Canola In Australia Research Articles

Optimal Contribution Selection Improves the Rate of Genetic Gain in Grain Yield and Yield Stability in Spring Canola in Australia and Canada.

Crop breeding must achieve higher rates of genetic gain in grain yield (GY) and yield stability to meet future food demands in a changing climate. Optimal contributions selection (OCS) based on an index of key economic traits should increase the rate of genetic gain while minimising population inbreeding. Here we apply OCS in a global spring oilseed rape (canola) breeding program during three cycles of S0,1 family selection in 2016, 2018, and 2020, with several field trials per cycle in Australia and Canada. Economic weights in the index promoted high GY, seed oil, protein in meal, and Phoma stem canker (blackleg) disease resistance while maintaining plant height, flowering time, oleic acid, and seed size and decreasing glucosinolate content. After factor analytic modelling of the genotype-by-environment interaction for the additive effects, the linear rate of genetic gain in GY across cycles was 0.059 or 0.087 t ha-1 y-1 (2.9% or 4.3% y-1) based on genotype scores for the first factor (f1) expressed in trait units or average predicted breeding values across environments, respectively. Both GY and yield stability, defined as the root-mean-square deviation from the regression line associated with f1, were predicted to improve in the next cycle with a low achieved mean parental coancestry (0.087). These methods achieved rapid genetic gain in GY and other traits and are predicted to improve yield stability across global spring canola environments.

Impact of Fungicide Application and Host Genotype on Susceptibility of Brassica napus to Sclerotinia Stem Rot across the South-Western Australian Grain Belt: A Genotype × Environment × Management Study

Sclerotinia stem rot (SSR), caused by the necrotroph Sclerotinia sclerotiorum Lib. (de Bary), is a major disease of canola in Australia, greatly reducing yields in high infection years. This study investigated genotype by environment by management interactions at 25 sites across the south-west Australian grainbelt from 2017 to 2020. Up to 10 canola varieties were grown each year with +/− fungicide application at 30% flowering. Disease incidence was low, with less than 20% infection recorded across most sites. Most variation in yield occurred between sites, rather than by management or variety, due to the environmental differences between the sites. Petal assays were found to be a poor indicator of later disease severity, suggesting the winter growing season in south-west Australia does not have reliable conducive conditions for disease development following petal drop in canola. The Additive Main Effects and Multiplicative Interaction model (AMMI) indicated that the open-pollinated varieties were broadly adapted and stable when fungicide was applied but became unstable with no fungicide, indicating SSR has a significant impact on yield when disease incidence is higher. This study highlights that further research is necessary to determine disease thresholds that lead to significant yield loss.

Defining optimal sowing and flowering periods for canola in Australia

Increasingly variable rainfall and temperatures and larger farm size in Australia have prompted earlier sowing of canola (Brassica napus L.). Improved agronomy and the release of cultivars suited to a wider range of environments have facilitated the expansion of canola production into new environments. To maximise grain yield at earlier sowing dates and in new environments, growers need to know the most suitable development pattern for their environment and sowing date to reduce production losses associated with frost, heat and drought at flowering. A simulation analysis was conducted at 77 locations across the Australian cropping zone to determine the optimal period for flowering to start in order to maximise long-term yield. The simulation accounted for effects of frost, heat and water stress on yield as well as duration of biomass accumulation. The optimal start of flowering period (OSF) was a function of the environment rather than the cultivar, and the relative importance of frost, heat and water stress varied with location. We found that the OSF was earlier (mid to late July), in most Mediterranean environments of Western Australia, South Australia and Victoria and later (August to September) in the southern temperate environments of Tasmania, Victoria and New South Wales (NSW). In medium and low rainfall areas of NSW, temperature extremes and rainfall interacted so that the OSF occurred in mid-July to mid-August. In low rainfall environments the duration of the optimal period was shorter (19–35 days) in most cases than in high rainfall environments (30–52 days). Knowledge of the OSF for a location, will allow breeders to develop cultivars with appropriate phenological characteristics for target environments. For growers, an understanding of the OSF, combined with an appropriate phenology classification of commercial cultivars, will allow selection of cultivar and sowing date combinations which decrease the risk of stress and maximise productivity.

