ITEMS FROM THE UNITED STATES

COLORADO

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

J.S. Quick, J. Stromberger, B. Clifford, S. Clayschulte, Y. Zhang, S. Liu, Q.A. Khan, T. Mulat, A. Ibrahim, and B. Erker.

Production.

The 1997 Colorado winter wheat production was 94.1 million bushels, up 34 % from the 1996 crop, and the yield average was 33 bu/A (harvested acreage), up from 32 bu/A in 1996 and slightly above the 5-year average. Serious mite infestations (brown, Banks, and curl) were observed in east central and southeastern Colorado in the autumn and spring. Wheat streak mosaic was widespread in these same areas. Warm, dry conditions also favored a wide distribution of RWAs in the early spring, the worst infestation since 1989. About 25 % of the wheat acreage was sprayed with insecticides. Leading cultivars were TAM 107, Lamar, Yuma, and Akron.

Breeding program.

Halt, the first RWA-resistant wheat developed in the U.S., yielded the same or more compared to predominant cultivars in 1997 on-farm tests in Colorado, Wyoming, and western Nebraska. Halt is an early semidwarf with excellent quality and moderate susceptibility to leaf rust. TAM 110 was the highest yielding cultivar in the 1997 Colorado dryland variety tests.

Selection progress was made for grain yield, grain volume weight, winter hardiness, resistance to shattering, drought tolerance, WSMV resistance, and bread-making quality among approximately 2,000 early generation lines evaluated statewide. Resistance to RWA was determined for the breeding program by field screening of about 8,000 lines using artificial infestation. Molecular markers have been associated with the Dn2 and Dn4 genes conditioning RWA resistance. These markers will help shorten the development time for pyramiding resistance genes in adapted wheats.

Two new wheats, Yumar and Prowers, were released in 1997. They are resistant to the RWA and are the first of their kind to be released after CSU's 1994 unveiling of Halt , the first wheat resistant to the RWA introduced to U.S. farmers. Yumar and Prowers were developed over 8 years by backcrossing the resistance from an old Soviet wheat into the two popular CSU cultivars Yuma and Lamar. Yumar and Prowers will be available to farmers by next autumn. Yumar and Prowers are similar to their parent cultivars. The new cultivars should quickly replace their parents and greatly broaden the adaptation of resistant wheats in Colorado.

The RWA-resistant line TAM 107-R3 is under seed multiplication for probable release in August, 1998. TAM107-R3 was the highest yielding entry in both the 1997 low-moisture dryland and 1997 high-moisture dryland trials, and its milling, mixing, and baking qualities are similar to those of TAM 107. The line contains about 90 % RWA-resistant plants and is being purified further. The spring wheat breeding program began in 1996 with the major objectives of RWA resistance, heat tolerance, and early maturity. The earliest cultivar release date is 2003. F3s are currently in a greenhouse SSD program. A herbicide-resistance program began in 1997 with a grant from American Cyanamid. The first crosses were made during 25-28 July, 1997 and depending on the acceleration of the program, lines could be ready for release in August, 2002, 2003, or 2004.

Personnel.

Jim Quick served as acting Head of the Soil and Crop Sciences Department during 1 July, 1996, - 30 September, 1997, and continues to lead the wheat breeding program. Shuyu Liu joined the program as a graduate student working on inheritance of resistance to the RWA. Yudong Zhang left the postdoc position in September for a full time job.

Publications.

Davis JG and Quick JS. 1998. Nutrient management and cultivar development and selection strategies to optimize water-use efficiency. J Crop Prod 1(2):accepted.

Dong H, Quick JS, and Zhang Y. 1997. Inheritance and allelism of Russian wheat aphid resistance in several wheat lines. Plant Breed 116:449-453.

Khan QA and Quick JS. 1997. Field and greenhouse evaluation of winter wheat for post anthesis drought stress using chemical desiccation. Agron Abstr p. 76.

Johnson JJ and Quick JS. 1997. Colorado wheat performance test results. Colorado Wheat Farmer 39(2):4-6.

Ma ZQ, Saidi A, Quick JS, and Lapitan NLV. 1998. Genetic mapping of Russian wheat aphid resistance genes Dn2 and Dn4 in wheat. Genome (accepted).

Mulat TG and Quick JS. 1997. Yield and yield components of hard white winter wheat lines in eastern Colorado. Agron Abstr p. 72.

Quick JS. 1997. Wheat breeding developments emerge at CSU. Colorado Wheat Farmer 39(1):8.

Quick JS. 1997. CSU releases two new Russian wheat aphid varieties. Colorado Wheat Farmer. 39(3):4.

Quick JS and Nissen S. 1997. CSU developing herbicide resistant wheat seed. Colorado Wheat Farmer 39(3):1.

Zhang Y, Quick JS, and Lui S. 1998. Genetic variation in PI 294994 wheat for resistance to the Russian wheat aphid. Crop Sci 38:accepted.

Zhang Y, Quick JS, and Lui S. 1997. Genetic variation in PI 294994 wheat for resistance to the Russian wheat aphid. Agron Abstr p. 67.