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.

Final grain weight, a component of grain yield in spring wheat (Triticum aestivum L.), is dependent on the rate and duration of the grain filling process. Duration of grain filling also affects time to maturity. This study was undertaken to examine grain weight in relation to rate and duration of grain filling in three spring wheat cultivars (Neepawa, Fielder, and HY320) and to develop statistical methods for comparing grain filling curves. Four field trials were conducted at Saskatoon, SK, Canada, in 1986–1988. Wheat spikes were collected twice weekly from each plot to determine average grain dry wt. The relationship between grain weight and accumulated growing degree‐days (GDD) from anthesis was described a logistic equation. Final grain weight, and rate and duration of grain filling, were calculated from the fitted curves. Univariate and multivariate analyses of variance were used to examine cultivar differences in grain filling. Stepwise multivariate analysis of variance indicated that maximum grain weight was the most important parameter in characterizing the grain filling curves of the cultivars studied. HY320 had the largest grains (37.0–48.2 mg) in all four experiments and, except in 1986, Neepawa had the smallest grains (29.0–34.8 mg; 36.5 mg in 1986). HY320 had the highest rate grain filling (0.129–0.146 mg/GDD) and Neepawa the lowest (0.096–0.122 mg/GDD) in all experiments. Differences in duration of grain filling were not consistent. Multivariate analysis of variance proved to be a useful tool in examining grain filling curves.

aussi une tol6rance envers les autres sels qu'on retrouve couramment dans les sols de l'Alberta. Chez l'agropyre 6lanc6 I'aptitude ir la levde dans une solution nutritive saline r6v6lait une h6ritabilit6 moyenne (61-68%) ce que ouvre la porte aux possibilit6s d'am6lioration g6n6tique par la s6lection.

Grain weight is a component of grain yield and duration of grain filling is a component of maturity. Both are important traits in applied plant breeding and both depend upon the grain filling process. Grain filling has been described by multi-point and two-point curves. Multipoint curves, based on repeated measurements of grain weight during the grain filling period, are much more demanding of labor and laboratory resources than curves based on records of anthesis, maturity, and final grain weight. To evaluate these two methods of measuring grain filling characteristics, we grew II spring wheat cultivars in irrigated and dryland field trials at Saskatoon, SK, Canada in 1989 and 1990. Final grain weight, time to 50% filled, and relative grain growth rate were estimated from logistic curves fitted to grain weights measured twice weekly from anthesis to maturity. Duration of grain filling and average filling rate (harvest grain weight/duration) were estimated from records of anthesis and maturity. Relative grain growth rate was not related to average filling rate (r =-0.01), and was less closely related than average filling rate to harvest grain weight (r 0.08 compared with r = 0.93, P = 0.01). Estimated time to 50% filled was moderately correlated with observed duration (r-0.66, P 0.05) and, compared with observed duration, differences among cultivars were more consistent and less sensistive to environmental influence. Compared with two-point curves, logistic curves provided better estimates of inherent differences in rate and duration of grain filling. However, this advantage does not justify routine use of multi-point curves in plant breeding except where late season stress masks inherent differences in maturity.

. 1990. Dry matter production and nitrogen accumulation in no-till winter wheat. Can. J. Plant Sci. 70 [461][462][463][464][465][466][467][468][469][470][471][472] Norstar winter wheat (Triticum aestivum L.) was examined in 11 trials with the objective of determining the pattern of dry matter and nitrogen (N)