Steve,

Before you adjust the ecotype values, you should understand the effect of
the cultivar parametersP1V and P1D. These affect response vernalizing
conditions and sensitivity to photoperiod. Although you are dealing with a
spring wheat, most spring wheats have a weak, non-obligate response to
vernalization. Many spring wheats are photoperiod sensitive.

You can improve your calibration if you have data for days to heading or
days to anthesis from multiple years, locations or planting dates. Keep in
mind in calibrating phenology that observer differences (i.e., from person
to person) can differ, especially for maturity.

Best regards,
Jeff

Jeffrey W. White
US Arid Land Agric Research Center, USDA-ARS
21881 North Cardon Lane
Maricopa, AZ 85239 USA
Tel. 1-520-316-6368  ::  Fax 1-520-316-6330
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http://www.ars.usda.gov/pandp/people/people.htm?personid=33167