Open-pollinated Canola Research Articles

Yield stability and adaptability of canola (Brassica napus L.) in multiple environment trials

Selecting high yielding genotypes with stable performance is the breeders’ priority but is constrained by genotype × environment (G×E) interaction. We investigated canola yield of 35 genotypes and its stability in multiple environment trials (MET) in south-western Australia and the possibility to breed broadly-adapted high yielding genotypes. The Finlay–Wilkinson (F–W) regression and factor analytic (FA) model were used to investigate the G×E interaction, yield and genotype stability and adaptability. The cross-over response in the F–W regression, substantial genetic variance heterogeneity, and the genetic correlations in the FA model demonstrated substantial G×E interaction for yield. Cluster analysis suggests low, medium and high rainfall mega-environments. F–W regression indicated that genotypes with high stability (e.g. low regression slope values) produced relatively low yield and vice versa, but also identified broadly adapted genotypes with high intercepts and steep regression slopes. The FA model provided a more detailed analysis of performance, dividing genotypes by positive, flat or negative responses to environment. In general, early flowering genotypes responded negatively to favourable environments and vice versa for late flowering genotypes. More importantly, a few early flowering hybrids with long flowering phases were consistently productive in both low and high yielding environments, showing broad adaptability. These productive hybrids were consistent with those identified earlier by high F–W intercept and slope values. Hybrids were higher yielding and more stable than open-pollinated canola, as was Roundup-Ready® canola compared to the three other herbicide tolerance groups (Clearfield®, Triazine tolerant, conventional). We conclude that yield stability and high yield are not mutually exclusive and that breeding for broadly adapted high yielding canola is possible.

Genotypic variation in the accumulation of water-soluble carbohydrate in canola and its potential contribution to seed yield in different environments

Water-soluble carbohydrates (WSC) stored in the stems and pod wall in canola (Brassica napus L.) can be an important source of assimilates contributing to yield. However, genotypic variation in WSC and its contribution to yield have not been investigated. The aims of this work were to quantify genotypic variation of WSC and the extent to which WSC contributes to seed yield. We measured the concentration and content of WSC in a number of hybrid and open pollinated triazine tolerant (TT) and non-TT canola genotypes at flowering, podding and maturity from 2009 to 2011. There were significant repeatable differences in WSC concentration among genotypes (28–108mgg−1 at podding) and WSC content (12–113gm−2 at podding). The major difference in WSC content occurred between the TT and non-TT canola while the difference between hybrid and open-pollinated canola was small. On average, non-TT canola produced higher amount of WSC (68gm−2) than TT canola (47gm−2). Seed yield increased with the increased amount of remobilized WSC in the limited water-stressed conditions (2009 and 2011). Despite the high amount of WSC in drought (2010) year, no significant relationship was found between yield and the remobilized WSC because the higher WSC was offset by yield penalty from delay in flowering in these varieties. The contribution of WSC to yield was higher in drought (10–22%, 2010) year than in the average (3–9%, 2009) and above-average (7–12%, 2011) rainfall year. Genotype and environment interaction was relatively small compared to genotype effect. The difference in the amount of WSC between the herbicide tolerant groups and among genotypes was repeatable and the rankings of genotypes for WSC remained similar across the years. Both the WSC content and the ratio of remobilized WSC to yield had large broad-sense heritability (H=0.68–0.85). The high heritability, the positive relationships between seed yield and WSC under limited water stress conditions, and the high contribution of WSC to yield under drought conditions suggest that WSC could be used as a breeding trait to augment yield in the limited water-stress condition and maintain yield under drought conditions by reducing the effect of water stress on yield.

UA AlfaGold Clearfield herbicide-tolerant spring Brassica napus canola developed from winter × spring canola cross

UA AlfaGold is a Clearfield herbicide tolerant Brassica napus L. open-pollinated canola cultivar developed from a winter × spring B. napus canola cross and registered in Canada in 2015. On average, UA AlfaGold yielded 12.6% more seed but flowered and matured three days later than the WCC/RRC check cultivars. This cultivar had 0.6% higher oil in seed and 0.2% higher protein in meal than the WCC/RRC checks, and rated as resistant to blackleg disease. Development of UA AlfaGold demonstrates the utility of the European winter B. napus canola gene pool in the breeding of spring B. napus canola.

