Tony and Albert
I have looked at this a long time ago (1991) and I got this from my
writings at the time:

Format: Stage (Zadoks 1974 scale,  Ceres wheat 1986 stage)

Start of germination (1,1)
Start of leaf primordia initiation, start of tillering, emergence
(10,1)
During the transition from leaf primordia initiation (tillering) to
spikelet iniation (jointing or elongation), Zadoks changes from 29 to 30
and Ceres stage becomes 2
End of spikelet differentation, flag leaf maturity, start of heading
(appearance of ear) (39,3)
Start and end of anthesis (60-69, 4-5)
Grain filling (70-89, 5-6)
Maturity (90)
Ready for harvest (94)

I hope this all still applies and that it helps.
Abraham Singels


>>> [log in to unmask] 06 March 2002 04:36:39 >>>
Albert .... you hit on a really 'fuzzy' problem! The Zadoks conversion
is based
on developmental (ie. reproductive) progress throughout whereas Zadoks
itself
is a growth+development scale ... in the early stages there is no way
to relate
developmental progress to things like tillering (especially beginning
of
tillering), and later the associations can only be made 'fuzzily'. In
fact, the
only really hard point of contact is at last leaf (Zadoks 29,Istage 3
just
reached) ... and possibly also, physiological maturity (although this
is not
nailed down as such in Zadoks). I've been trying to develop a somewhat
better
conversion, and attach my current attempts for your perusal and
comments.
       As to the critical N curves. They also are 'fuzzy' .. even
without the
Zadoks problem, and really need some simplification ... and perhaps
linking to
something that accounts for current leaf sizes (big leaves have more
structural
material!), and leaf to stem ratio.
       Hope this is of some use .... Tony Hunt

Albert Weiss wrote:

> Colleagues: In the subroutine NFACTO of CERES-Wheat, there is an
algorithm
> for the calculation of a modified Zadoks scale (ZSTAGE) based on the
1-5
> development scale (XSTAGE) used in CERES Wheat. (By modified, I mean
that
> values are calculated in 0-9 range rather than in the 0-99 range, as
in the
> original Zadoks scale.) The value of the ZSTAGE is used to calculate
TCNP,
> the critical N concentration. My concern is about the values of the
Zadoks
> scale used to develop this algorithm. For example, an  XSTAGE of 1
goes
> from emergence to terminal spikelet initiation. What are the
corresponding
> values of the Zadoks scale? Emergence is at 1 (10). The value for
terminal
> spikelet initiation from the algorithm is 2 (20) which corresponds to
the
> beginning of tillering from the Zadoks scale. Does terminal spikelet
> initiation occur at the beginning of tillering or later on just
before stem
> elongation (jointing, at a Zadoks scale of 3(30))? Similar comments
can be
> made about the other beginning and ending values of the other Zadoks
scale.
> Thanks for your help.
>         Albert Weiss

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