The economic and environmental cost of delayed GM crop adoption: The case of Australia's GM canola moratorium

ABSTRACTIncorporating socio-economic considerations (SECs) into national biosafety regulations regarding genetically modified (GM) crops have opportunity costs. Australia approved the cultivation of GM canola through a science-based risk assessment in 2003, but allowed state moratoria to be instituted based on potential trade impacts over the period 2004 to 2008 and 2010 in the main canola growing states. This analysis constructs a counterfactual assessment using Canadian GM canola adoption data to create an S-Curve of adoption in Australia to measure the environmental and economic opportunity costs of Australia's SEC-based moratoria between 2004 and 2014. The environmental impacts are measured through the amount of chemical active ingredients applied during pest management, the Environmental Impact Quotient indicator, and greenhouse gas emissions. The economic impacts are measured through the variable costs of the weed control programs, yield and the contribution margin. The environmental opportunity costs from delaying the adoption of GM canola in Australia include an additional 6.5 million kilograms of active ingredients applied to canola land; a 14.3% increase in environmental impact to farmers, consumers and the ecology; 8.7 million litres of diesel fuel burned; and an additional 24.2 million kilograms of greenhouse gas (GHG) and compound emissions released. The economic opportunity costs of the SEC-based moratoria resulted in foregone output of 1.1 million metric tonnes of canola and a net economic loss to canola farmers' of AU$485.6 million. The paper provides some of the first quantified, post-adoption evidence on the opportunity cost and environmental impacts of incorporating SECs into GM crop regulation.

Fungal diseases of canola in Australia: identification of trends, threats and potential therapies

Fungal diseases are the major constraint on canola (Brassica napus) production in Australia and worldwide. Blackleg (caused by Leptosphaeria maculans) and Sclerotinia stem rot (Sclerotinia sclerotiorum) are the predominant diseases limiting production but, with increased intensification of production, other diseases previously considered of minor importance and sporadic may be increasing in prevalence. We report on the incidence and severity of four ‘minor’ diseases of canola in Australia: white leaf spot (caused by Pseudocercosporella capsellae), downy mildew (Peronospora parasitica), Alternaria leaf and pod spot (Alternaria brassicae) and powdery mildew (Erysiphe cruciferarum). Diseases were monitored at more than 30 sites across Australia from 2013 to 2015. Regions were identified in which specific diseases are a consistent problem, such as white leaf spot in Hamilton in Victoria. In these regions, control strategies to minimise disease may be required. Varietal differences were observed for some diseases suggesting that resistance to these pathogens is already present in Australian advanced breeding material. Lastly, fungicide applications were shown to control some diseases such as white leaf spot.

Blackleg disease of canola in Australia

Blackleg disease caused by the fungus Leptosphaeria maculans is the most important disease of canola worldwide. The impact of this disease on the development of the Australian canola industry, particularly over the last 20 years, is discussed. Deployment of a range of disease control measures has resulted in a thriving canola industry with production now approaching 4 million tonnes annually. Discoveries about disease mechanisms and key plant and fungal genes are described. Analysis of the L. maculans genome sequence has enabled an understanding of how fungal populations can evolve rapidly to overcome disease resistance bred into canola cultivars.