Heterosis of juncea canola under terminal drought conditions

To determine the levels of heterosis in F1 hybrids of juncea canola under well-watered and water deficit conditions, glasshouse experiments were conducted at the University of Melbourne, Parkville campus between 2012 and 2014. Three juncea canola hybrids, their parents and an open-pollinated juncea canola control cultivar (OasisCL) were grown. Plants were subjected to two treatments—well-watered and water deficit after first open flower to maturity. Measurements were recorded on days to various phenological stages, biomass production, seed yield and yield components. Yield heterosis was determined as superiority of F1 hybrids over mid parent and better parent. Two juncea canola hybrids—HJM1Z-2013 and HJM1Z-0027 out-yielded OasisCL and showed significant mid parent and better parent heterosis for seed yield under water deficit. Number of pods per plant was the major yield component affected by water deficit whereas seeds per pod, thousand seed weight and harvest index were stable. Water deficit had significant negative effects on biomass production at harvest. The study revealed the possibility of exploiting yield heterosis of juncea canola under terminal drought conditions. However, further experiments are recommended to verify the results as the results were from pot experiments in controlled conditions.

Relative yield and profit of Australian hybrid compared with open-pollinated canola is largely determined by growing-season rainfall

Australian canola growers have new technology options including hybrid and herbicide technologies, which have offered yield and profitability advantages in other canola-growing regions of the world. This study compared the yield and gross margins of hybrid and open-pollinated (OP) canola from different herbicide tolerance groups: triazine-tolerant, Roundup Ready, Clearfield and conventional across a wide range of environments in south-western Australia, and in the National Variety Trial network in southern Australia to investigate the relative advantages of these technologies. There were significant differences in yield responsiveness between hybrid and OP canola, the magnitude of which was determined by the growing-season rainfall/available water to the crop. Hybrid out-yielded OP canola in favourable environments where rainfall was high and the growing season was long. However, in areas of low rainfall where yield potential was low, hybrids showed little yield advantage over OP. In contrast, there were no differences in yield response between the four herbicide tolerance groups across the rainfall zones. The economic analysis showed that the break-even yield for hybrids versus OP canola was 1.25 t/ha for triazine-tolerant canola, 0.7 t/ha for Roundup Ready canola, and 1.7 t/ha for hybrid Clearfield canola. The gross margin analysis suggested that hybrid triazine-tolerant, Clearfield and Roundup Ready canola was more profitable than the OP system in the medium (growing-season rainfall of 265–330 mm) and high (330 mm) rainfall environments, but not profitable in the lower (<265 mm) rainfall area because the cost associated with hybrid seed outweighed the small yield benefit. The sensitivity analysis indicated that ± 10% changes in canola price and seed cost shifted the break-even yield by ± 0.1 t/ha. Our study makes a case for Australian canola breeders to maintain OP canola varieties, rather than shifting their focus entirely to hybrids, to underpin continued productivity and profitability in lower rainfall areas.

Nitrogen responses of canola in low to medium rainfall environments of Western Australia

Canola (Brassica napus L.) is widely grown throughout all rainfall zones in south-western Australia. Yields are low by world standards, and variable in low-rainfall (<350 mm annual rainfall) and medium-rainfall (350–450 mm) zones, so that minimising production costs is a major consideration for growers in these areas. One of the major input costs is nitrogen (N) fertiliser. Fifteen N rate × application time × canola plant-type experiments were conducted in the low- and medium-rainfall zones between 2012 and 2014. In most experiments, five rates of N were tested, of ranges 0–75, 0–100, or 0–150 kg N/ha. Nitrogen was applied at four different times (seeding, or 4, 8 or 12 weeks after sowing) or split between these timings. Each experiment compared triazine-tolerant (TT), open-pollinated (OP) canola with Roundup Ready (RR) hybrid canola, and one experiment included TT hybrid and RR OP canola types. On average, RR hybrid produced 250 kg/ha, or 23% more seed and 2.2% more oil than TT OP canola, and the average gross margin of RR hybrid was AU$65/ha more than TT OP. However, seed yield and gross margin differences between RR hybrid and TT OP canola were reduced when seed yields were <1400 kg/ha. Canola growth (dry matter) and seed yield responded positively to N fertiliser in most experiments, with 90% of maximum seed yield achieved at an average of 46 kg N/ha (s.e. 6). However, 90% of maximum gross margin was achieved at a lower average N rate of 17 kg N/ha, due primarily to the relatively small yield increase compared with the reduction in concentration of oil in the seed with N applied. Because canola growers of south-western Australia are now paid an uncapped premium for canola grain with oil concentration >42%, decreases in oil percentage have a significant financial effect, and recommended rates of N should be lower than those calculated to optimise seed yield. In 80% of cases, the first 10 kg N/ha applied provided a return on investment in N >$1.50 for every $1 invested. The next 20 kg N/ha applied provided a return on investment of $1.25 for every $1 invested 80% of the time, and further increases would most likely break even. The timing of N application had a minor effect on yield, oil and financial returns, but delaying N application would allow farmers to reduce risk under poor conditions by reducing or eliminating further inputs. Overall, our work demonstrates that a conservative approach to N supply mindful of the combined impacts of N on yield and oil is necessary in south-western Australia and that split and delayed applications are a viable risk-management strategy.

