Management for Maximum Economic Yield of Open Pollinated and Hybrid Canola
This research was initiated to determine whether higher yielding hybrid rapeseed (canola) varieties require a higher level of management to express higher yields, compared to older open pollinated canola varieities.
IPNI-1999-CAN-SK24
21 May 2001
2000
Many of the agronomic practices used for canola production were developed prior to 1980, although they have been updated somewhat with new information generated since that time. The check variety in use in 1980 was Regent. Based on relative variety comparisons, some that are currently being grown have much higher yield potential. For example, Quantum, an open pollinated conventional variety has a yield potential that is about 26% greater while, while the yield potential of the herbicide tolerant hybrid variety Invigor 2663 is about 45% greater. This research was initiated to determine whether current agronomic practices are adequate to take full advantage of the higher yield potential.
The study was initiated in 1999, and continued in 2000, with 2 experiments conducted at 3 locations (Scott, Melfort and Indian Head). One experiment focused on the impact of seeding rate, Nitrogen rate, and fungicides. Results from that study indicated that Invigor seed yield was 8% to 16% greater than Quantum when averaged across treatments suggesting nutrient and water requirements should be greater for Invigor 2663. A second study focusing on the impact of N fertilizer rates (0-150 kg/ha) indicated Invigor 2663 yield was higher at all Nitrogen rates than Quantum; suggesting more efficient use of nutrients and water resources.
At Scott Invigor yields were maximized at an N level of approximately 207 kg/ha versus 197 kg/ha for Quantum. At Indian Head, Invigor 2663 did not reach maximum yield at the highest N rate (150 kg/ha), possibly because residual soil N was much lower than at the other 2 locations. Quantum did appear to reach its maximum yield potential of 1947 kg/ha but was 729 kg/ha less than Invigor 2663. At Melfort Invigor 2663 appeared to reach its maximum yield potential while Quantum did not with both cultivars averaging 3043 kg/ha where 150 kg/ha of N was applied.
In the seed rate x N rate x fungicide study at Melfort, where plant densities were substantially reduced as a result of frost, a seed rate X nitrogen level interaction similar to that observed at Indian Head in 1999 was noted. Yield response to increased nitrogen was enhanced at higher seeding rates. The lack of a consistent response across locations and years indicates the interaction may only occur when plant densities are relatively low.
Although sclerotinia infection and estimated yield reductions were low at all locations, Ronilan applied at Scott and Melfort increased average yield by 152 kg/ha. At Melfort where the severity and incidence of infection was greatest Invigor 2663 biomass increased by 1386 kg/ha compared to only 197 kg/ha for Quantum when fungicides were applied.
Preliminary economic analyses showed that near optimum marginal returns occurred when N rates exceeded 100kg/ha. This applied to Invigor 2663 when canola was priced high and either cultivar when canola was priced low, for both N costs scenarios.
While these results underline the importance of following recommended guidelines for seeding rates, nitrogen rates, and fungicides when growing canola they also suggest that hybrid canola may require different management practices to take advantage of their higher yield potential. However, yield responses to additional N, higher seed rates, or fungicides may be highly dependent on soil and climatic conditions. Results to date, while inconclusive do provide a strong indication that higher yielding cultivars use nitrogen more efficiently, but may also require more N to achieve optimum yield. Results from research to be conducted in 2001 are expected to substantiate these claims and assist in identifying conditions under which yield responses are more likely to occur.