Biological control of sclerotinia stem rot of canola using antagonistic bacteria

Stem rot caused by Sclerotinia sclerotiorum is a major fungal disease of canola worldwide. In Australia the management of stem rot relies primarily on strategic application of synthetic fungicides. In an attempt to find alternative strategies for the management of the disease, 514 naturally occurring bacterial isolates were screened for antagonism to S. sclerotiorum. Antifungal activity against mycelial growth of the fungus was exhibited by three isolates of bacteria. The bacteria were identified as Bacillus cereus (SC‐1 and P‐1) and Bacillus subtilis (W‐67) via 16S rRNA sequencing. In vitro antagonism assays using these isolates resulted in significant inhibition of mycelial elongation and complete inhibition of sclerotial germination by both non‐volatile and volatile metabolites. The antagonistic strains caused a significant reduction in the viability of sclerotia when tested in a greenhouse pot trial with soil collected from the field. Spray treatments of bacterial strains reduced disease incidence and yielded higher control efficacy both on inoculated cotyledons and stems. Application of SC‐1 and W‐67 in the field at 10% flowering stage (growth stage 4·00) of canola demonstrated that control efficacy of SC‐1 was significantly higher in all three trials (over 2 years) when sprayed twice at 7‐day intervals. The greatest control of disease was observed with the fungicide Prosaro® 420SC or with two applications of SC‐1. The results demonstrated that, in the light of environmental concerns and increasing cost of fungicides, B. cereus SC‐1 may have potential as a biological control agent of sclerotinia stem rot of canola in Australia.

Integrating dual-purpose wheat and canola into high-rainfall livestock systems in south-eastern Australia. 1. Crop forage and grain yield

The development of guidelines for successful dual-purpose (graze and grain) use of wheat and canola in Australia’s high-rainfall zones (HRZ) has mostly emerged from separate wheat- and canola-focused research. Less attention has been placed on the benefits of integrating dual-purpose wheat and canola into pasture-based grazing enterprises. We conducted a farming systems experiment during 2010–11 to evaluate the benefits of integrating wheat and canola as dual-purpose crops into a pasture-based grazing system in Australia’s south-eastern tablelands. We compared forage production and grain yield in three separate crop–livestock systems in which the sheep grazed long-season wheat, winter canola or a combination of these. Initial growth rates were higher in early-autumn-sown canola than wheat in 2010, but were much lower although similar in both crops in 2011. Significant forage was available from both canola (3.1–3.4 t ha–1) and wheat (2.3–2.4 t ha–1) at the onset of grazing, but winter growth rates of wheat were higher than those of canola, leading to increased sheep grazing days (SGD). In the favourable 2010 season, dual-purpose wheat and canola separately provided 2393 and 2095 SGD ha–1, and yielded 5.0 and 1.9 t ha–1 grain, respectively, with an apparent nitrogen limitation in canola. In the drier season of 2011, grazing was reduced to 1455 and 735 SGD ha–1 in wheat and canola, respectively. Wheat yield was reduced from 5.9 to 5.4 t ha–1 grain by grazing, whereas canola yield was unaffected (3.6 t ha–1). In both years, grazing did not affect harvest index or oil content of canola, but harvest index was higher in grazed wheat crops. The yield of wheat and canola crops grazed in sequence did not differ from yield in treatments where animals grazed only a single crop, but the total overall grazing window when crops were grazed sequentially increased by 1054 and 618 SGD ha–1 in wheat, and by 1352 and 1338 SGD ha–1 in canola in 2010 and 2011, respectively. The major benefits of including crops that can be grazed sequentially were the widening of the grazing window and other operational windows (sowing, harvest), along with the rotational benefits for wheat by including canola in the system. Additional benefits to pastures may include eliminating the need to re-sow, because a more productive pasture composition is maintained under lower grazing pressure while stock are on crops, and reduced weed invasion. The commercial availability of new, herbicide-tolerant winter canola varieties provides significant opportunities to underpin the performance of dual-purpose crop sequences on mixed farms in the high-rainfall zone.

Breakdown of resistance to the fungal disease, blackleg, is averted in commercial canola (Brassica napus) crops in Australia

The fungus Leptosphaeria maculans causes blackleg disease of canola (Brassica napus). This fungus has a high evolutionary potential, and extensive sowing of a cultivar in a region can lead to blackleg resistance bred into the cultivar becoming ineffective within 3 years. Monitoring of disease severity and virulence of fungal populations across canola-growing regions of Australia in 2011 revealed a high risk of breakdown of resistance of cultivar Hyola50 on the lower Eyre Peninsula, South Australia, but not elsewhere. Cultivar Hyola50 has two resistance genes, based on the pattern of segregation of resistance in the plant and avirulence in the fungus. One of these is Rlm1, a gene that was rendered ineffective previously in commercial crops of canola in Australia and France. Acreage sown to Hyola50-related cultivars decreased dramatically in 2012 after release of a warning to farmers in this region not to sow these cultivars. At a field trial in this region, disease severity in 2012 in cv. Hyola50 was 85%, while that of cultivars containing different resistance genes was much lower. By not sowing cv. Hyola50, farmers in an area of about 60,000ha on the lower Eyre Peninsula, saved AU$ 13 million in predicted yield losses.