Optimising canola establishment and yield in south-eastern Australia with hybrids and large seed

April sowing of canola is considered optimal for grain yield in many regions of Australia; however, there is often insufficient rainfall in April to sow seed into moisture at the ideal depth of 15–30 mm. We report a series of experiments that investigated the seed characteristics (cultivar type and seed size) that would facilitate successful canola emergence from relatively deep sowing (>30 mm). Ten canola cultivar by sowing depth experiments, each with three hybrid and three open-pollinated cultivars, found hybrid cultivars were able to maintain higher emergence rates and grain yield compared with open-pollinated cultivars from deep sowing. Further investigations in the glasshouse showed that the emergence advantage of the hybrid cultivars was largely due to their inherently large seed size, as increased seed size also improved emergence of open-pollinated canola. Early biomass accumulation also improved with larger seeds. In a field experiment, larger seed size of both hybrid and open-pollinated canola increased early biomass accumulation and final grain yield. Simulation modelling in New South Wales demonstrated the importance of timely sowing of canola, as delayed sowing caused a larger reduction in grain yield than reduced plant population. Although ‘moisture-seeking’ (placing seed into moist soil below a layer of dry soil) reduced the emergence rate of canola, the reduction could be offset by planting large seed (>2 mm diameter). This practice of ‘moisture-seeking’ large-seeded canola should be considered as a strategy to improve the timeliness of establishment and subsequent grain yield of canola when rainfall for crop establishment is marginal yet there is moisture available deeper in the seedbed.

Seed yield of canola (Brassica napus L.) is determined primarily by biomass in a high-yielding environment

The better performance of hybrid canola compared with open-pollinated triazine-tolerant canola can be associated with greater biomass and harvest index. We compared several hybrid and open-pollinated canola cultivars in field conditions to (i) quantitatively analyse yield formation and identify the key drivers of yield formation process; (ii) investigate biomass accumulation and partitioning and evaluate the relative importance of biomass, harvest index and yield components. Six elite varieties, two from each of the three types (triazine-tolerant (TT), hybrid TT, and hybrid imidazolinone-tolerant (IT) or conventional (CV) (hybrid IT/CV)) of canola, were grown under the optimum crop management in the 3 years from 2009 to 2011 in the high-rainfall zone of south-western Australia. Leaf area, specific leaf area, light interception, biomass, seed yield and yield components were measured at key growth stages to determine biomass accumulation, crop growth rate (CGR), radiation-use efficiency and to investigate the relationship between yield, biomass, CGR, specific leaf area, yield components and harvest index. Hybrid IT/CV canola grew more vigorously with thicker leaves and greater leaf area, allocated more biomass into leaves, intercepted more radiation, produced higher biomass in the vegetative stage and maintained its biomass superiority throughout the whole crop cycle. It had radiation-use efficiency of 1.74 g MJ m–2 photosynthetic active radiation, 28% higher (P < 0.001) than TT canola (1.41 g MJ m–2 photosynthetic active radiation) and 16% higher (P < 0.001) than hybrid TT canola (1.52 g MJ m–2 photosynthetic active radiation). The average CGR for hybrid IT/CV canola (12.1 g m–2 day–1) was 32% higher than that of TT canola (9.2 g m–2 day–1) from budding to the beginning of pod filling. Hybrid IT/CV canola produced 38% higher seed yield than TT canola in favourable growing conditions (2009, 2011). However, there was no yield difference between the hybrid IT/CV, hybrid TT, and TT canola in the drought year (2010). The number of pods m–2 and seeds m–2 was highly associated with biomass at vegetative, budding, flowering, podding and maturity and CGR from budding to podding. High yield in hybrid canola was attributed mainly to higher biomass from each phenological phase from the vegetative stage to maturity and not to improved harvest index.

