COLORADO
COLORADO STATE UNIVERSITY
Department of Soil and Crop Sciences, Ft. Collins, CO 85023, USA.
S. Haley, J. Stromberger, B. Clifford, S. Clayschulte, F. Pardina-Malbrán, J. Butler, and M. Collins.
Production conditions, test sites, and cultivar distribution. Total winter wheat production in 2003 was estimated at 77.0 x 10^6^ bu, a 112 % increase from the disastrous 2002 crop but still 4 % lower than the 10-year average. Average grain yield, at 35.0 bu/acre, was 59 % higher than in 2002 and 4 % higher than the 10-year average. The area harvested for grain was estimated at 2.2 x 10^6^ acres, up from 1.65 x 10^6^ acres in 2002.
In 2002-03, the breeding program conducted field trials at four main locations in eastern Colorado (Akron, Burlington, Julesburg, and Walsh) in addition to the main location at the ARDEC research facility near Fort Collins. Overall, environmental conditions experienced at these locations can be described as follows: Akron - adequate yet less than optimal stands from poor planting moisture. Fairly dry winter, very wet spring and early summer. Very high level of stripe rust infection along with leaf rust in entries with good stripe rust resistance. Significant lodging. Very moderate temperatures until the last 10 days before harvest. Very high yields despite stripe rust; Burlington - poor autumn stands resulted from uneven moisture, stands filled in considerably with late autumn and early spring moisture. Fairly dry winter, good early spring moisture, and significant drought stress in May. Good moisture in June saved the trials. Very moderate temperatures until the last week before harvest. No significant disease or insect problems; Julesburg - excellent autumn stands, dry winter, adequate spring moisture, significant dry period around heading, adequate June moisture. Low levels of stripe rust and leaf rust. Some lodging observed. Moderate temperatures until the last 10 days before harvest. Very high yields, though limited by inadequate nitrogen availability (reflected in low grain protein); Walsh - excellent autumn stands, no winter injury, fairly dry winter, adequate early spring moisture, significant dry period from jointing through heading, severe (30-70 % damage) hailstorm 2 weeks after heading in early June, a second significant hailstorm 2 days before harvest. Moderate RWA observed, most likely biotype B based on susceptible reaction of RWA-resistant cultivars; Fort Collins (irrigated) - good autumn stands and moisture. Excellent spring growth, good spring rains reduced need for irrigation. Low levels of stripe rust and leaf rust. Significant RWA observed, most likely biotype A based on reaction of resistant cultivars. Significant lodging observed. Very moderate temperatures until the last 2 weeks before harvest.
In cooperation with the CSU Variety Testing Program under the direction of CSU Extension Agronomist Dr. Jerry Johnson, cultivars and experimental lines were tested at six other dryland trial locations (UVPT - Bennett, Cheyenne Wells, Genoa, Lamar, Orchard, and Sheridan Lake) and two other irrigated trial locations (IVPT - Ovid and Rocky Ford). Overall, both the dryland UVPT and the irrigated IVPT were a drastic improvement over 2002 as a good range of production conditions and yield levels were experienced. Of the total of 10 UVPT locations, four locations were either not harvested or were not used for the overall cultivar summary due to production conditions that prevented reliable data interpretation. The Genoa location was adversely affected by a severe hailstorm near the heading growth stage. The trial at Bennett did not emerge in the autumn, only partially emerged following the 17 March snowstorm, and stands remained highly variable. The Lamar and Sheridan Lake UVPT locations were characterized by uneven emergence, severe spring drought, multiple damaging hailstorms, and extremely low and variable yields. Both the Rocky Ford and Ovid IVPT locations were successfully harvested, although yields at the Ovid location were severely affected by stripe rust, perhaps surpassing the level observed in 2001. Very little virus (e.g., barley yellow dwarf or wheat streak mosaic) infection was observed at any of the testing locations. Russian wheat aphid was observed at higher levels than in recent years at several trial locations. Leaf rust was observed at very low levels at some locations, although at Akron it may have affected yields in those entries that had managed to maintain their leaves in response to the severe stripe rust infection.
Planted acreage estimates for the 2003 crop were as follows: Akron - 22.3 %; Prairie Red - 16.0 %; TAM 107 - 13.0 %; Jagger - 7.7 %; Above - 3.8 %; Yumar - 3.6 %; Lamar and Trego - 3.3 %; Prowers 99 - 2.6 %; Halt - 2.4 %; TAM 110 - 2.3 %; Alliance - 1.8 %; Platte - 1.5 %; Prowers, Yuma - 1.3 %; nd other - 13.8 %.
