Grain Filling in Three Spring Wheat Genotypes: Statistical Analysis

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.