'Snowmass' Hard White Winter Wheat
	Snowmass Field Plot Arapahoe, Colorado June 2009	Snowmass Field Plot Dailey, Colorado (Trial With Severe WSMV Infection) June 2007

• Top dryland yields, comparable to the popular varieties Ripper and Hatcher
• Taller plant stature, about 2-3 inches taller than Hatcher and Ripper
• Straw strength less than Hatcher, but good yield under moderate or limited-irrigation conditions
• Heading date similar to Hatcher, 2 days later than Ripper
• Medium coleoptile, good fall stand establishment, good test weight
• Excellent overall disease resistance package - stripe and stem rust, wheat streak mosaic virus
• Sprout tolerance better than Platte, similar to Trego, less than Danby
• Exceptional milling and bread baking quality characteristics

Description

'Snowmass' (CO03W054-2) hard white winter wheat was developed by the Colorado Agricultural Experiment Station and released to seed producers in August 2009. Snowmass was released based on its resistance to stripe rust and wheat streak mosaic virus, superior milling and bread baking quality characteristics, and adaptation for dryland production in eastern Colorado and the west-central Great Plains. 

Snowmass is an awned, white-glumed, hard white winter wheat (Table 1). Snowmass has medium maturity, 146.8 days to heading from 1 January, similar to Hatcher and two days later than Ripper. Plant height of Snowmass is medium-tall (33.2 inches), approximately 2.5 inches taller than Hatcher and Ripper. Coleoptile length of Snowmass (70.9 mm) is similar to that of Hatcher (72.7 mm) and shorter than that of Ripper (86.3 mm). Straw strength of Snowmass is less than average (6.8 score), statistically similar to Hatcher (5.2 score) and less than Ripper (2.9 score). No objective data are available for winter hardiness of Snowmass but field observations and performance under extremely dry soil conditions during recent winters in Colorado suggest that it is at least adequate for successful production in the central Great Plains region.

Selection History

Snowmass (CO03W054-2) was selected from the cross "KS96HW94//Trego/CO960293" made in fall 1999 at Fort Collins, CO. KS96HW94 is an unreleased experimental line from the Kansas State University wheat breeding program with the pedigree 'Arlin'/KS89H20. Trego is a hard white winter wheat cultivar released by Kansas State University in 1999. CO960293 is an unreleased experimental line from Colorado State University from which the germplasm release CO960293-2 was selected.

Snowmass was developed using a modified bulk breeding procedure. All early generation population and line development was done in the greenhouse or an irrigated field-testing location at Fort Collins, CO. The cross between the parents, designated as cross population X99420, was made in the greenhouse in fall, 1999. The F1 seed was harvested in January, 2000, and immediately planted in a field nursery in mid-February, 2000. Seed from the F1 plants was harvested in bulk in July, 2000, and planted in September, 2000, in an unreplicated F2 bulk nursery. In July 2001, the F2 bulk nursery was harvested with a small-plot combine. A non-selected subsample of the grain was planted in September, 2001, in unreplicated F3 bulk nurseries at Fort Collins and Akron, CO. Based on bulk yield, grain volume weight, and general appearance at Fort Collins and Akron, population X99420 was selected by random sampling of approximately 300 spikes at maturity in July, 2002. Selected spikes were threshed individually and planted in a furrow-irrigated headrow nursery in September, 2002.  

Based on visual appraisal of uniformity and agronomic appearance, experimental line CO03W054 was selected from the headrow nursery as an F3:4 line in July, 2003. Between harvest and planting in August, 2003, five grams of grain from the selected headrow was subjected to protein and hardness analysis via near-infrared reflectance (NIR) spectroscopy and a modified whole-meal sodium dodecyl sedimentation (SDS) method (Dick and Quick, 1983). Based on visual observation of grain properties (size, shriveling, and color) and values for NIR protein, NIR hardness, and SDS sedimentation, CO03W054 was selected and planted in preliminary yield trials in September, 2003. These trials were planted at five locations in Colorado in a single replication with 'Ankor' planted as a common check interspersed at regular intervals throughout the nursery. To account for spatial variation in the unreplicated trials, grain yield of unreplicated experimental lines was expressed using a moving means function and as a percentage of nearby check plots. During winter 2003-2004, lines advanced to preliminary yield trials were evaluated for dough mixing properties with the Mixograph.