Elite lines on increase. No new cultivars were released in autumn 2003. In September 2003, however, three experimental lines were put on foundation seed increase for potential release in 2004. The first of these lines, CO980607 (Yuma/T-57//TAM 200/3/4*Yuma/4/KS91H184/Vista pedigree), would be positioned as a higher-yielding replacement for RWA-resistant (biotype A) cultivars including Stanton (from Kansas State), Prairie Red, and Yumar. CO980607 is an awned, white-chaffed, medium maturity, semidwarf HRWW. CO980607 is moderately resistant to stem rust, moderately susceptible to leaf rust, moderately resistant to stripe rust, susceptible to both wheat streak mosaic virus and barley yellow dwarf virus, and resistant to biotype A of RWA. CO980607 was the highest performing entry in the 2003 Colorado UVPT and had the second highest yield in the Southern Regional Performance Nursery (SRPN) across a six-location average of western Great Plains testing locations. Averaged across 17 trial locations of the dryland Colorado UVPT between 2001 and 2003, CO980607 (45.9 bu/acre) yielded slightly less than Trego (47.2 bu/a) but greater than all other entries in the trial, including Stanton and Enhancer (45.0 bu/acre), Above (44.5 bu/acre), Yuma and Alliance (44.3 bu/acre), Ankor and Jagger (41.5 bu/acre), Akron (43.7 bu/acre), Prairie Red (43.0 bu/acre), Halt (42.8 bu/acre), Yumar (42.4 bu/acre), and Prowers 99 (41.1 bu/acre). Average test weight of CO980607 in these trials (58.4 lb/bu) was lower than those of Prowers 99 (59.5 lb/bu) and Trego (59.8 lb/bu), similar to that of Yumar (58.3 lb/bu), and greater than that of Prairie Red (57.5 lb/bu). Milling and bread baking characteristics of CO980607 were determined from field-grown samples from the 2000, 2001, and 2002 seasons. Overall, CO980607 is characterized as having excellent milling properties and average to slightly better than average baking properties. CO980607 was entered for a second year of testing in the 2004 SRPN and for evaluation in the 2003-crop Hard Winter Wheat Quality Council (HWWQC). Approximately eight acres of CO980607 were planted in Colorado in the autumn of 2003 for Foundation Seed production.
The second line on increase, CO00D007 (Yumar//TXGH12588-120*4/FS2 pedigree), is an awned, white-chaffed, medium-early maturity, tall semidwarf HRWW. CO00D007 is a Clearfield™ wheat that has shown dryland yields comparable to Above, improved baking quality characteristics, and resistance to biotype A of RWA. CO00D007 is about 1 day later at heading and 2 inches taller compared to Above. The straw strength of CO00D007 is slightly less than that of Above, similar to that of Akron. CO00D007 was the second highest performing entry in the 2003 Colorado UVPT across a six-location average. Across nine trial locations of the dryland Colorado UVPT during 2002 and 2003, CO00D007 (47.2 bu/a) yielded less than CO980607 (48.0 bu/acre) but greater than all other entries in the trial, including TAM 111 (46.8 bu/acre), Above and Trego (46.7 bu/acre), Ankor (45.8 bu/acre), Yuma (45.3 bu/acre), Prairie Red (45.0 bu/acre), Yumar (43.8 bu/acre), and AP502 CL (43.5 bu/acre). Average test weight of CO00D007 from these trials (58.4 lb/bu) was about 1 lb/bu lower than the trial average, lower than those of Above (59.0 lb/bu) and Yumar (59.3 lb/bu), and similar to that of AP502 CL (58.6 lb/bu). Milling and bread baking characteristics of CO00D007 were determined from a composite of field grown samples from both the 2001 and 2002 field seasons. Overall, CO00D007 is characterized as having slightly below average milling properties and better than average baking properties (especially when compared to Above), in spite of its lower protein and bake water absorption. In autumn 2003, a large Foundation Seed increase (20 acres) of CO00D007 was planted in Colorado. As a backup, a smaller increase (5 acres) of CO00D007 was planted in Yuma, Arizona. CO00D007 also was entered for regional testing in the 2004 SRPN and for evaluation in the 2003 crop HWWQC.
