GrainGenes

ITEMS FROM THE UNITED STATES

COLORADO

COLORADO STATE UNIVERSITY
Department of Agronomy, Ft. Collins, CO 85023, USA.

Winter wheat breeding and genetics. [p. 235-236]

S.Haley, J. Stromberger, B. Clifford, S. Clayschulte, T. Mulat, E. Ball, S. Slough, and A. Brown.

Production conditions and variety distribution. Total winter wheat production in 2000 was estimated at 70.5 million bushels, a 32 % decrease from the 1999 crop. Average grain yield, at 30.0 bu/acre, was the lowest since 1994 and 13 % lower than the 10-year average. The area harvested for grain was estimated at 2.35 million acres, down just slightly from 2.40 million in 1999.

Overall, environmental conditions for the 2000 crop were much less desirable than optimum. The crop began with good establishment in the autumn that was followed by a very mild winter with virtually no winter injury. Bird cherry-oat aphid and greenbug populations were very high south of I-70 throughout the winter, and BYDV symptoms became quite severe by early- to mid-May. Russian wheat aphid populations also were very high in late winter and early estimates of expected damage suggested that 2000 would be the worst year for RWA damage since its introduction in 1987. High rainfall in April, followed by many days over 90°F in May and June, caused dramatic RWA population declines. A damaging freeze in the early morning hours of 13 May affected yields in many production fields and in some of the field trials. Virtually no rainfall was received from 1 May through harvest and the crop finished very poorly. Aside from BYDV and the aphids, no other significant disease damage was observed.

Estimates of planted acreage for the 2000 crop were as follows: Tam 107 - 33.6 %; Akron - 24.3 %; Halt - 6.6 %; Lamar - 5.1 %; Yuma - 3.9 %; Prairie Red - 3.1 %, Yumar - 3.0 %; Prowers - 2.3 %; Jagger - 2.1 %; Baca and Alliance -1.2 %.

Breeding program. In 1999-00, the breeding program conducted field trials at four main locations in eastern Colorado (Walsh, Burlington, Akron, and Julesburg) in addition to the main site located at the ARDEC research facility near Fort Collins. In coöperation with the CSU Variety Testing Program under the direction of Dr. Jerry Johnson, varieties and experimental lines also were tested at six dryland trial locations (Bennett, Cheyenne Wells, Genoa, Lamar, Orchard, and Sheridan Lake) and two irrigated trial locations in eastern Colorado (Haxtun and Rocky Ford). In 1999-00, the former High Moisture Variety Trial (HMVT, primarily northeastern Colorado locations) and Low Moisture Variety Trial (LMVT, primarily southeastern Colorado locations) were merged into a common dryland trial called the Uniform Variety Performance Trial (UVPT).

Despite the very stressful production conditions and the resulting 'compression' of entry yields into an unusually narrow range, very reliable data were obtained from seven UVPT locations. One location (Bennett) was severely effected by a May freeze and late entries performed better. Several experimental lines that performed well in the 1999 dryland trials, particularly CO960603 (a RWA-susceptible 'Akron/Yuma' line), performed very poorly in 2000 largely because of their medium­late in maturity and the effects of the drought and high temperatures. One hard white line, CO940610, continued to perform extremely well but was discarded because of overall unacceptable baking quality. On a more positive note, several experimental lines performed very well and were retained for further testing in both the dryland (UVPT) and irrigated trials (IVPT) and Foundation seed increase. These lines include the following lines in foundation seed increase for potential release in the autumn of 2001.

• CO940611 - a hard white, sister selection of Trego, RWA-susceptible, very high test weight, and good milling and baking quality.
• CO980894 - hard red, herbicide-tolerant derivative of TAM 110, white-chaffed, RWA-susceptible, good test weight, and acceptable milling and baking quality.
• CO980889 - hard red, herbicide-tolerant derivative of TAM 110, red-chaffed, RWA-susceptible, and acceptable milling and baking quality.

Breeding program efficiency. Since 1999, several improvements in the overall effort to improve our efficiency and capacity for handling large numbers of materials have been implemented. Examples of some of these improvements include a relational database system to facilitate improved data and information management, a computerized machine to affix labels for more streamlined seed packet preparation for planting, a barcode-reader system to assist with weighing plot samples at harvest, adoption of hand-held computers (Palm Pilots) for field and greenhouse data collection, and spraying of field-plot alleys with Roundup® in May rather than harvesting the wheat in the alleys with a combine in July.