Based on grain yield and grain volume weight data from two locations in 2004, plant height, heading date, Mixograph mixing time and tolerance, and agronomic appearance, CO03W054 was selected and evaluated in replicated Advanced Yield Nurseries at seven locations in Colorado in 2005. Prior to harvest in 2005, CO03W054 was subject to line reselection by random sampling 40 spikes from a plot growing at Fort Collins, CO. These reselections were grown in Fort Collins, CO, in 2006.

Based on selection criteria described above, CO03W054 was selected and evaluated in the replicated CSU Elite Trial at six locations in Colorado and five other locations in the High Plains region in 2006. Experimental line CO03W054-2 (Snowmass) was selected from the headrow reselection nursery in July, 2006, as an F6:7 line reselection from CO03W054. Based on performance in trials in 2006, and milling and baking quality evaluations over the winter, CO03W054 was retained and evaluated in 2007 in the CSU Elite Trial, the cooperative Southern Regional Performance Nursery (SRPN), and the statewide irrigated variety performance trial (IVPT). In 2008, CO03W054 was evaluated in the CSU Elite Trial (nine locations in Colorado, five other locations in the High Plains) and in a separate trial with Snowmass and several check cultivars at three locations in eastern Colorado. Based on visual heterogeneity of CO03W054, and superiority of Snowmass over CO03W054 in 2008, line reselection Snowmass was advanced for further testing in 2009 in the CSU Elite Trial, the SRPN, the IVPT, and the dryland Uniform Variety Performance Trial (UVPT).

Seed purification of Snowmass began in the 2007 crop year using visual identification and manual removal of tall and red-chaffed off-types from a bulk seed increase (F6:8) grown under irrigation at Fort Collins. A subsample of grain harvested from the increase in 2007 was used to plant a 0.1 acre Breeder seed increase (F6:9) in 2008. This increase was rogued as in 2007 and was used to plant a 10 acre Foundation seed increase (F6:10) in Yuma, AZ, and a 4.5 acre Foundation seed increase near Milliken, CO.

Yield Performance

Field performance of Snowmass has been determined from various yield trials in Colorado. These are summarized as follows:

• CO03W054 was tested at seven trial locations of the Advanced Yield Nursery in 2005 (Table 2). Mean grain yields of CO03W054 were the highest in the trial and higher than each of the other hard white wheat checks. Average test weight of CO03W054 was right at the average of the trial, lower than each of the check cultivars.
  
  
  
  
  
• CO03W054 was tested for three years in the replicated CSU Elite Trial between 2006 and 2008 (Table 3). In these trials (25 total environments), grain yield of CO03W054 was similar to Ripper and Above, less than Hatcher, Bill Brown, and Thunder CL, and greater than hard white wheats Danby and Avalanche. Test weight of CO03W054 in these trials was average, similar to Above.
  
  
  
  
  
• Line reselection CO03W054-2 (Snowmass) was isolated from CO03W054 in 2007 and the two were tested together in trials in 2008 and 2009. In 2008, Snowmass showed slightly higher yield than CO03W054 with similar test weight (Table 4). In 2009, both lines were tested in the CSU Elite Trial at 12 dryland and 2 irrigated locations in Colorado. Averaged across 12 dryland locations (Table 5), CO03W054 and Snowmass were essentially identical for both yield and test weight.
  
  
  
  
  
  
• Snowmass was tested for four years in the CSU Elite Trial, as CO03W054 from 2006-08 and Snowmass in 2009. In these trials (Table 6), grain yield of Snowmass was lower than Ripper and Hatcher, similar to Thunder CL, and greater than Danby. Test weight of Snowmass in these trials was right at trial average, slightly lower than Hatcher, similar to Thunder CL, and greater than Ripper.
  