The third line on foundation seed increase, CO991132 (Jagger//TXGH12588-120*4/FS2 pedigree), is a Clearfield™ wheat that shows distinct visual similarity to Jagger. CO991132 did not perform as well as Above or CO00D007 in Colorado but appeared to show promise in other areas of the Great Plains, particularly in Kansas where it outperformed Jagger by 5 bu/acre and the new Kansas State release Overley by 2 bu/acre on a four location average. CO991132 has shown better baking quality scores than Above, but not quite as good as the Jagger parent. In autumn 2003, a 10-acre foundation seed increase of CO991132 was planted in Colorado to allow release of this line in autumn 2004, pending 2004 performance evaluations. As a backup, a smaller increase (five acres) of CO991132 was also planted in Yuma, Arizona. In addition to tests in Colorado, CO991132 was entered for regional testing in the 2004 SRPN and is again being grown along with CO00D007 in Westbred and AGSECO trials in Kansas and Montana.
Samples of all lines on foundation seed increase are being tested for milling and baking quality in our own quality laboratory, the USDA Hard Winter Wheat Quality Laboratory (Manhattan, KS), and various private industry collaborators. The Clearfield™ lines also were planted in replicated Clearfield Qualification Trials in autumn 2003, with five locations in Colorado and two locations in both Oklahoma and Nebraska with our counterparts in those states. As we did not conduct the Clearfield™ qualification trials in 2003, we are hopeful that we will obtain the required data to support cultivar release in 2004.
The trials in 2003 were a drastic improvement over those in 2002. Yield averages ranged from 18.7 bu/acre at Walsh to 90.4 bu/acre at Akron, with a range of different yield levels in between. Although random, nongenetic variability at four locations (Lamar, Sheridan Lake, Genoa, and Bennett) prevented reliable data interpretation from those locations, data from the other six locations were sound and of great value for variety selection and recommendation. Based on agronomic, performance, pest resistance, and end-use quality evaluations, 16 experimental lines were retained and advanced for further testing. Small-scale seed increases of each of the lines retained for further testing were planted in autumn 2003. Seed supply from any of these lines that perform well in 2004 should be adequate to enable Breeder Seed increase in 2004-05 (for earliest possible release autumn 2006). In addition to continued yield testing, extensive milling and baking quality evaluations will be done on these materials during winter 2003-04 in the CSU Wheat Quality Lab, the USDA-ARS Hard Winter Wheat Quality Lab (Manhattan, KS), and by various private-industry collaborators. The Irrigated Variety Trial (IVPT) was planted at three locations in Colorado. Excellent separation among entries was observed at all locations, although marginal stands (due to late planting) and stripe rust adversely affected the Ovid trial location. A few HWW experimental lines performed quite well in the trials, especially CO99W254, which was at or near the top of the trial at all three locations. Although the baking quality of CO99W254 is in question, it is encouraging that we are beginning to identify experimental lines with very high yield potential for irrigated production conditions. Under these conditions, stripe rust may continue to be a concern and so we have begun to focus a bit more on stripe resistance in the crossing program. Good sources of resistance are available in Great Plains germ plasm and these sources should prove useful in the absence of a race change that makes them ineffective.
New Russian wheat aphid biotype. In late March through May 2003, reports were received of severe RWA infestations and plant damage in fields of Prairie Red winter wheat in southeastern Colorado. Infested plants in these fields displayed characteristic susceptible symptoms, raising concern that a new RWA biotype was present. Greenhouse seedling screening experiments with a colony reared from this isolate (provisionally denoted as biotype B) confirmed that it is virulent to all resistant wheat cultivars available in the U.S. hard winter wheat region, including the Dn4-based resistance deployed in several cultivars by CSU and the resistance from PI 220350 deployed by Kansas State University in the cultivar Stanton.
Upon confirmation of the presence of the new biotype, we evaluated a broad collection of resistance sources used in our breeding program. These sources included all previously numbered genes (Dn1 through Dn9) in addition to eight other sources that have not received numbers but had shown promise in evaluations at CSU and elsewhere. With one exception, each of these sources proved to be as susceptible to the new biotype as the Dn4 sources and Stanton. The lone exception, accession 94M370 from South Africa, showed a very high level of resistance to the new biotype. Unfortunately, the resistance in 94M370 is conferred by the Dn7 gene that resides on a T1BL·1RS wheat-rye translocation has been associated with serious adverse effects on bread baking quality. We obtained a group of five lines from the USDA-ARS in Stillwater that carry this resistance and we are currently evaluating these in the field for their release potential.
