1999 Missouri Winter Wheat Performance Tests
McKendry, Sweets, Wright, Tague, Salzman, Mattas


Statistical Analyses and Interpretation
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Data collected on all traits measured in the soft red winter wheats 
tested during the 1998-99 crop season are presented in Tables 6 
through 15.  Data for the hard red winter wheats are given in Tables 
16 through 20.  Data presented for individual locations as well as 
regional, state-wide and multi-year data for both tests result from 
analysis based on a randomized complete block design. For both soft 
and hard wheat tests, if an observation was missing in one replication 
an adjusted average of the remaining observations (least squares mean) 
was used to approximate the missing observation. Mean comparisons were 
made using Fisher's protected least significant difference (LSD) at 
the 0.05 probability level (p=0.05).  Coefficients of variation (CV%) 
were calculated from the analyses of variance of each location and 
across all locations.

The LSD is used to compare the performance of two specific varieties.  
If the mean of a variety exceeds that of another variety by more than 
the LSD, then the difference observed will be a true difference in 19 
out of 20 instances under conditions similar to those of the test.

Differences in yield between any two varieties are considered 
significant or real only if that difference exceeds the LSD value 
given at the bottom of each column.  Tables 15 and 20 rank the soft 
red and hard red winter wheats, respectively, according to their 
state-wide average.  Overall rank can be very misleading.  Growers 
should be careful to make pair-wise comparisons of results from both 
the appropriate location or locations and the state-wide averages 
before selecting one wheat variety over another for production in 
Missouri.  Variety selection should be based on yield stability in a 
production environment over years and locations.  Where a variety has 
been in the test for two or three years, combined analyses of the 
yield data over years are presented.  In choosing a variety, other 
characteristics such as test weight, heading date and disease 
resistance should also be taken into consideration.  Where disease 
data were not reported in a particular production environment, they 
can be evaluated from locations in which they were rated.