Seed Ethanol Emission and Radicle Protrusion are Better Measures of Canola-Seed Vigor Than Standard Germination

Results of a seed vigor test based on ethanol emission (EE) were compared to rate of emergence (Em50), extent of emergence, seedling mass, and leaf area for 64 lots of open-pollinated and hybrid canola (Brassica napus L.) seed in field plots. The EE test was evaluated against other measures of seed vigor, specifically days to 50% radicle protrusion (R50), 2-d radicle protrusion (R2), seedling fresh mass in hydroponics, cold germination, and a vigor index. Correlation coefficients for R50, R2, and EE versus Em50 were ≥ 0.8 and consistently better than those for standard germination (SG, normal seedlings) for open-pollinated and hybrid propagation types in both the 80%–100% and 90%–100% SG ranges. In contrast to Em50, other aspects of field vigor were not well correlated with vigor tests. It is suggested that EE and R2 are suitable for providing seed quality information to supplement SG results.

Seeding depth and seeding speed effects on no-till canola emergence, maturity, yield and seed quality

Harker, K. N., O'Donovan, J. T., Blackshaw, R. E., Johnson, E. N., Lafond, G. P. and May, W. E. 2012. Seeding depth and seeding speed effects on no-till canola emergence, maturity, yield and seed quality. Can. J. Plant Sci. 92: 795–802. Canola seed costs are substantial, but only a relatively small proportion of planted seeds actually emerge as seedlings. Direct-seeded (no-till) experiments were conducted from 2008 to 2010 at four western Canada locations [Lacombe AB (2007–2010), Lethbridge AB, Indian Head SK, and Scott SK] to determine the influence of cultivar (hybrid vs. open-pollinated), seeding speed (6.4 vs. 11.2 k h−1), and seeding depth (1 vs. 4 cm) on the emergence, maturity, yield, and seed quality of glyphosate-resistant canola. Canola emergence density was positively associated with precipitation levels surrounding the time of seeding; other site and environmental predictors such as soil temperature, soil texture, soil organic matter, latitude and longitude did not consistently influence canola emergence density. The agronomic performance of hybrid canola, including seed yield and quality, was usually superior to open-pollinated canola, but there was no difference in emergence density between the two cultivars. However, the hybrid cultivar emerged 1 d earlier, grew faster and covered the ground more quickly than the open-pollinated cultivar; important results from a crop-weed competition standpoint. Although seeding depth did not influence average canola yield, it often had a major impact on canola emergence density. Under moist conditions, average canola emergence improved from 37 to 62% as seeding depth decreased from 4 to 1 cm, respectively. Seeding at a depth of 1 vs. 4 cm also decreased days to emergence, increased canola ground cover, decreased days to flowering and days to maturity and tended to decrease green seed levels. Relatively high canola emergence rates can reduce the need for additional herbicide applications, herbicide input costs and selection pressure for herbicide resistance. Relatively high canola stand densities can improve the ability of canola to successfully tolerate and accommodate biotic and abiotic stress.

Nitrous oxide emissions in response to ESN and urea, herbicide management and canola cultivar in a no-till cropping system

