Studies were conducted to evaluate the reportedly high yielding Mexican and European spring wheat (Triticum aestivum L.) cultivars under different management systems under southern Ontario conditions. We evaluated the potential of selections from spring wheat crosses and crosses between spring and winter wheat. Spring wheat yielded 20 to 32% less than spring barley (Hordeum vulgare L.) and 40% less than winter wheat in tests at five locations over a 4-year period. Spring wheat lacked yield stability over years and locations. Tillering capacity, kernels per spike and kernel weight were lower in spring wheat than barley and winter wheat. The weakest component of spring wheat yield appeared to be the 20.6 average number of kernels per spike. A negative relationship was found between tillering and kernels per spike. This and the short period from seeding to maturity often associated with environmental stress may explain why management practices of increased nitrogen fertilization or reduced seeding rate had little influence on grain yield. Seeding delays reduced yields markedly. Spring wheat in southern Ontario appears to be limited by environment so that superior genotypes may not express their full potential. Crosses between spring and winter wheat lines may, therefore, have a greater potential for winter wheat improvement in Ontario than for selection of spring wheat types.

Early stand establishment of winter wheat (Triticum aestivum L.) is essential for efficient production and erosion control in much of the northwest U.S. dryland wheat region. Stand success depends on efficient storage and retention of winter precipitation and thus, on soil management practices which maximize infiltration and minimize evaporative loss during fallow. In this study fall chiseling (25 cm deep) and disking (13 cm deep) were pared with no tillage with respect to the effect on overwinter water storage in the low precipitation (24 cm annually) region of eastern Washington. Tillage effects were evaluated during a mild winter with minimal soil freezing and during a cold winter with runoff conditions from rain and snowmelt on frozen soil. Three spring tillages, sweep cultivation (13 or 20 cm deep) or disking (13 cm deep), were superimposed on each of the fall tillages to evaluate effects on oversummer soil water retention, both deep in the profile and in the seed zone. In addition, these tillages were compared with a chemical fallow treatment with no tillage. During the cold winter, fall chiseling increased water storage markedly and disking to a lesser extent as compared with no tillage (8.7 cm increase' with chiseling, 2.3 cm with disking), but tillage had no effect during the mild winter. September to May storage as percentage of precipitation for this period was 87, 60, and 50% for chiseling, disking, and no tillage, respectively, for the cold winter, and 62% irrespective of tillage during the mild winter. The increase in water stored during the cold winter by chiseling was attributed to improved infiltration properties of the frozen layer associated with this tillage. Storage efficiency with chiseling was greater during the cold winter as compared with the mild winter largely because of differences in the nature of the precipitation. In the mild winter most precipitation fell as intermittent showers, whereas in the cold winter precipitation events were fewer but each was greater in amount. Oversummer soil water loss (May to September) was not influenced by type of spring tillage; amounts lost ranged from 4 to 9% of the total profile water stored in May. Although oversummer loss increased with increases in total stored water, after the cold winter the amount of stored water in the profile at seeding time was still considerably greater for the plots which received fall tillage. Seed zone water at the end of fallow was generally increased with increase in total profile water content, and was higher where spring tillage was used as compared with chemical fallow.