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Evaluation of Brassica juncea canola

Canola-oil-quality Brassica juncea was jointly developed by the Saskatchewan Wheat Pool and Agriculture and Agri-Food Canada (AAFC) to expand canola-quality production into the drier areas of the southern Prairies. B. juncea canola is considered to be more drought tolerant, more upright and more resistant to shattering than B. napus canola. B. juncea is the same species as oriental and brown mustards. While the first varieties of B. juncea canola were introduced in 2002, AAFC recently revisited B. juncea performance to see how it compares with the new hybrid canolas that now dominate the marketplace.

“We had conducted some earlier research comparing B. juncea [canola] with canola and mustard varieties in the Swift Current area,” explains Dr. Yantai Gan, research scientist with AAFC in Swift Current. “However, we realized we needed to do more research across multiple sites over southwest Saskatchewan and southeast Alberta before we could be comfortable to make any conclusions. Our earlier research did show that B. juncea [canola] can grow in drier, hotter areas and does tolerate the summer heat and drought. B. juncea [canola] is also blackleg resistant and matures more uniformly with less seed shattering compared to B. napus or B. rapa, making straight combining a good option.”

Gan initiated a three-year study with collaborators from 2010 to 2012 across multiple sites in Saskatchewan and Alberta to determine the yield potential of B. juncea canola in comparison with B. napus. The project also examined the suitability and feasibility of straight-combining B. juncea canola and B. napus canola by quantifying seed and pod losses during plant maturity.

Field trials were conducted at four experimental sites in Saskatchewan in 2010 and 2011 (Melfort, Indian Head, Scott and Swift Current), with the addition of another site at Lethbridge, Alta., in 2011. At each location, seven Brassica varieties were compared, including: B. juncea hybrid canola (201045J10), three B. juncea canola varieties (XCEED 8571 CF, XCEED 8570 CF and a genetic line), B. napus canola RR (46P50), B. napus canola LL (5440) and B. juncea condiment mustard (cv. Cutlass). All of the plots were straight combined. Researchers measured plant growth and development, seed yields at harvest, and seed losses and pod shattering at pod maturity.

Figure 1. Difference of the days to 10 per cent flowering among different canola cultivars. Different small letter means significant difference between Brassicas at the level of 0.05. The bold bar in each box is the mean value of the days to 10 per cent flowering of each cultivar. Source:  Dr. Yanti Gan, AAFC, 2013.

“The results showed that B. juncea canola does offer good growing characteristics and traits such as less seed shattering and more uniform maturity,” says Gan. “Under drier spring conditions, B. juncea canola does emerge quicker than canola.”

In the study, mustard had the fastest growing speed to reach to 10 per cent flowering date. Oriental mustard and B. juncea canola 1 variety had similar days to flower, but the other three B. juncea canola cultivars were similar to the B. napus cultivars (see Figure 1). Both canola cultivars showed significant slower growth speed to reach to 10 per cent flower date compared to oriental mustard. Overall, mustard showed the shortest growing period to reach maturity. In the drier growing areas, B. napus reached maturity a bit sooner than the B. juncea canola cultivars, suggesting B. napus may be the better cultivar in short growing areas.

Overall, the yield results were not as good as expected. “Although both B. juncea canola and mustard proved to be suitable for drier areas and able to tolerate drought conditions, their final seed yields did not catch up to the yield of B. napus,” explains Gan. “In the best year, yields of B. juncea were equal to B. napus, but in most cases B. juncea yield was statistically significantly lower.”

Gan adds that until recently, B. juncea hybrids were not available. However, AAFC Saskatoon and Saskatchewan Wheat Pool had developed a successful hybrid by changing the fatty acid profile to that found in B. napus and reducing the erucic acid and glucosinolate levels to the canola standard. “We did have a B. juncea canola hybrid in this project, which we realize is only the initial state of the variety,” says Gan. “As breeders put more efforts on the genetic enhancement for B. juncea hybrids, we are hopeful that yield increases will follow.”

Although B. juncea has proven to be suitable for dry areas, the yields are still the lowest in the drier areas. Reseachers think it is due to other factors, such as the physiological and morphological characteristics of the plants as compared to canola plants. For example, in situations where there is a less than ideal plant population density, B. napus may produce more pods on the plant to help with yield. However, B. juncea canola has a limited ability to produce a sufficient number of fertile pods (i.e., pods with at least one seed). As well, B. napus may have more seeds per pod, but B. juncea canola has a limited number of seeds per pod.

Gan emphasizes that breeders need to look at all yield components, including pods per plant, number of seeds per pod and weight per seed for B. juncea hybrids, as well as to study the plant architecture to determine how yield components would compensate for each other under stressful growing conditions. These will help figure out where the yield potential will come from.

“I think this class of new canola species has a role to play, especially to expand the boundaries of where canola can be grown in Western Canada,” says Gan. “Brassica juncea has lots of good agronomy traits and can become an alternative oilseed crop in those transitional, non-traditional B. napus growing areas of southwest Saskatchewan and southeast Alberta. The next steps will be for breeders to enhance the genetic level of yielding in hybrid B. juncea to reach similar or higher yields than B. napus.”

November 25, 2013  By Donna Fleury