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Title: NITROGEN USE AND BIOMASS DISTRIBUTION IN CULMS OF WINTER WHEAT POPULATIONS SELECTED FROM GRAIN-ONLY AND DUAL-PURPOSE SYSTEMS

Author
item MACKOWN, CHARLES
item CARVER, BRETT - OKLA. STATE UNIV.

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2006
Publication Date: 2/23/2007
Citation: Mackown, C.T., Carver, B.F. 2007. Nitrogen use and biomass distribution in culms of winter wheat populations selected from grain-only and dual-purpose systems. Crop Science. 47(2):350-358.

Interpretive Summary: Each year millions of stocker calves graze wheat pastures in the southern Great Plains to add weight before feedlot finishing. Often on more than 50% of these grazed pastures, the stockers are removed in time to allow the wheat to produce a grain crop. This dual-purpose (DP, grazing plus grain) use of wheat offers producers economic advantages not enjoyed by producers that grow wheat as a grain-only (GO) crop. Traditionally, the wheat cultivars used for DP were developed in GO production systems. Biomass distribution and N use traits for 12 sets of populations (each with unique genetic backgrounds) were used to test benefits of tailoring breeding programs for DP wheat. Biomass distribution and N use traits were measured at anthesis and grain maturity in individual culms of mass selected sub-populations derived from GO and DP production systems. Trait differences between DP and GO selections were often absent or only slight as compared to differences due to genetic background. Selections made from the DP environment performed similar to those from the GO environment when grown in either production system. These results will be useful to wheat breeders seeking to develop cultivars suitable for DP and GO use in the southern Great Plains.

Technical Abstract: Beginning in late fall and ending at jointing in early spring winter wheat (Triticum aestivum L.) crops in the southern Great Plains are often grazed by stocker cattle (Bos tarus L.) and then harvested for grain. Traditionally, dual-purpose (grazing plus grain) wheat cultivars are developed from a grain-only production system. Because culms of dual-purpose grown wheat may forfeit productivity gains for grain-only developed cultivars, we evaluated N and biomass traits at anthesis and maturity for 12 sets of subpopulations (each set a unique genetic background) to test benefits of making selections from a dual-purpose system. Sets came from F2 sources and contained a base F3 bulk population and F5 bulk populations mass selected from the F2 within grain-only and dual-purpose production systems. The 12 sets of subpopulations were evaluated in grain-only and dual-purpose systems in 2001-02 and 2002-03. At anthesis, main effects (year, system, genetic background, subpopulation selection environment) were significant for culm dry wt. and N, and flag leaf dry wt. Among selections, differences for these traits were small (2.0-3.5%) with no difference between grain-only and dual-purpose selections, while differences among genetic backgrounds were large (21-30%). At maturity, differences (7.6-20%) for culm, grain and kernel mass, HI, N uptake, grain N, and NHI occurred among genetic backgrounds, while differences among subpopulations were smaller (1.4-4.5%) and significant for only culm, grain and kernel mass, and N uptake. Selections made from the dual-purpose environment performed similar to those from the grain-only environment when grown in either production system.