  
  
  
• Snowmass was tested for two years in the dryland CSU Uniform Variety Performance Trial (UVPT), as CO03W054 in 2008 (6 locations) and CO03W054-2 in 2009 (10 locations). In these trials (Table 7), Snowmass was the second highest yielding entry on a two year average, slightly lower than Ripper on a 16-location average. In these trials, the test weight of Snowmass was about 1.0 lb/bu over the trial average.
  
  
  
  
  
• Snowmass was tested for three years in the CSU Irrigated Variety Performance Trial (IVPT),as CO03W054 in 2007 and 2008 (6 locations) and CO03W054-2 in 2009 (10 locations). Yield and test weight data are available from 8 total environments, including 3 locations in 2007 and 2008 with CO03W054 and 2 locations in 2009 with CO03W054-2 (Table 8). In these trials, Snowmass was the sixth highest yielding entry on a three-year average, similar to Jagalene and TAM 112. In these trials, the test weight of Snowmass was about 0.2 lb/bu higher than the trial average. While the performance of Snowmass in these trials was quite good, where lodging occurred Snowmass was severely lodged and did not yield well (see Table 1). Thus, Snowmass would not be recommended for irrigation under high fertility, high yielding conditions.
  
  

Disease and Insect Resistance

Disease and insect resistance characteristics of CO03W054 and Snowmass have been determined from cooperative evaluations through the USDA Regional Testing Program and field observations in Colorado and adjacent states. These are summarized as follows:

• Snowmass is resistant to moderately resistant to stripe rust. Under field infection from prevalent stripe rust races in eastern Colorado in 2005 and 2007, the resistance in CO03W054 (3.0 score, n=4 observations; 1=very resistant to 9=very susceptible scale) was similar to Hatcher (2.5 score) and greater than Ripper (8.3 score). In field tests at Rossville, KS, in 2009, CO03W054 and Snowmass were both scored as resistant to prevalent races of stripe rust, with an infection type of 2 (1=resistant, 9=susceptible) and a severity percentage of 2%. In these same tests, Hatcher was scored as 3/15 and Ripper was scored as 8/98. It is not known at this time if the stripe rust resistance in Snowmass is "high temperature adult plant" (HTAP) resistance as that in Thunder CL.
  
  
• Snowmass is moderately susceptible to moderately resistant to leaf rust. Under field infection from prevalent leaf rust races in Castroville, TX, in 2008 and 2009, the disease severity of Snowmass (4.8 score, n=8 observations; 1=very resistant to 9=very susceptible scale) was lower than that of Hatcher (8.0 score) and Ripper (8.1 score). The leaf rust races present in south Texas are considered to be representative of the race structure available for infections further north in the Great Plains.
  
  
• Snowmass is resistant to moderately resistant to prevalent races of stem rust in seedling screening tests, including RFCS, QCCL, and QCCS. Snowmass is susceptible to the Ug-99 race of stem rust (and its derivatives) from Africa.
  
  
• Snowmass is resistant to wheat streak mosaic virus (WSMV), conferred by the CO960293 parent. This source of resistance has been referred to as "temperature sensitive, near-immunity" (Seifers et al., 2006, Temperature sensitivity and efficacy of Wheat streak mosaic virus resistance derived from CO960293 wheat. Plant Dis. 90:623-628). In controlled growth chamber tests with mechanical inoculation, the resistance from CO960293 does not appear to be as effective against the combination of WSMV and the new Triticum mosaic virus (TRMV). In a single field trial in Colorado (Dailey Irrigated Variety Performance Trial, 2007), which was likely infected by a combination of both WSMV and TRMV, CO03W054 was scored as moderately resistant (2.7 score, n=3 observations, 1=very resistant to 9=very susceptible), similar to TAM 112 (2.7 score) and better than Hatcher (5.7 score).
  
