This study found cultivar choice to be the most influential factor for canola emergence percentage. Seeding date also influenced emergence, but this was mainly a function of environmental conditions. All environmental variables influenced emergence, and temperature and heat units were consistently more influential than precipitation and moisture.
Studies have shown that seeding speed and depth, seeding date, seed size, row spacing, crop rotation, and stubble management will influence canola establishment, but results of these studies are inconsistent across Western Canada where environmental conditions are variable and can be significantly yield-limiting. This observational on-farm study was conducted to improve our understanding of the interactive effects of management and environment on canola stand establishment. More specifically, it examined how management decisions and environmental conditions interact to affect:
(1) canola emergence and seedling development.
(2) disease (sclerotinia and blackleg) development.
This approach allowed researchers to examine several intercorrelated factors simultaneously, to better show how field conditions can affect the outcome of management decisions.
This study was conducted on commercial canola fields in collaboration with six local producers around Indian Head, Saskatchewan, from 2018-20.
Environmental and agronomic data (see the table) were collected from several fields throughout the growing season and the producers provided their individual crop management data. Researchers used modelling to examine the additive and interactive effects of management and environment on the speed, temporal uniformity, and spatial uniformity of canola emergence.
Cultivar and soil temperature key for emergence rate
The top-ranking model, which weighted significantly higher than other models, showed an 80 per cent probability that “cultivar” and “average soil temperature 14 days after seeding” were the most influential management and environmental variables on canola emergence rate. The top-weighted model also had a significant interaction between cultivar and soil temperature, indicating that cultivars’ emergence rates were differentially affected by soil temperature.
Cultivar and soil temperature key for early season vigour
The top-ranking model showed a 99 per cent probability that cultivar and average soil temperature 21 days after the seeding were the most influential management and environment variables on canola growth rate. The top-ranked model again included a significant interaction between cultivar and soil temperature.
Higher air temperature, soil temperature, and heat units before and after seeding were associated with earlier emergence and higher early growth rates. Greater precipitation before seeding was associated with a faster growth rate, while higher soil moisture was associated with a delayed start and slower growth rate.
No clear major influence on spatial uniformity
Model weights were lower overall when competing models were compared, indicating that the prediction of spatial uniformity was more uncertain than emergence rate or growth rate, and that the variables measured were more equal in their influence on spatial uniformity. Environmental variables were more influential than management variables overall.
In summary, this study identified canola cultivar and post-seeding date temperature as the two most influential management variables that consistently impacted emergence response variables. Seeding date was also consistently and significantly influential on emergence, however the effect was not additive when combined with environmental variables, indicating that the effect of seeding date was mainly a function of environmental conditions. Temperature and heat units were consistently more influential on emergence than precipitation and moisture.
Overall, the study was valuable in demonstrating the potential of on-farm observational studies in agronomic research. Future expansion of this observational study to different agricultural production regions would benefit producers.
Canola cultivar was the most influential management variable and had a consistent and surprisingly large effect on all emergence response variables. Seeding date was also consistently and significantly influential on emergence, however the effect was not additive when combined with environmental variables. This indicates that the effect of seeding date was mainly a function of environmental conditions. Nearly all the environmental variables measured consistently influenced the emergence response and had additive and sometimes interactive effects with the management variables. Temperature and heat units were consistently more influential on emergence than precipitation and moisture.
The analysis and findings of the study were limited by the level of replication. In particular, conducting the study in a single location limited the range of certain environmental conditions represented in the study. An extension of the study to provide additional replication at several locations would be insightful and would allow for the interpolation of the results to different agricultural production regions. Yet, the study was useful in demonstrating the potential of on-farm observational studies in agronomic research. An extension of the study could focus on particular variables of interest, as identified by canola industry stakeholders.