Optimizing Seedling Establishment of Late-Fall Seeded Canola in the Water-Limited, Heat and Drought Stressed Environments

Date: March 2003
Term: 2 years
Status: Completed
Researchers: Yantai Gan, Agriculture and Agri-Food Canada (AAFC) Swift Current, SK; B. Elliott, AAFC Saskatoon SK, K. Topinka, Alberta Agriculture, Food and Rural Development, Edmonton AB; S.V. Angadi and C.L. McDonald, AAFC, Swift Current SK
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a

Project Summary

Low available water, high heat and drought stresses are factors limiting canola productivity in the Brown soil zone of the Canadian prairies where conventional canola has not traditionally been grown. Recent advances in seeding technology have provided producers with opportunity to grow canola in this dry area. The objective of this research is to determine the effects of seed vigour, seed coating and seeding technique on crop establishment and seed yields for fall-seeded and spring-seeded canola in the dry Brown soils of the prairies. On average, canola seeded in the spring produced higher plant populations and greater seed yields than fall-seeded crops and shallow seeded crops performed and yielded the best.

Low available water, high heat and drought stresses are factors limiting canola productivity in the Brown soil zone of the Canadian prairies where conventional canola has not traditionally been grown. Recent advances in seeding technology (i.e., late-fall seeding with polymer coating) have provided producers with opportunity of growing

canola in this dry area. Seeding canola in the late-fall may allow the crop to use the early-spring soil moisture effectively because late-fall seeded crop often emerges from the ground soon after the soil warms up. With its early establishment and growth, fall-seeded canola crop usually flowers 2 to 3 weeks earlier than spring-seeded canola. The early flowering allows canola plants to avoid or reduce the mid-summer heat stress, thus increasing yield potential. However, canola seeded in the late-fall normally germinates and emerges under cold soil conditions the following spring, thus, poor emergence and thin plant establishment often occurs.

The objective of this research is to determine the effects of seed vigour, seed coating and seeding technique on crop establishment and seed yields for fall- and spring-seeded canola in the dry Brown soils of the prairies. Two field experiments were conducted at Swift Current in 2000 and 2001 and a third experiment conducted at Ellerslie, Alberta in 2001.

In two of the experiments, three different seedlots were planted in the fall and the following spring in both years 2000 and 2001. The three seedlots were: (1) seeds harvested from early spring-seeded crops (ES), (2) seeds harvested from late spring- seeded crops (LS) and (3) seeds harvested from late fall-seeded crops (LF) the previous year. All three seedlots were coated with a polymer “Extender” for fall seeding, and were compared with non-coating treatments. In the spring seeding, only non-coated seeds were used. The three seedlots were planted at half inch (12mm), one inch (24mm), and one and a half inches (38mm) seeding depths. The experiment at Ellerslie was identical to the one at Swift Current, except that all fall-seeded treatments used only coated seeds at Ellerslie. In the second experiment, canola with high, medium, and low seed vigour was planted in the fall and then the following spring in both 2000 and 2001 at Swift Current. Fall seeding occurred between October 30 and November 3 and spring seeding between April 23 and May 15.

Fall vs Spring-Seeding

On average, canola seeded in the spring produced a plant population density that was 28% higher at Swift Current and 270% higher at Ellerslie than the plant densities obtained from the fall-seeded crops. At Swift Current in 2000, fall-seeded canola flowered 9 days earlier and matured 10 day earlier than spring-seeded canola and the spring seeded canola produced an average of 8% higher seed yield than fall-seeded canola at Swift Current. At Ellerslie in 2001, there was no difference in flowering and maturity and the spring-seeded canola produced a seed yield that was more than double the seed yield of the fall-seeded canola. Lower seed yields with fall-seeded canola at both sites were mainly due to weather conditions and poor plant establishment (Table 3).

Effect of Seeding Depth

When comparing the effect of seeding depth, the results were very consistent across the study. Canola planted at half inch (12mm) significantly increased plant counts and shortened the time of flowering and maturity. Shallow seeded canola increased seed yields by 17 to 20% at Swift Current in 2002, 42 to 55% at Ellerslie in 2000 and over 80% Swift Current in 2002. Although growers rarely seed at the deeper depths, the actual seed anchoring depth is normally deeper than planned due to a furrow close-up or the uneven soil surface in the field. These results indicate that a depth control in canola production plays a significant role in improving the seed yield and returns in the dry Brown soil zone (Figure 5).

Table 3. Agronomic characteristics of spring- and fall-seeded canola at Swift Current and Ellerslie in 2000, 2001, and 2002.

Plants were not established at Swift Current in 2001 due to extremely dry spring conditions.

Field Performance of Canola with Different Seed Vigour

Results of field experiments showed a consistently higher plant population density for canola derived from a higher seed vigour lot predetermined by tests in the laboratory. This trend of higher seed vigour resulting in higher plant count was consistent when the seed was planted either in the spring or the fall. Seed vigour, however, did not have an impact on the time of flowering or plant maturity and did not significantly affect seed yields at either Swift Current or Ellerslie.

Effect of Different Seedlots

Results showed that ES seed produced a slightly higher plant density than the two other seedlots. At Swift Current, there was basically no difference in seed yields for the canola crops grown from the three different seedlots regardless of seeding time. However, at Ellerslie, the canola crops grown from the ES seed produced 24% higher seed yield than the crops grown from the LS seed when seeded in the fall in 2001. Similarly, the crops grown from the LF seed produced 18% higher seed yield than the crop grown from the LS seed when seeded in the fall. When the three seedlots were seeded in the spring, they did not differ in seed yield. These results indicate that the ES and LF seeds may produce a more vigorous plant and higher seed yields than the LS seed under stressful growing conditions such that encountered in the fall-seeded situation of 2001. When growing conditions become favorable for canola emergence and early growth, then the differences among the three seedlots diminish.