DEVELOPMENT OF EARLY MATURING BRASSICA CARINATA FOR WESTERN CANADA
KEVIN C. FALK
Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, Saskatchewan, Canada S7N 0X2
ABSTRACT
As the global demand for vegetable-based oil and protein products increases, breeders are faced with the task of developing new and improved oilseed germplasm to expand the current acreage. Brassica carinata has the potential to increase the production area. It is highly heat and drought tolerant, has good resistance to several diseases and insect pests, and has a relatively large seed size. Approximately 4000 progeny representing five populations were evaluated in single row replicated nurseries for several agronomic and phenotypic traits. The B. napus canola cultivar AC Excel was used as a check. Considerable variation was observed in most populations for nearly all characters under observation including days to flower and mature, seed yield, plant phenotype, leaf form and colour, pod architecture, petal colour, and shattering resistance. Preliminary observations suggest that a highly productive oilseed crop or crop suitable for molecular farming could be developed for western Canada.
KEYWORDS: Ethiopian mustard, Crucifer, oilseed
INTRODUCTION
As the world demand for vegetable-based oil and protein products increases, plant breeders are faced with the challenge of developing new and improved oilseed germplasm to expand the current acreage. The two canola species, Brassica napus and B. rapa, are adapted to the cool moist northern growing areas of western Canada and have limited use in the typically hotter and drier southern regions. The development of canola quality B. juncea and Sinapis alba will, in all likelihood, contribute to production expanding to these drier regions. Another Brassica species, Brassica carinata, also has the potential to increase the production area in western Canada.
B. carinata is an oilseed crop that is adapted to the highland areas of Ethiopia. It is commonly referred to as gomenzer or Ethiopian mustard. B. carinata is highly heat and drought tolerant, has good resistance to blackleg disease (Gugel et al. 1990), resistance to aphids and flea beetles (Bayeh and Gebre Medhin 1992), relatively large seed size (Getinet et al. 1996) and some accessions have high levels of resistance to alternaria black spot (Yitbarek 1992). Although its adaptiveness to western Canada has not been extensively studied, a preliminary agronomic evaluation indicated that many accessions from Ethiopia were very late maturing and therefore not well adapted to western Canada. Seed yields varied greatly and, on average, B. carinata yielded less than the B. napus check cultivars (Getinet et al. 1996). However, in another study, the yield of B. carinata cv. S67 was not significantly different from B. napus cv. Westar (Falk 1991).
The seed oil content of many Ethiopian accessions evaluated to date is low. On average, oil contents are 6% to 8% lower than the canola species (Getinet et al. 1996). The protein content, however, is generally higher in gomenzer than in canola and the crude fibre content lower, because of its large seed size.
EXPERIMENTAL
The agronomic improvement and assessment of five B. carinata populations was undertaken to develop B. carinata into a new edible oilseed and/or molecular farming species for western Canada. In 1996, populations were sown in isolation blocks and single plants were harvested. Seed from each plant was visually assessed for seed size and colour, and subsequently sown in a replicated (2X) nursery in 1997. Progeny rows were 3 m long with 60 cm spacing between rows and a seeding rate of 100 seeds per row. Progeny were evaluated for days to flower, early and late vigour, seed set, plant phenotype, disease incidence, flower petal colour and days to mature relative to the B. napus cultivar AC Excel, which was sown every 10 rows. At maturity ten single plants from selected rows were harvested individually from one replicate and all rows from all populations were harvested from the remaining replicate. This procedure was repeated in 1998. Furthermore, equal bulks of selected progeny and base populations were tested in replicated full-plot trials at Saskatoon and Scott, Saskatchewan in 1998.
Considerable variation for all phenotypic traits was observed between and within the five populations. Thousand kernel weights ranged from 2.7 g to 5.1 g. Population >A= was generally early to flower and mature but tended to have poorly filled pods with small seeds. Population >B= was shorter than population >A=, but slightly later to flower with short, well filled pods and relatively large seed. Population >C= was generally early to flower and mature and was characterised by having two distinct plant phenotypes; plants were either short with a low branching habit or tall and upright. Population >D= had a large number of late and tall individuals, but most plants were well podded with large seed. Population >E= was the most vigorous of the five populations from emergence to maturity. Progeny were either late maturing with relatively tall stalks (80+ cm) or early maturing with short stalks (20 cm). Many of the short stalked plants branched at or near the soil surface. Population >E= also showed significant variation in leaf and stem colour; plants varied in colour from a glossy light green to a waxy bluish green.
