Table 1.
Description of environments where field trials were grown.
Environment abbreviation, location, moisture treatment, latitude and longitude, and planting and harvest dates.
Table 2.
Description of photoperiod (Ppd), reduced-height (Rht), and vernalization (Vrn) loci, alleles, and phenotypes evaluated in this study.
Table 3.
Description of multi-locus genotypes at photoperiod and reduced-height loci.
The photoperiod (Ppd) alleles are ‘a’ insensitive and ‘b’ sensitive. The reduced-height (Rht) alleles are ‘a’ tall wild type and ‘b’ semi-dwarf. ‘Het’ is heterozygous at the locus. Of 299 total entries, 285 entries have complete genotypic data at all five loci, and 280 have complete data with all homozygous allele calls.
Table 4.
Number of entries (n) derived during four different time periods, and the proportion of entries in each group with the photoperiod sensitive allele at Ppd-A1, Ppd-B1, or Ppd-D1.
All 285 entries had complete genotypic data at all three loci.
Fig 1.
Box plot of number of days from 1 January to heading of 299 hard winter wheat entries varying for photoperiod insensitive (Ppd-B1a, Ppd-D1a) and sensitive alleles (Ppd-B1b, Ppd-D1b), evaluated in four Colorado environments.
The box describes the minimum, lower quartile (25th percentile), median (50th percentile), upper quartile (75th percentile) values. The notch displays the 95% confidence interval around the median value, and if the notches don’t overlap between two boxes on the same plot, there is strong evidence their median values differ. The interquartile range is described as the upper quartile minus the lower quartile. The whiskers extend to the most extreme data point that is up to 1.5 times the interquartile range from the median value. Outlying points that fall outside of this range are represented as dots. The environments are (A) partial irrigation at Greeley, CO in 2012 (Gr12P), (B) full irrigation at Greeley, CO in 2012 (Gr12F), and (C) Fort Collins, CO in 2013 (Fo13).
Table 5.
ANOVA table for two-gene model estimating the effects of Rht-B1 and Rht-D1 on heading date in a combined analysis across nine environments.
A total of 285 entries with homozygous calls at both loci were included in the analysis.
Table 6.
Allelic effects (number of days) of Rht-B1b in a model that estimated days after 1 January to heading in 285 winter wheat entries grown in nine environments.
The environments are described in Table 1. The model terms were fit separately for each environment. The model effects included environment, Rht-B1, Rht-D1, and Rht-B1-by-environment interaction. The intercept (Int) describes the number of days from 1 January to heading in each environment before the allelic effects are applied. The allelic effect (number of days) at each locus is added to the Int value. The allelic effect of Rht-D1b was -2.68 days and did not have significant interaction with environment.
Table 7.
ANOVA table for the best-fit model, considering effects of environment, Ppd-A1, Ppd-B1, Ppd-D1, Rht-B1, Rht-D1, and their interactions on winter wheat heading date in a combined analysis across nine environments.
The sums of squares were used to estimate the proportion of total variance each term contributed, and the proportion of genetic variance each genetic term contributed. A total of 280 entries with homozygous calls at each allele were included in the model.
Table 8.
Allelic effects (number of days) of gene-based terms included in the best-fit model for winter wheat heading date in each of nine environments, and the proportion of variability (R2) in heading date explained by all terms in each model.
The environments are described in Table 1. The model terms were fit separately for each environment. The intercept (Int) describes the number of days from 1 January to heading in each environment before the allelic effects are applied. The allelic effect (number of days) at each locus is added to the Int value.
Fig 2.
Frequency of photoperiod and reduced-height alleles in wheat entries from three regions of the U.S. Great Plains.
Map shapefiles are open source and freely available from Natural Earth < http://www.naturalearthdata.com>. (A) Geographic distribution of 263 winter wheat entries that originated from the northern (Montana, North Dakota, South Dakota, n = 39 entries), central (Nebraska, Colorado, Kansas, n = 119), or southern (Oklahoma, Texas, n = 105) U.S. Great Plains. (B) Proportion of wheat entries from each U.S. Great Plains sub-region, or combined across all three sub-regions, with the photoperiod insensitive alleles Ppd-A1a, Ppd-B1a, and Ppd-D1a, and semi-dwarf alleles Rht-B1b, Rht-D1b.