  
• Snowmass is susceptible to wheat soilborne mosaic virus/wheat spindle streak mosaic viruses, a complex of viruses with an extremely low level of occurrence in Colorado. Reaction of Snowmass to barley yellow dwarf virus (BYDV, also very low frequency in Colorado) at Rocky Ford in 2009 suggested that Snowmass has good tolerance to BYDV (3.0 score, n=3 observations, 1=very resistant to 9=very susceptible scale), compared to a score of 3.0 for Hatcher and 6.0 for Bill Brown.
  
  
• Snowmass is heterogeneous for resistance to a collection of endemic biotypes of the Hessian fly, susceptible to greenbug Biotype E, resistant to Russian wheat aphid Biotype 1 and susceptible to Russian wheat aphid biotype 2. The Russian wheat aphid biotype 1 resistance in Snowmass originated from CO960293 (from PI 222668, a germplasm accession from Iran).

End-Use Quality Characteristics

Milling and bread baking characteristics of Snowmass were determined in the CSU Wheat Quality Laboratory from multiple individual location grain samples from the 2005, 2006, 2007, and 2008 seasons. Hatcher (hard red winter wheat) and Thunder CL (hard white winter wheat) were included as "good" baking quality checks while the hard white wheat cultivar Danby was included as a "poor" baking quality checks. The evaluations for Snowmass are summarized as follows:

• Values for milling related variables were generally good for Snowmass compared to the check entries, with comparable kernel characteristics and wheat grain protein content. Slightly lower flour extraction was observed for Snowmass, though the differences observed are very small.
  
  
• Values for baking related variables were generally superior for Snowmass compared to Hatcher and especially the poor baking quality check Danby. Similar values were observed for Snowmass and Thunder CL. Snowmass shows very strong dough mixing characteristics (i.e., longer mixograph and bake mix times, higher mixograph tolerance score) and superior functionality in a standard straight-dough pup loaf bake test (i.e., very high loaf volume and superior crumb grain score).

Snowmass was also evaluated in the 2007 and 2008 Wheat Quality Council Testing Program, with Hatcher as a check. In both years, industry evaluators rated Snowmass very favorably, commenting on its exceptionally strong dough mixing properties and overall superior baking quality characteristics.

Multiple pre-harvest sprouting tolerance evaluations have been conducted on CO03W054 and Snowmass. Available data suggest that the pre-harvest sprouting tolerance of Snowmass is slightly less than Danby and Aspen, similar to Avalanche and Trego, and greater than Thunder CL, NuFrontier, and Platte.

Development Team

Scott D. Haley, Jerry J. Johnson, Frank B. Peairs, John A. Stromberger, Emily E. Heaton, Scott A. Seifert, Rebecca A. Kottke, Jeff B. Rudolph, Richard Chen, Bradford W. Seabourn, Bob Bowden, Guihua Bai, Yue Jin, Jim Kolmer, and Xianming Chen

Affiliations

• S.D. Haley, J.J. Johnson, F. B. Peairs, J.A. Stromberger, E.E. Heaton, S.A. Seifert, R.A. Kottke, J.B. Rudolph: Soil and Crop Sciences Dep., Colorado State Univ., Fort Collins, CO 80523
• R. Chen and B. W. Seabourn: USDA-ARS-GMPRC-GQSRU, 1515 College Ave., Manhattan, KS 66502-2736
• G. Bai and B. Bowden: USDA/ARS/PSERU, Kansas State Univ., 4008 Throckmorton Hall, Manhattan, KS  66506
• Y. Jin, J. Kolmer: USDA/ARS/CDL, 1551 Lindig St., Univ. Minnesota, St. Paul, MN  55108
• X. Chen, USDA/ARS/WGQPDR, Room 209, Johnson Hall, WSU, Pullman WA 99164-6420

References and Notes

Breeder seed of Snowmass will be maintained by the Colorado Agricultural Experiment Station. Snowmass has been submitted for U.S. Plant Variety Protection under P.L. 91-577 with the certification option.

Acknowledgements

Snowmass was developed with financial support from Colorado Agric. Exp. Stn. Projects 795 and 646, the Colorado Wheat Administrative Committee, and the Colorado Wheat Research Foundation.