First Report of Club Root Caused by Plasmodiophora brassicae on Canola in Australia.

In 2009, a disease survey was conducted in 97 commercial canola (Brassica napus L.) fields in Western Australia by the Department of Agriculture and Food, Western Australia (DAFWA). In about 20% of the fields from the northern agricultural region of Western Australia, small patches were observed where canola plants showed symptoms of stunting and wilting. These plants were collected and roots of affected plants were washed thoroughly and examined for the presence of root disease. Small galls and clublike structures were observed on the secondary roots and sometimes on the main root of the affected plants. Examination of thin free hand sections from the root galls revealed that several cortical cells were enlarged and full of resting spores. The diameter of resting spores ranged between 2.5 and 3.0 μm. Plasmodia and zoosporangia were also observed in the root hairs. The identity of Plasmodiophora brassicae Woronin was confirmed by PCR using a modified method of Cao et al. 2007 (1). DNA from spores and slices of the galls of 14 different samples were extracted using DNeasy plant mini kit (QIAGEN Australia) as per manufacturer's instructions. Samples were disrupted by placing them into MPBIO tube A and placed in the Fast Prep machine at speed of 6 ms-1 for 40 s. This was repeated twice. The species-specific primers TC1F (5'-GTGGTCGAACTTCATTAAATTTGGGCTCTT-3')/TC1R (5'-TTCACCTACGGAACGTATATGTGCATGTGA-3') and TC2F (5'-AAACAACGAGTCAGCTTGAATGCTAGTGTG-3')/TC2R (5'-CTTTAGTTGTGTTTCGGCTAGGATGGTTCG-3') were used (1). The primers TC1F and TC1R failed to produce a PCR product of 548-bp size but using the primers TC2F and TC2R the PCR reaction resulted in a 519- bp fragment. Seven out of 14 samples gave positive results for P. brassicae with primers TC2F and TC2R. This indicates that the P. brassicae pathotype from Western Australia may be different than the one found in Alberta, Canada. However, pathotypes of P. brassicae from brassica vegetables from Australia have been found similar to the populations of P. brassicae present in the United States (2). Pathogenicity of P. brassicae was tested by dipping roots of five 10-day-old canola plants var. Cobbler in a spore suspension (1 × 106 resting spores/ml). Roots of five control plants were dipped in sterile water. Five weeks after inoculation, small galls were observed on the roots of three inoculated plants and the control plants remained symptomless. Resting spores were recovered from the galls developed on the roots of affected plants. Presence of P. brassicae in the affected roots was further confirmed by PCR using the method described above. To our knowledge, this is the first report of club root of canola in Australia. Club root is reported from vegetable brassicas and white mustard (Sinapis alba L.) in Australia. Club root has become a serious disease of canola in Canada since its detection in Alberta in 2006 (3). The resting spores of the fungus can survive for several years in soil, and therefore, this disease could pose a significant threat to canola production in Western Australia.

The Controversy over GM Canola in Australia as an Ontological Politics

In this paper I examine the controversy over genetically modified canola (GM canola) in Australia as an ontological politics, drawing on recent work in Science and Technology Studies that extends actor-network theory and its commitment to the contingency of reality. I examine three different and overlapping performances of GM canola: as an agronomic object, a risk object and a market object. I focus on how each performance effects similarities and differences between GM and conventional canola that are productive of ontological distinctions that make GM canola controversial. I argue this analysis offers useful insights that are not revealed by more traditional explanations of controversy.