Environmentally Smart Nitrogen (ESN), a type of polymer-coated urea, synchronizes N release with crop demand to increase N use efficiency and potentially reduce N 2O emissions. This study investigated the effects of ESN and weed management on N 2O emissions from soil under a canola ( Brassica napus L.) no-till cropping system. The experiment was conducted from 2005 to 2008 at three sites: Lethbridge, Lacombe, and Beaverlodge, located in southern, central and northern Alberta, Canada. Treatments included a hybrid and an open-pollinated canola cultivar, with ESN and urea applied at 1 and 1.5 times (×) the recommended rate, and herbicide at 50 and 100% of registered in-crop application rates. Canola was grown in rotation with barley ( Hordeum vulgare L.) and both phases of crop rotation were present each year. The N 2O fluxes from soil were measured using vented static chambers at 2-week intervals during the growing season from 2006 to 2008. Except for a few occasions with higher fluxes from urea than ESN earlier in the growing season and higher fluxes from ESN than urea later on, N 2O fluxes were similar among all treatments for all three years and three sites. The N 2O fluxes also varied over the growing season, and peak flux occurred in response to rainfall events. Similarly, cumulative N 2O emissions, expressed as either per land area or per canola seed yield, over the three growing seasons were low (0.15–2.97 kg N ha −1 yr −1 or 0.05–1.19 g N kg −1 seed) for all treatments and sites, and unaffected by weed management or crop variety ( P > 0.05). The N 2O emission across the three sites from ESN averaged 20% lower ( P = 0.040) than from urea although the differences between fertilizer types or application rates were not significant ( P > 0.05) at each site. Elevated N 2O emissions (72% higher; P = 0.028) from 1.5 × ESN (0.83 kg N ha −1 yr −1 or 0.33 g N kg −1 seed) relative to 1 × ESN (0.26 kg N ha −1 yr −1 or 0.16 g N kg −1 seed) were only observed at Beaverlodge while emissions were similar ( P > 0.05) at the other two sites. The higher N 2O emissions at 1.5 × ESN at Beaverlodge were due to excess N accumulation in soil caused by unfavourable weather conditions that reduced canola N uptake and yield. Our results suggest that ESN fertilizer could reduce N 2O emissions in Alberta, Canada, but reductions will depend on rainfall events and canola N utilization.

Environmental Effects on the Relative Competitive Ability of Canola and Small-Grain Cereals in a Direct-Seeded System

Growing crops that exhibit a high level of competition with weeds increases opportunities to practice integrated weed management and reduce herbicide inputs. The recent development and market dominance of hybrid canola cultivars provides an opportunity to reassess the relative competitive ability of canola cultivars with small-grain cereals. Direct-seeded (no-till) experiments were conducted at five western Canada locations from 2006 to 2008 to compare the competitive ability of canola cultivars vs. small-grain cereals. The relative competitive ability of the species and cultivars was determined by assessing monocot and dicot weed biomass at different times throughout the growing season as well as oat (simulated weed) seed production. Under most conditions, but especially under warm and relatively dry environments, barley cultivars had the greatest relative competitive ability. Rye and triticale were also highly competitive species under most environmental conditions. Canada Prairie Spring Red wheat and Canada Western Red Spring wheat cultivars usually were the least competitive cereal crops, but there were exceptions in some environments. Canola hybrids were more competitive than open-pollinated canola cultivars. More importantly, under cool, low growing degree day conditions, canola hybrids were as competitive as barley, especially with dicot weeds. Under most conditions, hybrid canola growers on the Canadian Prairies are well advised to avoid the additional selection pressure inherent with a second in-crop herbicide application. Combining competitive cultivars of any species with optimal agronomic practices that facilitate crop health will enhance cropping system sustainability and allow growers to extend the life of their valuable herbicide tools.

Canola Response to ESN and Urea in a Four‐Year No‐Till Cropping System

Nitrogen fertilizer is a major input cost in canola (Brassica napus L.) production and farmers are interested in improving N use efficiencies. A multi‐site study in western Canada was conducted to determine the merits of polymer‐coated urea (Environmentally Smart Nitrogen, ESN) compared with urea on weed management and yield of hybrid and open‐pollinated (OP) canola. Treatments included a hybrid and OP canola cultivar, ESN and urea, 100 and 150% of soil test N fertilizer rates, and 50 and 100% of registered in‐crop herbicide rates. Canola was grown in rotation with barley (Hordeum vulgare L.) in a no‐till system and both crops of the rotation were present each year. Fertilizer and herbicide rate treatments were applied to the same plots in four consecutive years to determine annual and cumulative effects. Hybrid compared with OP canola reduced weed tissue N concentration in 40% of the cases and reduced weed biomass in 80% of the cases. Additionally, weed tissue N concentration was lower with ESN than with urea in 70% of the cases, indicating that crop–weed competition for soil N might be reduced if ESN were used. Canola yield was greater for the hybrid cultivar in 15 of 20 site‐years. Both cultivars expressed a positive yield response to the 150% N fertilizer rate in 10 of 20 site‐years. This yield response occurred in three additional site‐years with hybrid canola, indicating that hybrid cultivars have a higher N demand under favorable growing conditions. Canola yield was similar with ESN and urea in 14 of 20 site‐years. The ESN compared with urea increased canola yield in 4 site‐years and in one additional site‐year for hybrid canola, indicating that ESN may be advantageous in some situations. Canola seed oil concentration was similar with ESN and urea in 19 of 20 site‐years. Information gained in this study will be used to develop improved fertilization strategies for canola production on the semiarid Canadian prairies.

