1997 Uniform Regional Scab Nursery for Spring Wheat Parents
 
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 Robert Busch, USDA-ARS, Plant Science Unit, Coordinator
 Hong Ma,  Department of Plant Pathology, University of
           Minnesota (Data analysis and compilation)
 Gary Linkert, Department of Agronomy, University of Minnesota
 
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 The Uniform Regional Scab Nursery was grown for the third time in
 1997, at 6 locations including St Paul (MN), Morris (MN),
 Brookings (SD), Langdon (ND), Prosper (ND) and Morden (MB).
 
 A total of 38 entries were tested including 4 checks (2375,
 Wheaton, BacUp and Oslo), 31 parental lines and 3 durums. Among
 those parental lines, 20 (65%) were derived from Sumai 3 or Ning
 8331 (Chinese-based resistant sources) crosses, and 11 (35%) were
 not.
 
 All entries were planted in single rows or hill-planted with 3
 replicates in each location. Inoculation was conducted by
 scattering infected kernels and/or by spraying the heads with
 macroconidia spore suspension during anthesis (2 x 104 - 10 x 104
 spores/ml). A misting system was used for enhancing disease
 infection.
 
 Visual head symptoms of scab infection and post-harvested visual
 scabby kernel ratings (or % tombstone) based on a standard set
 were assessed. Plot means were used for combined analysis. Each
 location's data are separately presented as well.
 
 Level of disease varied with locations. Location means for
 disease index ranged from 12 (St Paul) to 77% (Prosper), and for
 percent tombstone, from 19 (Morris) to 60% (Brookings). The
 disease index and percent tombstone were not necessarily
 associated across locations (Table 9).
 
 Performances of entries varied with locations. For disease index,
 The Langdon location did not correlate with the other sites (r=
 -0.26 to 0.06), but correlation was fair between other locations
 (r= 0.41 to 0.75). For percent tombstone, correlation between
 locations was good, ranging from 0.47 to 0.87, except for St.Paul
 and Langdon (r = 0.29).
 
 Correlation between disease index and percent tombstone was
 strong (r= 0.70), indicating that breeding for low disease index
 is an essential. This is similar to the result obtained in 1996
 nursery.
 
 Location means of spring wheats derived from Chinese-based
 resistant sources for disease index and percent tombstone were
 significantly lower (p<0.01) than that of those derived from
 non-Chinese parents (Table 9).
 
 Using NIR for DON readings was conducted for St. Paul and Morris
 nurseries. Correlation coefficients between NIR reading and
 percent tombstone within location were 0.70 (St. Paul) and 0.89
 (Morris). Mean of NIR readings of the two locations also
 correlated well with the mean of percent tombstone across all
 locations (r=0.74), indicating NIR reading predicted genotype
 performance across environments.
 
 Several entries with Chinese based resistant sources (95NPY1255,
 95NPY1253, SD-ADB61, SD-ADB9, N97-0326, ND2710, 95NPY1350,
 ND2837, FHB34, MN94346) were low for both disease index and
 percent tombstone (Table 8).