No abstract

Protein is a primary quality component of cereal grains. Protein concentration is influenced by both environmental and genotypic factors that are difficult to separate. In the present study, a series of cultivar and agronomic trials were conducted on several Saskatchewan soil types with the objective of characterizing the influence of genotype and environment on wheat (Triticum aestivum L.) and rye (Secale cereale L.) grain protein concentration and N use efficiency (NUE) for grain protein production. Minimum protein concentration of 95.4 g protein kg−1 dry grain was expressed when cultivars were produced under high productivity conditions on soils with low total plant available N. Minimum protein concentration was maintained until N was no longer the factor most limiting grain yield. At this point, the protein concentration‐N response curve of a cultivar entered an increased phase. Any environmental (e.g., water or time of N availability) or genotypic factor that increased yield potential also increased the amount of N required to initiate the increase phase of the grain protein concentration N‐response curve. Asymptotic maximum protein concentration was determined by both environmental and genotypic factor. Maximum protein concentration at high levels of N varied from 130 to 231 and 107 to 177 g protein kg−1 dry grain for winter wheat and rye, respectively. At low levels of total available N, the NUE for grain protein production approached 80%. The NUE for grain protein production dropped off rapidly for subsequent increments of N fertilizer, approaching zero for maximum grain yield and reaching zero when maximum grain protein yield was achieved. The end of the increase phase of the protein concentration‐N response curve occurred at approximately the same available N level as maximum grain yield. These observations indicate that management systems designed for the production of cereals with high grain protein concentrations will have a very low NUE for grain and grain protein production.

Winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) can be grown successfully in most parts of western Canada if sown directly into standing stubble. However, soil N is usually limiting under this production system. Consequently, 40 field trials were conducted over a range of soil types and environmental conditions to determine yield and other agronomic responses of no-till winter wheat and rye to N fertilizer applied in the spring. Each trial consisted of three to I2 replications with N rates of 0 to 303 kg ha-1 • Nitrogen fertilizer had little effect on days to heading, days to maturity, test weight, and seed weight. Increased N resulted in height increases of up to 25 em in wheat and 8 em in rye in some trials, and decreases of up to 9 em in both wheat and rye in other trials. Winter rye demonstrated a greater N use efficiency and yield potential than winter wheat. The relationships between grain yield (Y) and total available N were best described by modified inverse polynomials, Y = (I -N/903) uN/(N + u/65.8) for wheat, and Y = (I -N/800) uN /(N + u/88.5) for rye, where u represents the upper limit of yield

The introduction of a practical snow management system, which uses direct no-till seeding into standing stubble immediately after harvest of the previous crop, has permitted northward expansion of the North American winter wheat (Triticum aestivum L.) production area to include most of the western Canadian prairies. Twenty-one broadcast ammonium nitrate fertilizer field trials were conducted in Saskatchewan from 1976 to 1986 to determine what influence timing of N fertilizer application had on grain yield, grain protein yield, and grain protein concentration of no-till winter wheat. Time of N application had a significant influence on all three variables in approximately one-third of the trials. Lower grain yield, grain protein yield, and grain protein concentration were attributed to loss of fallapplied N in four trials. In one trial, a prolonged period without rainfall left N temporarily stranded in a dry surface soil layer and lowered yield for early spring fertilizer application. Delays in spring N application also limited grain and grain protein yield-N responses. However, dry spring conditions and late fertilizer applications did not limit grain protein yield to the same extent as it did grain yield. Therefore, increased grain protein concentration was often associated with delayed N availability. Reduced grain and grain protein yield, and increased grain protein concentration were observed for fall and early spring N applications in trials that experienced favorable spring growing conditions followed by a prolonged drought. Under these conditions maximum grain protein concentration ranged from 170 to 230 g kg-•, compared with approximately ISO g protein kg-• dry grain under normal growing conditions. Crop Develop. Centre, Univ. of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N OWO.

No-till seeding into standing stubble immediately after harvest of the previous crop ("stubbling-in") has been employed to successfully produce winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) on the western Canadian prairies. Soil N deficiencies, which result in low grain protein concentrations, are often associated with stubbled-in winter cereals. In the present study, the effect of N fertilization on protein concentration and protein yield of stubbled-in winter wheat and rye was evaluated in 40 field trials conducted over a wide range of soil types and environmental conditions in Saskatchewan, Canada. Grain protein concentrations exhibited sigmoidal responses to N fertilization with minimums of 98.8 and 93.0 and maximums that varied from 130 to 231 and 107 to 177 g protein kg-• dry grain for wheat and rye, respectively. The Gompertz equation was employed to describe the relationship between protein concen-·tration and total available N, providing an average reduction in sums of squares, due to the model, of 96 and 97% for wheat and rye, !respectively. Grain protein yield response to N fertilizer was de-:icribed by an inverse polynomial function that provided an average 1reduction in sums of squares, due to the model, of 99% for both •wheat and rye. Although grain protein concentration was signifieantly higher for winter wheat in most trials, winter rye demon-:;trated a greater N use efficiency for grain production. Higher grain yields for rye compensated for lower protein concentrations, and at •~qual N rates rye produced as much or more protein per hectare than wheat in all comparable trials except two.(SOUTHWESTERN ALBERTA has been the traditional 1 winter wheat production area in western Canada.