Effects of Seeding Rate on Yields and Yield Components of the Most Popular Wheat Varieties in Alberta Peace Region

21 hours ago
3 min read

Funded by Alberta Grains

Introduction and Objective

Seeding an accurate amount of high-quality seeds is foundational in achieving a correct plant stand and growing a successful cereal crop. The optimum target seeding rate range for spring wheat in Alberta varies between 250 and 400 seeds/m² (25 and 40 seeds/ft²), with the lower end sufficient to attain maximum yields. In comparison, the higher end can provide slight increases in yield, economic return, weed suppression, and aid in crop uniformity (Alberta Grains, 2022).

This trial evaluates the effect of different seeding rates on four wheat varieties. We hypothesized that differences in varieties or seeding rates would influence the outcome of grain yield and grain attributes.

Figure 1. Wheat plots nearing maturity — **Figure 1.** Wheat plots nearing maturity

What We Did

The project was implemented at the Fairview Research Farm. Table 1 gives site history, soil information, treatments, field operations, and data collected for this trial. The experimental design includes a randomized complete block design using four replications in small plots measuring 8m x 1.14m.

For this project, AAC Brandon, AAC Redberry, AAC Viewfield, and AAC Wheatland were chosen as the most popular wheat varieties among growers in the Peace Region of Alberta and seeded at four different seeding rates: 25, 30, 35, and 40 plants/ft². This report highlights the results obtained in the final year of this two-year trial.

Seeding was carried out using a 6-row Fabro Small Plot Drill with disc-type openers on 23 cm row spacing, complete with side banding. The site received about 10" of rainfall for the growing season (April 1 – Sept 30) and about 1,414 Growth Degree Days.

Results

The results of wheat grain yields, height, and various grain attributes are shown in Table 2 below.

Wheat Height and Lodging

Wheat heights ranged from 49 – 65 cm, and variety had a significant effect, but seeding rate did not. AAC Redberry was the tallest of all four varieties at all the seeding rates, while AAC Viewfield was the shortest. AAC Brandon and AAC Wheatland were intermediate in height compared to the other wheat varieties. No lodging was observed with any wheat variety at any seeding rate.

Wheat Grain Yields

Across all four varieties and seeding rates, wheat yields ranged from 25 – 36 bu/ac and averaged just above 31 bu/ac. A significant effect was observed for variety, but no significant effect was found for seeding rate. Grain yields for AAC Redberry and AAC Viewfield decreased as seeding rates increased. Conversely, AAC Wheatland yield increased with higher seeding rates, peaking at 36 bu/ac at 30 plants/sq ft, before declining at higher seeding rates. AAC Brandon, however, showed a decrease to about 29 bu/ac at 30 plants/sq ft, followed by an increase in yield at higher seeding rates. Overall, there was no significant interaction between variety and seeding rate.

Thousand Kernel Weight (seed weight) and Bushel Weight (test weight)

There were significant differences between treatments for both of these two seed attributes. The Thousand Kernel Weights (TKW) generally decreased with the increased seeding rate for all four wheat varieties. AAC Wheatland had the highest TKWs (30.7 grams/1000 seeds), while Viewfield had the lowest TKWs across all four seeding rates. AAC Wheatland consistently had the highest bushel weights at all seeding rates.

Protein Content

Protein content narrowly ranged between 16.1% and 17.7% across the treatments.

Conclusion

Wheat yields averaged 30.5 bu/ac. Variety had a significant effect; seeding rate did not. AAC Wheatland yielded the highest (35.5 bu/ac) with top TKW, bushel weight. Protein generally ranged from 16.1 to 17.7%.