Anti‐Nutritional Components, Fibre, Sinapine and Glucosinolate Content, in Australian Canola (Brassica napus L.) Meal

AbstractCanola meal is highly regarded as a component of animal feed with a high protein content and a desirable amino acid profile. The presence of some components, in particular glucosinolates, sinapine and fibre, affects the value of the meal and reduces the amount that can be used in animal feed formulations. Glucosinolates in traditional cultivars (rapeseed) had very high amounts and this severely limited the usefulness of the meal. Canola breeding programs have successfully reduced glucosinolate content to trace amounts. However sinapine remains at levels sufficiently high to cause problems, particularly in poultry feed. The relatively high fibre level in canola also reduces the value of the product for animal feed. This study has determined the level of sinapine, glucosinolates and fibre in current cultivars of canola in Australia to illustrate advances made by breeding programs and limitations which still remain to raise the usefulness of a potentially valuable feedstock. Although glucosinolate levels in meal were shown to have been reduced to 11 μmol/g in some cases, sinapine remained at traditional levels of about 12–15 g/kg and neutral detergent fibre levels were about 30–40%. These issues are important priorities for canola breeders.

New root diseases of canola in Australia

Macrophomina phaseolina, Fusarium acuminatum and F. semitectum are recorded as pathogens of canola in Australia for the first time. These fungi attack the roots of seedling and adult canola in south-eastern Australia.

Symptoms of blackleg (Leptosphaeria maculans) on the roots of canola in Australia

The fungus Leptosphaeria maculans (anamorph Phoma lingam) causes blackleg in canola (Brassica napus). Infection of all above-ground parts of the plant has been described, but there are no reports of infection of roots. In a recent review West et al. (1999) described the common plant symptoms, but did not mention root infection. Canola plants at the flowering and pod-filling stages, with foliar symptoms of blackleg, were collected from commercial crops in South Australia, Victoria and New South Wales, Australia in November and December 2000. Some plants had lodged and had the basal cankers commonly described for blackleg, however, many plants had died prematurely during late pod fill. Cankers and other external symptoms were not present on the lower stems of these plants and many could be pulled easily from the ground. The lateral roots had blackened areas. Taproots had extensive internal tissue necrosis. In some plants, the pith of the stem was also necrotic, although there were no external symptoms. In another case, a distinct black band was seen around the circumference of the taproot below the crown. Samples of discoloured tissue were surface-sterilized and cultured on quarter-strength potato dextrose agar. Phoma lingam was isolated from all samples, identified as described by Punithalingham & Holliday (1972). All isolates were virulent (A-group) according to PCR-based tests carried out by the Root Disease Testing Service, South Australian Research and Development Institute (Sosnowski et al., 2001). Phytophthora and Rhizoctonia spp. were not isolated from the discoloured tissues. Pycnidiospore suspensions (106 spores mL−1) were prepared from two isolates of P. lingam (66/97 and 208/00) obtained from leaves and roots, respectively, of diseased plants. These suspensions were used to inoculate (i) lateral roots severed with surface-sterilized scissors; and (ii) hypocotyls wounded with sterile toothpicks on otherwise healthy canola seedlings in the glasshouse. Three weeks after inoculation, stem and crown cankers appeared on plants inoculated with either isolate on either roots or hypocotyls and root tissue was necrotic, whereas control plants, wounded as described above and inoculated with sterile water, remained healthy. Phoma lingam was the only pathogen isolated from diseased root tissue. This confirms the occurrence of the blackleg fungus in the roots of canola plants, and reveals its ability to infect through wounds in the roots. This is the first record of symptoms of blackleg on canola roots in Australia. However, there is anecdotal evidence that such symptoms have occurred in the past (D. Ballinger, Dovuro Pty Ltd, Horsham, Victoria, Australia, personal communication; M. Barbetti, Agriculture Western Australia, South Perth, Western Australia, Australia, personal communication). Initially it was assumed that the infection had spread from the crown into the roots, but new evidence suggests that the disease can also be soilborne. This may have important ramifications for understanding the blackleg disease cycle. This aspect will be investigated further in the current project entitled ‘Investigating resistance and management of blackleg in canola’, which is funded by the Australian Research Council, the South Australian Grains Industry Trust Fund and the South Australian Research and Development Institute.