Fertilizer response for hybrid and open-pollinated canola and economic optimal nutrient levels

Hybrid (HY) canola (Brassica napus L.) produces a higher seed yield than open-pollinated (OP) canola. While it is expected higher-yielding HY canola may require higher total available nutrients, especially nitrogen (N), the evidence is not conclusive. This study used canola yield data from several site-years and fertility experiments to determine whether HY and OP canola types require different rates of total available N (TAN) and total available phosphorus (TAP). The yield response of the two canola genotypes to TAP was the same, but for TAN the yield response was greater for HY canola. The quadratic yield response results were confirmed using three plateau equations. Optimal TAN for HY canola was higher than for OP canola. Soil test laboratories and producers growing HY canola need to modify N fertility for HY canola, compared with OP canola for which most of the current N fertilizer recommendations were developed. Key words: Economics, fertilizer, yield response, canola, hybrid, open-pollinated

Fertilizer N response and canola yield in the semiarid Canadian prairies

Canola is a viable crop when grown under fallow in the semiarid prairie, but is also grown in longer rotations, most often no-till seeded into standing stubble. Selecting the proper N fertilizer rate is a very challenging production decision, but most of the available nitrogen response for canola has been derived for the more subhumid parts of the Canadian prairies. We developed simple quadratic equations to describe the yield relationship for stubble-seeded open-pollinated and hybrid canola in the semiarid Canadian prairie. These relationships indicate that hybrid canola produced higher grain yields at all fertilizer rates and had optimum N fertilizer rates about 50% higher than those for open-pollinated canola. Key words: Canola, fertilizer N, grain yield, water use, semiarid prairie

Productivity and quality of canola and mustard cultivars under weed competition

Competitive crops or cultivars can be an important component of integrated weed management systems. A study was conducted from 2003 to 2006 at four sites across semiarid prairie ecoregions in Saskatchewan and Alberta to investigate the productivity and quality of canola (Brassica napusL.) and mustard cultivars under weed competition. Four open-pollinated canola cultivars, four hybrid canola cultivars, two canola-quality mustard and two oriental mustard cultivars [Brassica juncea (L.) Czern. & Coss.], and two yellow mustard (Sinapis alba L.) cultivars were grown under weedy and weed-free conditions. When combined across site-years, crop aboveground biomass at maturity and seed yield were reduced by weed interference, except for yellow and oriental mustard. However, seed oil and protein content of cultivars were not affected by weed competition. Among crop types, yellow and oriental mustard were best able to maintain biomass and seed yield under weed interference, followed in decreasing order of competitiveness by hybrid and open-pollinated canola, then canola-quality mustard. Key words: Brassica napus, Brassica juncea, Sinapis alba, weed competition

Weed Suppression by Canola and Mustard Cultivars

Competitive crops or cultivars can be an important component of integrated weed management systems. A study was conducted from 2003 to 2006 at four sites across semiarid prairie ecoregions in western Canada to investigate the weed-suppression ability of canola and mustard cultivars. Four open-pollinated canola cultivars, four hybrid canola cultivars, two canola-quality mustard cultivars, two oriental mustard cultivars, and two yellow mustard cultivars were grown in competition with indigenous weed communities. Yellow mustard was best able to suppress weed growth, followed in decreasing order of weed competitiveness by oriental mustard and hybrid canola, open-pollinated canola, and canola-quality mustard. Competitive response of cultivars, assessed by weed biomass suppression, was negatively correlated with time to crop emergence and positively correlated with early-season crop biomass accumulation (prior to bolting) and plant height.Nomenclature: Canola, Brassica napus L., oriental mustard or canola-quality mustard, Brassica juncea L. Czern. & Coss., yellow mustard, Sinapis alba L

