Spring barley is an important feed crop in eastern Canada, and the development of high-yielding, high grain protein cultivars is desirable . This study was conducted to assess the impact of breeding on the yield and protein aspects of cultivar development, and to identify related changes in plant characteristics which may have been altered over time . A 3-year field experiment was conducted to evaluate twenty six-rowed spring barley genotypes representing the majority of cultivars developed from 1910 to 1988 for eastern Canada . The yields of barley cultivars released from 1935 to 1988 increased at a rate of about 0 .03 t ha ' yr', and showed no evidence of having reached a plateau . Increases in yield were associated with higher total dry matter production and harvest index, reduced plant height and increased lodging resistance . No consistent change in main stem or tiller yield components was observed . Grain protein concentration decreased progressively with time, especially with the newer cultivars . Reduction in grain protein concentration was not associated with lower protein content on a per grain basis, but rather with an increase in the amount of non-structural carbohydrate per grain. Total plant and grain N accumulation showed positive trends with time . No trends were observed for N harvest index, apparent post-heading N uptake, N retranslocation, and retranslocation efficiency . Thus, while the newer cultivars accumulated more total and grain N, proportional N partitioning to the grain was not altered .

Barley (Hordeum vulgare L.) is an important cereal crop in eastern Canadla, where it is used mainly as a source of energy for monogastric animals. A 4-yr field experiment was conducted to evaluate the effects of N application on the yield of spring barley. Three cultivars, Cad· ette, Leger (adapted feed types), and Argyle (unadapted malting type) were grown with 0, SO, 100, 150, or 200 kg N ha-• applied as am· monium nitrate at seeding. Two other treatments consisted of 100 kg N ha-1 at seeding plus 50 kg N ha-1 as ammonium nitrate (broadcast) or urea (foliar spray) applied at Zadoks growth stage 50 (spike emer· gence). Grain yield generally did not respond to N treatments. Sep· arate determination of main stem (MS) and tiller yield components revealed that the lack of response to progressively higher rates of N was due to the stable nature of MS yield components and to the relatively small contribution of tillers to grain yield. Very high levels of N occasionally reduced the grain set and yield of MS spikes. Mean weight per MS grain showed little variation among growing seasons and N treatments. High rates and split applications of N had few significant effects on tiller yield and yield components. Tiller spike densities were consistently low (81-147 spikes per square meter). Tiller spikes produced only 7 to 15 grains, with individual grains weighing 60 to 75% of the weight of MS grains. Previous cropping practices and environmental conditions seemed to affect spike development and grain-set more than application of fertilizer N. S PRING BARLEY is an important cereal crop in easternCanada where it is used mainly as a feed grain for swine and poultry. Unfortunately, the yields of barley are relatively low, often in the order of 3 t ha -1 • Recently, there has been interest in developing intensive management practices for cereal crops in eastern Canada. European experience has clearly demonstrated that small grain cereals have a large yield potential which can be expressed at high levels of N with the proper management practices. These include higher seeding densities, and the use of fungicides and plant growth regulators. Higher plant densities and high rates of N commonly increase the incidence and severity of

Barley (Hordeum vulgare L.) is an important feed crop in eastern Canada. Although the grain is used mainly as a source of energy for monogastric animals, high grain protein concentration (GPC) is desirable. Commencing in 1987, a 4‐yr field trial was conducted at the E.A. Lods Agronomy Research Centre of McGill University to evaluate the effects of N application on the GPC of spring barley. Cadette and Leger, which are adapted feed cultivars, and Argyle, an unadapted malting type, were grown with N rates of 0, 50, 100, 150, and 200 kg N ha−1 broadcast at seeding as NH4NO3. Two other treatments consisted of applying 100 kg N ha−1 at seeding and 50 kg N ha−1 as NH4NO3 (broadcast) or urea (foliar solution) 6 to 10 d after awn emergence. Increasingly higher rates of N applied at seeding increased the amount of protein per grain, thereby increasing GPC. The amount of nonprotein dry matter (DM) per grain was consistent among treatments within seasons. In only one instance did fertilizer N increase GPC by reducing nonprotein DM per grain. Split N treatments increased GPC significantly more than a single application of equivalent N at seeding in only two seasons. A foliar‐applied urea topdressing generally increased GPC more effectively than broadcast NH4NO3. With individual cultivars, the GPC response to N treatments could be explained in terms of protein per grain. Cultivar differences in GPC were not always related to protein per grain. Argyle had the highest GPC values (129.1–160.6 g kg−1), but only because of poor nonprotein DM accumulation per grain.

Bur-uaN, P. AND HuNr, L. A. 1988. Relationships among tillering, spike number and grain yield in winter wheat (Triticum aestivum L.) in Ontario. Can. J. Plant Sci. 68: 583-596. Two field experiments were conducted to examine the relationships between tillering, spike number and grain yield in three winter wheat (Triticum aestivum L.) cultivars.

In cereals, N provided to the developing grains comes from continued N uptake and assimilation after anthesis and from the retranslocation of previously accumulated vegetative N. This study investigated management and cultivar effects on post‐heading N uptake and their relationship with total plant and grain N accumulation and grain protein concentration (GPC). Twenty six‐rowed spring barley (Hordeum vulgare L.) cultivars were grown on a Chateauguay clay soil (fine loamy, mixed nonacid, frigid, Typic Hapludalf) in 1988 under conventional management (recommended N, no fungicide or growth regulator) and on a Bearbrook clay soil (very fine silty, mixed nonacid, frigid, Humaquept) in 1989 and 1990 under conventional and intensive (high N, fungicide and plant growth regulator) managements. Postheading N uptake was generally not related to N concentration and N per plant at awn emergence but was highly correlated with total dry matter accumulation after anthesis and moderately to highly correlated with total plant and grain N per plant at harvest. Postheading N uptake seemed related to the amount of tillering that occurred after anthesis. High‐GPC cultivars did not accumulate more N after heading than low‐GPC cultivars. Nitrogen retranslocation was correlated with total dry matter and N per plant at awn emergence, but the relationship varied with growing season and management. Nitrogen retranslocation and N harvest index were not correlated with GPC. Post‐heading N uptake and N retranslocation were negatively but moderately correlated with each other.