Rapeseed

• 1. Introduction

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  Rapeseed fields flower bright yellow, yet the seed inside naturally carries a mildly toxic compound called erucic acid. The plant goes by several names, including rape, oilseed rape and canola. It ranks as the third-largest source of vegetable oil in the world. It is also the second-largest source of protein meal. A crop with that kind of chemistry should have stayed a curiosity. Instead it spread across continents and into kitchens, barns and fuel tanks. This documentary asks how a plant with a toxic edge became so widely grown, and what breeders had to change along the way. It asks what the name canola really marks. It follows a dispute between a seed company and farmers that ended in a courtroom. And it asks what else a rapeseed field can yield besides oil.

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• 2. Anatomy and Kin

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  Brassica napus grows to about 100 cm tall, and its leaves tell you a lot. The lower ones are hairless, fleshy, lobed and waxy, and they sit on stalks. The upper leaves have no stalks at all.

  Each bright yellow flower measures roughly 17 mm across. It has four petals in the typical cross shape, alternating with four sepals. Flowering is indeterminate, so it begins at the lowest bud and climbs upward over the following days. Inside, two lateral stamens have short filaments. Four median stamens have longer ones, and their anthers split away from the center of the flower.

  The fruit is a long pod called a siliqua. It is green while developing and turns brown as it ripens. A central wall divides each pod into two compartments, and a row of round seeds grows in them. At maturity the seeds are black and hard, with a net-like surface.

  Telling rapeseed from its relatives takes a careful look. Brassica nigra has upper leaves that clasp the stem, while rapeseed does not. Brassica rapa has larger petals, whereas rapeseed petals measure less than 13 mm across.

  Rapeseed belongs to the flowering plant family Brassicaceae. Its full name is Brassica napus subsp. napus, a group that takes in winter and spring oilseed, vegetable and fodder rape. Siberian kale, a leaf rape form, used to be a common winter-annual vegetable. The second subspecies, rapifera, is the rutabaga, also known as the swede or yellow turnip.

  Genetically, Brassica napus is a digenomic amphidiploid. It arose when two other species, Brassica oleracea and Brassica rapa, hybridized. Like other amphidiploid Brassicas, it can pollinate itself. Even the word rape has a plain origin. It comes from the Latin word for turnip, rāpa or rāpum, which is cognate with the Greek ῥάφη, rhaphe.

  In Northern Ireland, naturalists record Brassica napus and Brassica rapa as escapes growing on roadside verges and waste ground.

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• 3. Fields and Seasons

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  Roughly 10,000 years ago, crops from the genus Brassica were already among the earliest plants that people cultivated widely. Rapeseed itself was grown in India as early as 4000 BCE. It spread to China and Japan 2000 years ago.

  In most of Europe and Asia, farmers plant the winter form, because it needs vernalization before it can begin to flower. The seed goes in during autumn. Through winter the plant stays as a leaf rosette on the soil surface. The next spring it sends up a long vertical stem, followed by lateral branches. Flowering usually comes in late spring. Pods then develop and ripen over 6-8 weeks, until midsummer.

  In Europe, winter rapeseed works as an annual break crop in rotations of three to four years. It alternates with cereals such as wheat and barley, and with other break crops such as peas and beans. The rotation limits how many pests and diseases carry over from one crop to the next. Winter rape is more vigorous than the summer variety, so it can make up for pest damage and is less likely to fail.

  Canada, northern Europe and Australia grow the spring form instead. It is not winter-hardy and needs no vernalization. Sown in spring, it starts stem development immediately after germination.

  Rapeseed grows on a wide range of well-drained soils and prefers a pH between 5.5 and 8.3. It has a moderate tolerance of salty soil. The wind carries most of its pollen, yet bees can almost double the final grain yield. That effect depends on the cultivar.

  Modern crops get heavy doses of nitrogen-containing fertilizer. An estimated 3-5% of that nitrogen is converted into N2O, a gas released as a by-product of making the fertilizer.

  The crop is also hungry for other nutrients. Its sulphur demand is the highest among all arable crops. Boron, manganese and molybdenum are the micronutrients that growers must watch most closely.