Characterization and Pathogenicity of Rhizoctonia Species on Canola.

A total of 112 Rhizoctonia isolates were collected from various canola (Brassica napus) growing areas of Western Australia. Pectic enzyme electrophoresis differentiated these isolates into six distinct zymogram groups: R. solani, 54% ZG5 (AG2-1), 8% ZG6 (AG2-1), and 1% ZG9 (AG10); binucleate Rhizoctonia, 12% CZG1 (CAG1), 4% CZG4, and 6% CZG5 (AGK); and the remainder unidentified binucleate groups (15%). Binucleate groups were also confirmed by fluorescent nuclear staining and hyphal morphology. One or more isolates from each of the above zymogram groups (including four unidentified binucleate groups) and an isolate of ZG1-1 (AG8) that causes bare patch in cereals and legumes were tested for their pathogenicity on canola. Isolates of ZG5 and ZG1-1 were highly pathogenic on canola, delayed seedling emergence, and caused severe hypocotyl and root rot, respectively. ZG5 also induced postemergence damping-off. Increasing the depth of sowing from 1 to 3 cm significantly delayed seedling emergence and increased disease severity. Four unidentified binucleate isolates (WAC9316, WAC9297, WAC9307, and WAC9290) were moderately pathogenic to canola, while two isolates (WAC9307 and WAC9316) caused significant preemergence damping-off. Two CZG5 isolates were weakly pathogenic. Isolates of ZG5 and ZG1-1 were also tested for their pathogenicity on other rotational crops (narrow-leafed lupin, subterranean clover, wheat, oats, barley, and mustard) and two weed species (wild radish and annual ryegrass). ZG5 caused a severe hypocotyl rot on mustard and mild symptoms of hypocotyl rot on narrow-leafed lupin and clover, but failed to infect any of the cereal hosts, such as wheat, oats, barley, and ryegrass. In contrast, all crops tested were highly susceptible to ZG1-1 except mustard, which was only moderately susceptible. Results indicate that ZG5 is most pathogenic to crucifers and is a mildly virulent pathogen of the leguminous crops but not of cereal crops tested. ZG1-1, known to cause bare patch in legumes and cereals, also can cause severe root rot in canola. This is the first report of hypocotyl rot and pathogenicity of ZG5 on canola in Australia.

Reducing height and lodging in rapeseed with growth regulators

The plant growth regulators (PGRs) ethrel (20% a.i. 2-chloroethane phosphonic acid), PP 333 (25% w/v a.i. paclobutrazol), cycocel (50% w/v a.i. chlormequat chloride), pix (5% w/v a.i. mepiquat chloride) and EL 500 (50% w/w a.i. flurprimidol) were applied to bulky crops of Jumbuck, Marnoo and RU 14 rapeseed at Cowra and Woodstock in central-western New South Wales, in an effort to reduce their height and lodging. The most effective growth retardants under evaluation were PP 333 and EL 500, and this was achieved without apparent phytotoxicity. Height reductions were enhanced as rates were increased from 0 to 2 Lha, and the heights of Jumbuck, Mamoo and RU 14 were reduced on average by 22% (from 159 to 124 cm), 26% (from 136 to 100 cm) and 14% (from 150 to 129 cm), respectively. Significant reductions in lodging accompanied these changes. Ethrel resulted in some phytotoxicity, while pix and cycocel had little or no measured effect on any plant characters. Jumbuck was the tallest variety and the most severely lodged, and under these conditions, yield responses to PGR were large (900 kg/ha or 54%). Shorter, erect plants produced an even, compact pod canopy, and as a result, ripening was more uniform, pod shattering reduced and harvesting more efficient. In situations where seed yields were increased, these practical considerations, rather than physiological responses (e.g. pod and seed set), were largely responsible. These findings support further research and commercial development of PGRs for use in canola production in the more favoured areas and support the inclusion of reduced plant height and increased stem strength as integral components of the overall breeding objectives for canola in Australia.