Public-counterpart collaboration. Beginning in the autumn of 1999, we established structured interactions with the public breeding programs at Texas A&M University-Amarillo, Kansas State University-Hays, and the University of Nebraska-Lincoln. As part of this effort, we now systematically exchange advanced breeding lines and test these at our respective locations. For example, all CSU experimental lines in the UVPT are now grown in a replicated trial at one location in each of the other three states, and we plant a replicated trial of advanced lines from each of the other three programs at one of our locations. From our perspective, the main advantage of this effort is the opportunity to see a greater range of breeding material (and potential parents for crossing) in our own testing environments. In addition to reciprocal testing, we also have reciprocally-shared, early-generation bulk populations (e.g., F2 populations) with Kansas State University-Hays and University of Nebraska-Lincoln.

Web-based variety information. A relational database system was implemented on the internet/World Wide Web (http://triticum.agsci.colostate.edu) to provide complete access to winter wheat variety information and variety trial data. Data from all dryland and irrigated tests since 1990 are included. In addition to information on variety characteristics and summaries from individual trial locations, users can direct the database to provide multi-location/multi-year data summaries based on user-specified criteria and head-to-head comparisons between two user-specified varieties. We hope that this effort will help wheat producers, crop consultants, and extension agents and enhance the variety selection decision-making process.

Graduate student research. Several graduate student research projects are currently underway. Briefly, these include the following important areas of research: inheritance and chromosomal location of a new WSMV-resistance gene, environmental influence and 'genotype x environment' interaction for key noodle quality characteristics, improvement of the 'wheat x maize' doubled haploid system, and identification of the associated advantages and disadvantages of semidwarfing genes (of European origin) that do not reduce coleoptile length.

Stress tolerance research. [p. 236-237]

P.F. Byrne, M.K. Wanous (Augustana College, Sioux Falls, SD), and S.D. Haley.

Because high temperatures and moisture deficits seriously constrain wheat yields in Colorado, we have begun a series of studies to identify the genetic factors controlling tolerance to these stresses. In one of the projects, we are conducting QTL mapping for stress tolerance traits in an RIL mapping population derived from the cross 'Kauz/MTRWA116'. The thermotolerant variety Kauz was developed at CIMMYT/Mexico. Kauz was chosen for this study because of its very good results in membrane thermostability (MTS), tetrazolium reduction (TR) evaluations, and high yields in CIMMYT international trials in hot areas. The thermosensitive parent, MTRWA116, was developed at Montana State University and has resistance to RWA and a desirable plant type for our region. However, its MTS and TR scores contrast strongly with those of Kauz (Table 1).

In a preliminary yield trial, we evaluated a subset of 32 'Kauz/MTRWA116' F2:3 lines together with the parents. The results are summarized in Table 1 with selected correlations among traits listed in Table 2. Significant variation was observed among most traits and indications of transgressive segregation in one or both directions. Interestingly, MTRWA116 had larger kernels, whereas Kauz had a higher kernel number per unit area suggesting that stress tolerance in Kauz is derived from preanthesis events, when the potential kernel number is determined. The correlations (Table 2) indicate that yield was influenced more by kernel number than kernel weight, and that plants that kept their stomates open longer (more negative 12C-13C discrimination) had higher kernel number and yield. The most notable correlation for MTS was with the stay-green trait; lines with better MTS values tended to keep green leaves longer.

These phenotypic results for the population are encouraging, because they reveal considerable variation for characters linked to stress tolerance, as well as for yield traits. Genotypically, the population shows a relatively high rate of polymorphism; parental screening showed polymorphic markers at approximately 50 % of 300 microsatellite loci surveyed. Together these results indicate that the 'Kauz/MTRWA116' RILs are an attractive population for QTL analysis. Large-scale yield trials of the population will be planted in spring 2001.

Measured on ground grain samples with a VG SIRA 10 isotope ratio mass spectrometer. More negative numbers indicate more discrimination against 13C (i.e., stomates are open more).