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• 4. Pests and Genetics

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  Wood pigeons and slugs are on the list of rapeseed's enemies, along with a wide variety of insects and nematodes. In Europe the primary insect pests are the brassica pod midge, the cabbage seed weevil, the cabbage stem weevil, the cabbage stem flea beetle, the rape stem weevil and pollen beetles. Some feed on developing pods, lay eggs inside, and let the young eat the growing seeds. Others bore into stems or feed on pollen, leaves and flowers.

  Synthetic pyrethroid insecticides are the main weapon against these insects. Many countries also use prophylactic insecticides on a large scale. Against slugs, growers spread molluscicide pellets before or after sowing.

  The main diseases of winter rapeseed are canker, light leaf spot caused by Pyrenopeziza brassicae, and alternaria and sclerotinia stem rots. Canker spots the leaves and weakens the stem. It also ripens the crop prematurely during the autumn-winter period. A conazole or triazole fungicide goes on in late autumn and again in spring against canker. Broad-spectrum fungicides cover alternaria and sclerotinia in spring and summer. Soil-borne diseases such as sclerotinia, verticillium wilt and clubroot mean oilseed rape cannot be planted in close rotation with itself.

  Blackleg, caused by Leptosphaeria maculans, also called Phoma lingam, is a major disease. In 2005, Yu and colleagues used restriction fragment length polymorphism analysis on two doubled haploid populations, DHP95 and DHP96. They found resistance genes, including one called LepR1.

  Genetic engineering offers another route. In 2012, Chhikara and colleagues combined a barley chitinase with a ribosome inactivating protein in a related species, Brassica juncea. The pairing cut hyphal growth by 44% in Alternaria brassicicola and delayed disease presentation.

  In 2009, Bayer Cropscience announced it had sequenced the entire genome of Brassica napus, together with the genomes of its parents, Brassica rapa and Brassica oleracea. Partners included BGI-Shenzhen in China, KeyGene in the Netherlands and the University of Queensland in Australia. The Multinational Brassica Genome Project had separately sequenced the A genome component.

  Breeders have since gained sharper tools. Dalton-Morgan and colleagues released an SNP array for the species in 2014, and Clarke and colleagues released another in 2016. Both are now widely used in molecular breeding. In 2016, Geng and colleagues applied specific locus amplified fragment sequencing to the crop. It revealed the genetics of its past domestication and helped build a high-density linkage map.

  Epigenetics matters too. In 2009, Hauben and colleagues found that isogenic lines did not use energy equally well in real growing conditions, because of epigenetic differences.

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• 5. Making Canola

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  In the 1970s, rapeseed oil could contain up to 54% erucic acid. That acid damages the cardiac muscle of animals. High glucosinolates also made the meal less nutritious as animal feed. Although rapeseed oil is one of the oldest known vegetable oils, these problems kept its historical use limited.

  In 1973, Canadian agricultural scientists launched a marketing campaign to encourage people to eat canola. Seed, oil and meal from cultivars low in both erucic acid and glucosinolates were then registered as a trademark in 1978. The owner was the Canola Council of Canada, and the name was canola. Today canola is a generic term for edible rapeseed varieties. Canada still defines it officially as oil with less than 2% erucic acid, from a meal with less than 30 μmol of glucosinolates per gram of air-dried, oil-free meal.

  Oil from these cultivars is also called low-erucic-acid rapeseed oil, or LEAR oil. The United States Food and Drug Administration has generally recognized it as safe. Regulations cap erucic acid at 2% by weight in both the US and the EU, with special rules for infant food. Such low levels are not believed to harm human infants.

  Breeding for low glucosinolates had an unexpected side effect in the 1980s. Atmospheric sulphur inputs to Northern European soils were falling. The new low-glucosinolate varieties, called 00-varieties, also used sulphur less efficiently inside the plant. White flowering, a highly specific symptom of sulphur deficiency, appeared more often. Officials running the variety assessment procedures wrongly blamed it on genetic inhomogeneity and nicknamed it "Canadian blood".

  Wild animals raised a similar false alarm. Damage from animals foraging on 00-oilseed rape was expected. It turned out to come from a shift in their diet toward more protein and sulphur-containing metabolites, at the expense of fibers. It did not come from any special feature of the 00-varieties.