Days to first flower varied from two days earlier than AC Excel in several lines of populations >A= and >B= to approximately 10 days later in population >D=. Populations >C= and >E= were generally intermediate in days to flower. Days to physiological maturity varied considerably more than days to flower. The earliest maturing lines were approximately five to seven days later than AC Excel and the latest matured approximately 21 days later than the check.
Equal seed bulks from each of the populations (base and selected) were tested in replicated multi-location yield trials at Scott and Saskatoon, Saskatchewan in 1998 . Days to flower (DTF) did not vary by more than three days but variation in days to mature (DTM) ranged from zero days in population >B= to six days in populations >A= and >C= (Table 1). DTM was not taken at Saskatoon owing to severe pod stripping by flea beetles. Considerable variation was observed for seed yield between the five populations but only two comparisons between base and selected were statistically significant. Selected populations >A= and >D= at Scott yielded significantly more than their respective base populations. All selected populations tended to yield more than base populations except for >E=. Increased yield in the selected populations was not unexpected since in addition to selection for earliness, populations were selected for improved seedling and mature plant vigour. Considerable variation was also observed for plant phenotype, leaf form and colour, pod architecture, petal colour, and shattering resistance.
CONCLUSION
It appears from these preliminary observations that a highly productive oil and/or protein crop adapted to western Canada could be developed in this species. Furthermore, researchers in the gene manipulation arena have suggested that B. carinata may be a preferred target species within the Brassicas owing to its biological segregation (Chaudhary et al. 1998) and/or ease of transformation (Babic et al. 1998).
ACKNOWLEDGMENTS
This work was funded entirely by Agriculture and Agri-Food Canada, Saskatoon Research Centre. Drs. Getinet Alemaw and G.F.W. Rakow are acknowledged for their stimulating discussions on plant breeding. The technical assistance of Patricia Tampe, Deby Mitchell, Don Rode and Cliff Powlowski are gratefully acknowledged.
REFERENCES
Babic, V., R.S. Datla, G.J. Scoles and W.A. Keller. 1998. Development of an efficient Agrobacterium-mediated transformation system for Brassica carinata. Plant Cell Reports 17:183-188.
Bayeh, M. and Gebre Medhin, t. 1992. Insect pests of noug, linseed and Brassica in Ethiopia. Pages 174-178 in Oilseeds research and development in Ethiopia, Proceedings of the First National Oilseeds Workshop, 3-5 December 1991. Addis Abeba, Ethiopia.
Chaudhary, S., D.L. Parmenter and M.M. Moloney. 1998. Transgenic Brassica carinata as a vehicle for the production of recombinant proteins in seeds. Plant Cell Reports 17:195-200.
Falk, K.C. 1991. Part of a Ph.D. thesis dissertation entitled: ?Heterosis in summer turnip rape (Brassica campestris L.) and cytoplasmic substitution in the genus Brassica@, Department of Crop Science and Plant Ecology, University of Saskatchewan, 51 Campus Dr., Saskatoon, SK, Canada S7N 5A8
Getinet, A., Rakow, G. and Downey, R.K. 1996. Agronomic performance and seed quality of Ethiopian mustard in Saskatchewan. Can. J. Plant Sci. 76:387-392.
Gugel, R.K.,Séguin-swartz, g. and Petrie, A. 1990. Pathogenicity of three isolates of Leptosphaeria maculans on Brassica species and other crucifers. Can. J. Plant Pathol. 12:75-82.
Yitbarek, S. 1992 Pathological research on noug, linseed, gomenzer and rapeseed in Ethiopia. Pages 151-161 in Oilseeds research and development in Ethiopia, Proceedings of the First National Oilseeds Workshop, 3-5 December 1991, Addis Abeba, Ethiopia.
Table 1. Days to Flower, Days to Mature and Seed Yield of Base (B)
and Selected (S) Populations of Brassica carinata (1998).
Population & Days Days Seed Yield
Location to Flower to Mature (g/plot)
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B S B S B S Chg.(%)
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A - Scott 46 43 109 103 336 481 43.2 *
- Saskatoon 54 52 B B 1336 1512 13.2
B - Scott 45 43 106 106 421 484 14.9
- Saskatoon 52 52 B B 1270 1523 19.9
C - Scott 43 42 101 95 461 505 9.5
- Saskatoon 51 51 B B 1402 1580 12.7
D - Scott 45 44 109 105 392 474 20.9 *
- Saskatoon 52 51 B B 1493 1754 17.5
E - Scott 43 43 109 106 482 460 -4.5
- Saskatoon 51 51 B B 1745 1554 -10.9
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* Significant difference (LSD .05) observed between base and selected population.