SARDA Ag Research Newsletter December 2022

Impact of seed size and seeding depth on canola establishment and yield

By Surendra Bhattarai, Ph.D., SARDA Ag Research

SARDA Ag Research initiated this project in 2020.

Canola (Brassica napus L.) is one of Alberta’s most widely grown oilseed crops. The costs of establishing canola are high, with seed costs being second only to fertilizer costs. Cultivar development in recent years has produced varieties with different seed sizes that may alter seeding rates and depth recommendations. There were contrasting opinions about the impact of seed sizes and seeding depths on plant establishment and yield from past studies from different parts of the world. Therefore, this study aims to provide producers with information about seed size and seeding depth effect on canola performance in the grey wooded soil zone of the Peace River region of western Canada to improve on-farm productivity and profitability. The specific objectives of this 3-year study were:

1. To determine the impact of varying seeding depths on Alberta canola emergence, establishment and yield.

2. To determine the impact of varying seed sizes on canola emergence, establishment and yield in Alberta.

3. To assess the interaction between seed size and planting depth on Alberta canola emergence, establishment and yield.

The experiment included four seed sizes (extra-small, small, medium and large) and three seeding depths (1 cm, 2.5 cm and 4 cm). The 1000-seed weight determined the four seed sizes. We designed a 3 x 4 factorial arrangement in a randomized complete block design with four replications, equalling 12 treatment combinations.

We found seed size and seeding depth significantly impacted the emergence in the three years of study near Falher, Alberta. The extra-small seeds showed poor emergence, while the other three sizes had similar emergence. With the seeding depth, the seeds sown at 4cm showed poor emergence compared to 1cm and 2.5cm (Figure 1). Seed size, seeding depth and their interaction showed no significant impact on plant height, 1000-seed weight, seed quality and yield. Plant height ranged from 76.2 to 81.6 cm, and 1000-seed weight ranged from 3.92g to 4.16g. The oil content ranged from 47.9% to 48.6%, and the protein content ranged from 22.9% to 23.7%. The seed yield adjusted to 10% moisture ranged from 2462 kg/ha (45.2 bu/acre) to 2686 kg/ha (49.4 bu/ac) (Figure 1). This three-year study (2020-2022) experienced contrasting weather conditions; hot and dry to cool and wet growing seasons. The results of this study provided an opportunity for the canola producers in the Peace River region of western Canada to decide the seeding depth depending on the soil moisture conditions at the time of sowing. However, further multilocation studies in different contrasting weather conditions are necessary.

Plot Walk, July 30, 2020

Figure 1. Average seed yield and emergence of the four different canola seed sizes (large, medium, small and extra-small based on 1000-seed weight) sown at three depths (1 cm, 2.5 cm and 4 cm).