2007 MISSOURI WINTER WHEAT PERFORMANCE TESTS
A. L. McKendry, D. N. Tague, J. K. Solomon

Description of Data Collected

Yield

All rows of each test plot were trimmed 30 inches, measured for length, and harvested using a Kincaid™ experimental plot combine. Recorded grain yields were adjusted to 13% grain moisture on comparable plot areas and reported in bushels per acre based on a 60 pound standard bushel weight. In addition to yields obtained in 2007, two-year averages (2006-07), and three-year averages (2005-07) are provided for those entries tested in the Missouri tests for two or three consecutive years, respectively.

Test Weight and Grain Moisture Content

Test weight (pounds per bushel) and percentage grain moisture were determined for grain from each plot using a Dickey-john GAC 2100b™ grain analyzer.

Plant Height

Plant height was measured in inches from the soil surface to the top of the head, excluding awns if present. Reported values have been rounded to the nearest inch.

Lodging

Lodging severity at crop maturity was rated at all test locations. Plots were rated on a severity scale of 0 to 9 where 0=no lodging and 9=plants in the plot were completely flat.

Winter Survival

Percent winter survival was estimated for each plot after initial spring green-up (approximately Feeke’s GS 6) at all locations. In 2007, winter survival was recorded before the spring freeze that occurred in April. Reported values have been rounded to the nearest percent.

Freeze Damage

Freeze damage was assessed approximately 10 days after record low April temperatures that occurred following jointing of most varieties. Data were taken after winter survival data were taken and reflect leaf burn through stem collapse. Freeze damage was rated on a 0-9 scale with 0 = no visible damage and 9 = 100% of the plants showing leaf burn and complete stem collapse leading to lodging with plants flat on the ground. Specifically, ratings from 1-8 were taken as follows: 1 = 10% visible freeze damage and no lodging; 2 = 20% of the plants have burned leaves with 0-5% lodging; 3 = 30% of the plants have burned leaves with less than 10% lodging; 4 = 40% of the plants have burned leaves with less than 15% lodging; 5 = 50% of the plants have burned leaves with less than 20% lodging; 6 = 60 % of the plants have burned leaves with less than 25% lodging; 7 = 70% of the plants have burned leaves with 30% lodging; 8= 80% of the plants have burned leaves with 50% lodging. Early lines were, in general, more severely damaged than later lines. Recovery was noted in many varieties but yield was significantly impacted. Plots with ratings 7-9 had re-growth from the crown resulting in small, late, and less productive heads.

Heading Date

Heading dates were recorded when 50% of the heads in a plot had extended above the flag leaf collar. Heading dates were recorded in Julian days (number of days after January 1) for statistical purposes. The corresponding calendar dates are also presented. Heading date data for most locations was significantly impacted by freeze damage which compressed the heading window and caused early lines to head later than would be expected for the variety.

Disease Ratings

Barley yellow dwarf virus (BYDV) was present at many locations and was rated as percentage of the flag leaves in the plot showing symptoms. Bacterial stripe, caused by Xanthomonas transluscens was rated as percentage of the canopy showing symptoms.

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