Comparative nitrogen response and economic evaluation for optimum yield of hybrid and open-pollinated canola

Plant breeders have dramatically improved the yield potential of new canola cultivars. To achieve optimum yield with such cultivars, particularly hybrids, may require changes to fertilizer management practices that were established prior to development of these cultivars. We investigated the influence of N fertilizer rate (0, 30, 60, 90, 120, and 150 kg N ha-1) on plant density, days to flowering, length of flowering stage, days to maturity, biomass, seed yield and quality, and economic returns of two canola cultivars (Quantum, a high-yielding open-pollinated; and InVigor® 2663, a high-yielding hybrid) on a Dark Brown (Scott), a Thick Black (Melfort), and a Thin Black (Indian Head) Chernozem soil in Saskatchewan in 2000 and 2001. Plant density was slightly lower for InVigor 2663 than Quantum due to larger seed size of the former. InVigor 2663 tended to take more days to flowering and had shorter flowering stage duration compared with Quantum, but the two cultivars showed no consistent difference for the number of days to maturity. InVigor 2663 generally produced more biomass and seed yield than Quantum. Oil and protein concentration in seed were higher for InVigor 2663 than Quantum, with an opposite trend for the proportion of green seeds, indicating better seed quality for InVigor 2663. Addition of N tended to reduce plant density and decreased seed oil concentration, while it increased crop growth duration, seed protein concentration, seed yield and biomass. Under adequate N fertilization, InVigor 2663 provided greater net economic returns than Quantum under both moist and relatively dry conditions. In conclusion, InVigor 2663 performed better agronomically than Quantum, but the similar nature of seed yield response to applied N suggests that target N fertilizer rates for optimum seed yield and net economic returns should be similar for both cultivars based on this limited comparison of one hybrid and one open-pollinated canola cultivar under these soil-climatic conditions. Key words: Brassica napus L., hybrid canola, N rate, open-pollinated canola, seed quality, seed yield

Economic evaluation of seeding decisions in hybrid and open-pollinated herbicide-resistant canola (Brassica napus)

Herbicide-resistant canola (Brassica napus) is widely cultivated in western Canada. Data from a multi-year field experiment conducted at three locations in Alberta were used to investigate the effect of canola cultivar, time of seeding, polymer seed coating (PSC) on profitability and the net return risk. Cultivars included hybrid and open pollinated. Time of seeding was early and late fall, and early and normal spring. The hybrid canola generally had higher mean net return than the open-pollinated cultivar. The probability of thin canola stand was higher for fall dormant seeding compared with spring seeding. The use of PSC for early fall dormant seeding reduced the likelihood of thin canola stand, which translated into risk-efficient decision. However, PSC use for late fall seeding had mixed results. Early and normal spring seeding was generally risk-efficient at all locations. In exceptional cases, net returns from late fall dormant seeding (with or without PSC) were similar to that of spring seeding. Re-seeding of fall seeded canola in the spring could be beneficial, if the plant density was below 20 plant m-2. Seeding decisions were robust across a wide range of canola prices, based on the probability of negative net returns. Key words: Canola, fall seeding, net returns, polymer seed coat, re-seeding, risk

Response of four canola populations to ethametsulfuron

Abstract The effect of ethametsulfuron on populations of canola was evaluated in field and laboratory trials. Three canola populations (TR4, CB9604, and BC86-18) and the open-pollinated canola cv. ‘AC Parkland’ were treated with several doses of ethametsulfuron at the two- to four-leaf stage. In the field experiment, plant densities were determined before spraying and again at plant maturity. Density reductions during the growing season were observed for all populations (6 to 17%), but reductions due to ethametsulfuron above 0.3 g ha−1 depended on year, being noted for TR4 in 1997 (40 to 65%) only. In laboratory trials, only TR4 demonstrated sensitivity to ethametsulfuron, up to 49% visual damage averaged over all plants. The response was binary, with about 40% of plants at any given herbicide rate surviving unharmed and the remaining 60% of plants exhibiting > 90% visual damage. It is concluded that TR4 is sensitive to ethametsulfuron and further work, including a comprehensive genetic study, is required...