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The wheat stem sawfly (Cephus cinctus Norton) is a major insect pest of spring wheat (Triticum aestivum L.) in the Northern Great Plains of the US and Canadian Prairie provinces. The development of solid-stemmed wheat cultivars has been the main strategy to minimize losses from this insect. Solid-stemmed cultivars generally yield less than hollow-stemmed cultivars of the same era, and there are reports that degree of stem solidness is inversely related to grain yield. Our purpose was to examine the association between stem solidness and other agronomic traits and measure changes in progeny performance from three solid-stemmed parents representing different eras of cultivar development. Random, F4-derived F6 lines were obtained from crosses between solid-stemmed Rescue, Fortuna, and Lew and hollow-stemmed Newana and Thatcher. The random lines plus parents were evaluated in three environments. Changes during time from Rescue to Lew were in the desired direction for days to heading, plant height, and test weight, while stem-solidness score decreased for the parents themselves and in cross combination. Grain yield showed significant gains in two of three environments. A significant solid-stemmed × hollow-stemmed parent interaction was observed for stem solidness score suggesting epistatic gene action in the inheritance of this trait. The only significant associations of stem solidness score with agronomic traits were with plant height in one cross and grain protein concentration in two crosses. Results show the development of high yielding, solid-stemmed cultivars is not limited by undesirable associations between degree of stem solidness and other agronomic traits. Key words: Wheat stem sawfly, solid-stemmed wheat, trait associations

High protein cultivars of spring wheat (Triticum aestivum L.) from eight foreign countries and the United States were used in crosses to provide progeny for a recurrent selection program. After two cycles of selection, 40 lines selected for protein yield and 16 lines selected fro protein percentage were evaluated with parents in yield nurseries at Bozeman, Montana. Lines selected for protein pereentage had the highest protein percentages, protein yields similar to the parents, and grain yields lower than the parents. Lines selected for protein yield had protein percentages intermediate between those of the parents and lines selected for protein percentage, but they had the highest protein yields and grain yields. Protein percentage and grain yield were negatively correlated and protein yield and grain yield were positively correlated for both groups of lines. The data tend to suggest that protein yield may a better selection criterion than protein percentage for plant breeders to use in improving protein productivity, although additional testing of this hypothesis is proposed. Milling and baking data showed transgressive improvement over the mean of the patents in many important quality aspects, indicating that good quality lines can be obtained from crosses involving poor to mediocre quality cultivars.

Glabrous- and pubescent-glumed populations of spring wheat, Triticum aestivum L., were derived by bulking seed from F2 plants and F3 lines. These near-isogenic populations were evaluated at two locations for grain yield and other plant variables and for grain quality. Agronomic data indicated that the gene governing glume pubescence had little, if any, influence on plant productivity. The small quality differences between pubescent and glabrous types, even though significant in a few cases, are considered too small to have a major beneficial effect on a population.

Five spring wheat (Triticum aestivum L.) varieties were fertilized with five N treatments in 1969 and two N treatments in 1970 near Belgrade, Mont. The varieties were chosen to represent short, medium, and tall height levels, and each was evaluated for agronomic and quality response. Grain yields of normal ‘Centana’ and medium Centana were similar, even though medium Centana was 25% shorter and the straw yield was 17% less. There was no variety-by-fertilizer interaction for yield, indicating that the short and medium height types did not respond any better to N fertilizer than the standard height types. Short Centana had significantly less of its protein translocated from plant to grain than tall or medium Centana. Gain protein percentages decreased as the grainstraw ratio increased, suggesting that the amount of top growth is important in extracting nutrients from the soil. Nitrogen fertilizer significantly increased grain protein percentages, and there was a corresponding increase in loaf volnme and grain and texture scores. Baking absorption and mixing time decreased slightly with increasing amounts of N. Water use was similar for the five varieties and increased with increasing rates of N.

Twelve F1 wheat hybrids were evaluated under infestation by Cephus cinctus Norton for plant and quality characteristics. Hybrid plants always had stern-solidness values intermediate between those of the 2 parents, and only where both parents were solid was sawfly culting satisfaetorily controlled in F1 plants. These data suggest that if hybrid wheat is to be resistant in wheat stem sawfly-infested areas, both parents must carry a solid stem. Grain protein and flour absorption values of hybrids were generally low compared with the 2 parents, suggesting that heterosis is not operating for these 2 factors.