In separate screening experiments, we also have identified effective resistance from two other sources. The first of these is an experimental line from the USDA-ARS in from Stillwater, OK, designated 2414-11 (derived from PI 366515). The resistance in this source is currently being backcrossed into several elite backgrounds. The second resistance source is a group of lines from our own program that carry resistance from triticale accession PI 386148. The resistance in these triticale-based lines had previously been transferred to a Lamar background, yet we are presently uncertain about the stability of this resistance.
In an attempt to identify additional resistance
sources, we recently completed the first evaluation of a collection
of 761 wheat accessions from the National Plant Germplasm System.
The accessions that we chose to evaluate showed a similar level
of resistance to the original RWA biotype as the resistant cultivar
Halt in systematic germ plasm evaluations conducted by the USDA-ARS
in Stillwater, OK, in the 1990s. From the group of 761 accessions,
we have identified a group of 68 accessions that show promise
for a replicated follow-up evaluation planned for spring 2004.
Only eight of these accessions, however, showed a level of resistance
similar to the resistant check 94M370. Four of these are from
Afghanistan (PI 135064, PI 366566, PI 366572, and PI 366589),
two are from Iran (PI 140204 and PI 429398), one is from Kazakhstan
(PI 572652), and one is from Tajikistan (CI 2401). Initial crosses
have now been made with each of these resistance sources.
With very few resistance sources currently available, additional germ plasm screening is needed. We recently began the evaluation of a group of 7,000 Iranian landrace selections that are relatively new additions to the National Plant Germplasm System. These accessions have been evaluated by other researchers (e.g., CIMMYT, University of California-Davis) for RWA and other agronomic characteristics but have not been evaluated for resistance to the new RWA biotype present in Colorado. As many of the resistant accessions from the original screenings by the USDA-ARS originated from Iran, we expect that this collection will contain at least some resistant accessions.
Our resistance breeding strategy will emphasize the most rapid deployment of resistance possible in a new cultivar. An overriding objective of this effort will be the maintenance of a broad diversity of resistance sources to hopefully be better prepared in the event that additional biotypes are identified.
Several graduate student research projects are currently underway or were completed in 2002-03. Briefly, these projects include the following important areas of research: assessment of the breeding potential of gibberellic acid-sensitive semidwarfing genes that do not reduce coleoptile length (Sally Clayshulte); development of GIS technology to improve cultivar recommendations and identify cultivar-specific production and quality zones (Federico Pardina-Malbrán); identification of RWA biotype-B resistance sources and characterization of field protection provided by the Dn7 RWA-resistance gene (Meghan Collins); and characterization (inheritance, allelism, and marker-tagging) of biotype B RWA resistance sources (Joshua Butler).
We continue to work on backcrossing novel genes into our germplasm base through the multi-institutional grant effort funded by the USDA-IFAFS grant-funding agency. The focus of this grant, entitled Bringing Genomics to the Wheat Fields, is to utilize DNA marker technology as a means to transfer desirable quality and pest resistance traits into released cultivars and elite experimental lines. Our program at CSU is one of 12 public plant-breeding programs involved in this effort, with Dr. Nora Lapitan serving as co-investigator in our effort at CSU. When the program began 2 years ago, we chose recently released cultivars or advanced experimental lines (e.g., Avalanche, Above, Ankor, CO970547, Stanton, and Lakin) as target parents to transfer or combine genes for WSMV and BYDV tolerance (from wheatgrass), high grain protein content (from wild durum wheats), and RWA resistance. We have completed three cycles of MAS and are nearing the stage when improved populations will be grown in the field. Because of the identification of the new RWA biotype, we abandoned our efforts on transfer of the Dn2 and Dn4 resistance genes to different backgrounds. As a replacement for this project, we have begun the marker-based transfer of the Yr5 and Yr15 stripe rust-resistance genes into multiple backgrounds. Continued funding for this project past 2005 will depend on the success of a grant initiative to develop a national effort in MAS in wheat. Coordination of this effort is again through the University of California-Davis.
In 2002-03, we continued our long-term effort to systematically explore wheat germ plasm from CIMMYT-Mexico and eastern European countries. The objective of this effort is to broaden the genetic diversity in our program in order to insure long-term genetic improvement primarily for yield under irrigated conditions and for stress tolerance under dryland conditions. Our strategy for using these sources is to evaluate them under field conditions in Colorado and then select among the larger group for the most promising sources for introgression. The crossing strategy that we are currently using is what we would call a 'focused backcrossing' approach where two or three backcrosses are made with one or two of our elite backgrounds and segregating progenies are identified in field nurseries. We are hopeful that we will identify recombinants that maintain the desirable characteristics of our recurrent parents while transferring in desirable genes from the wheat germ plasm sources.