 
could poorly perform since between-tree competitions largely limit the 
development of branches (see Nelson et al. 1981, in the Can. J. For. 
Res.).  

Rongling





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