Items from the United States - Colorado.

ITEMS FROM THE UNITED STATES

COLORADO

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


Personnel changes.

On 1 January, 1999, Dr. Scott D. Haley joined the faculty of the Soil and Crop Sciences Department at Colorado State University, assuming leadership of the winter wheat breeding and genetics program previously directed by Dr. James S. Quick. Scott comes to Colorado State from South Dakota State University, where he had worked as a winter wheat breeder since 1993. Dr. Quick was named Department Head in summer 1998 and will direct spring wheat improvement efforts until summer 2001.

 

Winter wheat breeding and genetics.

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

Production conditions and variety distribution. Winter wheat production was estimated at 103.2 million bushels. Grain yield averages, at 43.0 bushels/acre, set a new record high. The area harvested for grain was estimated at 2.40 million acres, down from 2.55 million last year. Environmental conditions for the 1999 crop were extremely favorable for production. Good establishment in the autumn, a mild winter (with no winter injury), above-average precipitation in early spring, and relatively mild temperatures through grain filling contributed to above-average yield levels. Russian wheat aphid infestations were severe in some areas, particularly in the southeast part of Colorado, and leaf rust was observed earlier in the season and at higher levels than normal.

Planted acreage estimates for the 1999 crop were as follows: Tam 107-39.7 %; Akron-19.1 %; Lamar-7.5 %; Yuma-7.3 %; and Halt-3.9 %.

Breeding Program. The winter wheat cultivar Prowers 99 was released to seed producers in autumn, 1999. Prowers 99 is an awned, white-chaffed, medium-late, medium-tall HRWW similar to Prowers except that it is has improved resistance to the RWA. Prowers 99 was derived from a modified bulk procedure following single-plant selection (during 1997 and 1998) within the cultivar Prowers. In summer 1997, 200 single-plant selections (head selections) were made at random within the cultivar Prowers and planted as headrows in the autumn of 1997 for production of breeder seed in 1998. Seed subsamples from each of these selections was subjected to two cycles (during autumn and winter 1997-98) of standard greenhouse RWA-screening procedures. The first cycle identified 86 plant selections with resistance to RWA. Progeny testing of these plant selections confirmed RWA resistance in 67 plant selections. In summer 1998, seed of these 67 RWA-resistant plant selections was bulked to form Prowers 99 (designated CO98001-MB) for planting of the Foundation Seed increase in the autumn of 1998.

A Colorado experimental line (CO960293) showing a high degree of tolerance to WSMV was identified by Kansas State University wheat breeder Joe Martin in trials at Hays, KS. The experimental line has resistance to RWA derived from PI 222668, yet the source of WSMV tolerance is in question, because resistance has not been identified in screening of PI 222668 (by Dallas Seifers, Kansas State University Virologist). PI 222668 was possibly heterogeneous for the WSMV resistance, as has been shown previously for RWA resistance (e.g., PI 294994). Research studies are underway to determine the inheritance and chromosomal locations of the resistance.

A HWWW breeding effort, initiated in 1994, focused on incorporation of RWA resistance into the HWWW germ plasm base and adopting procedures for noodle-quality evaluation. Approximately 50 % of the program is HWWW at the preliminary yield nursery stage (F6 generation), and two advanced breeding lines (obtained from Joe Martin at Hays KS) are on preliminary increase. Cultivar releases are expected in 2001 and 2004.

A wheat-maize dihaploid production system was adopted in 1997 as a complement to the overall breeding effort. Using this system, lines with RWA resistance and proprietary, nontransgenic tolerance to imidazilonone herbicides were developed and are positioned for cultivar release in 2002. Tolerance to imidazilonone herbicides would allow for selective control of winter annual grassy weeds (e.g., jointed goatgrass, downy brome, and cheatgrass) that are responsible for $25 million USD annual yield losses in Colorado.

 

Spring wheat improvement.

J.S. Quick and A. Ibrahim.

Our project engages in research to improve the quality and performance of spring wheat. Spring wheat could be planted in rotations that include a spring crop, either following winter wheat or following another spring crop such as corn, proso millet, or sorghum. Acreage of rotations including spring crops has increased from about 20,000 to 200,000 acres (based on increase in dryland corn acreage) during the past 10 years. The spring wheat breeding program began in 1996, and the major agronomic objectives are RWA resistance, heat tolerance, and early maturity. The earliest cultivar release date is 2003. A greenhouse SSD program has allowed rapid generation advance, and 600 F5 lines were evaluated in the field in 1999. We are developing cultivars having the following desirable agronomic traits: high yield and test weight with satisfactory kernel appearance; straw height and strength of the type that can maximize yield potential in years with desirable climatic conditions; early maturity and resistance to grain shattering; drought and heat tolerance; and pest resistance, especially to leaf and stem rust, smuts, and RWA.

We started a coöperative project (ATUT-USDA) in 1997 to develop widely adapted, early maturing, spring wheat genotypes with improved drought resistance, heat tolerance, and grain yield to be used in the sandy stressful areas in the south valley soils in Egypt and in the southern Great Plains of U.S. that are subject to frequent periods of drought and heat stresses. Specific objectives are: 1) to evaluate the available wheat germ plasm for morphological, physiological and agronomic traits under favorable and stressful field conditions; 2) to estimate the association between cellular membrane thermostability and agronomic traits, e.g., earliness, yield, and yield components; and 3) to evaluate the genetic gain for combined heat and drought tolerance using a unique selection and crossing scheme to combine these traits with high yield potential.

 

Publications.

  • Clayshulte SR, Stromberger JA, Guir A., Quick JS, Haley SD, Papa D, and Zhang Y. 1999. Production of doubled haploid plants through wheat x maize crosses and their integration in a breeding program. Agron Abstr:80.
  • Haley SD and Quick JS. 1998. Methodology for evaluation of chemical desiccation tolerance in winter wheat. Cereal Res Commun 26:73-79.
  • Ibrahim AM and Quick JS. 1999. Heritability of high temperature tolerance in winter and spring wheat. Agron Abstr:71.
  • Liu S, Zhang Y, and Quick JS. 1999. Chromosome location of Russian wheat aphid resistance genes in wheat germplasms. Agron Abstr:74.