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• 6. Roundup Ready Dispute

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  In 1998, Monsanto brought a genetically engineered rapeseed to the Canadian market. It was built to withstand the company's herbicide, Roundup. Tolerance to glyphosate made it widely regarded as the most disease- and drought-resistant canola. By 2009-90% of the rapeseed planted in Canada was of this kind.

  Monsanto sought compensation from farmers whose fields held the cultivar without a paid license fee. Those farmers answered that pollen carrying the Roundup Ready gene had blown into their fields and crossed with unaltered canola. Other farmers told a different story. They sprayed Roundup on non-canola fields to kill weeds before planting. Roundup Ready volunteers survived the spraying, and clearing them cost extra.

  The Supreme Court of Canada settled the best-known case in 2004, in Monsanto Canada Inc. v. Schmeiser. It found for Monsanto on its patent infringement claim over unlicensed growing of Roundup Ready. Yet it also ruled that Schmeiser did not have to pay any damages. Many saw the decision as a court-sanctioned legitimization of global patent protection for genetically modified crops, and it drew international controversy.

  The story ended quietly in March 2008. An out-of-court settlement committed Monsanto to clean up the entire GMO-canola crop on Schmeiser's farm. The cost was about CAN$660.

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• 7. Oil, Meal and Fuel

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  The Food and Agriculture Organization reports that global production reached 36 million tonnes in the 2003-2004 season. Its estimate for 2010-2011 was 58.4 million tonnes. By 2021, the world total in the source's production table stood at 72 million tonnes. Worldwide production of rapeseed, canola included, grew sixfold between 1975 and 2007. That rise opened up the edible oil market to rapeseed oil.

  Crushing the seed for oil leaves behind rapeseed meal. This high-protein animal feed competes with soybean, and it goes mostly to cattle, with some for pigs and poultry. Rapeseed also makes excellent silage, which is fermented and stored airtight as winter feed. But glucosinolates, sinapine and phytic acid in the seed cake have costs. They harm animal health, reduce the digestibility of certain nutrients and make the feed less palatable. They also add to eutrophication of waterways. In China, the meal goes mostly onto soil as fertilizer.

  A European policy change in 2003 pushed rapeseed toward the fuel tank. The European Parliament's Transport Biofuels Directive promoted biofuels, and winter rapeseed cultivation in Europe increased dramatically. Since 2002, biodiesel production in the EU and US has risen steadily, reaching 6 million tonnes in 2006.

  Rapeseed oil can serve as biodiesel, burn straight in heated fuel systems, or be blended with petroleum distillates. Biodiesel can run pure in newer engines without damage. It is often mixed with fossil-fuel diesel at 2-20% biodiesel. Growing, crushing and refining make biodiesel from new oil costlier than standard diesel, so diesel fuels are commonly made from used oil instead.

  In most of Europe, rapeseed oil is the preferred feedstock, at about 80% of the total. It yields more oil per unit of land than sources such as soybeans. The main reason, though, is that canola oil has a significantly lower gel point than most other vegetable oils.

  Climate change clouds this picture. The cultivatable range for rapeseed is expected to shrink, and both yield and oil volume are expected to fall substantially. A 2018 study predicted that rapeseed would become an unreliable source of oil for biofuels. Some researchers recommend finding alternative Brassica varieties to grow.

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• 8. Unexpected Harvests

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  Rapeseed honey is whitish or milky yellow, with a peppery taste. Rapeseed has a high melliferous potential, meaning it produces substances that insects can collect, and it is a main forage crop for honeybees. The honey crystallizes within 3-4 weeks and can ferment if stored improperly. Its low fructose-to-glucose ratio makes it granulate quickly in the comb. That forces beekeepers to extract it within 24 hours of the honeycomb being capped.

  In the United States, rapeseed grown over winter works as a cover crop. It prevents soil erosion, produces large amounts of biomass and suppresses weeds. Its root system can improve soil tilth. Some cultivars are grown as annual forage, ready for grazing livestock 80-90 days after planting.

  In Austria, a biolubricant with 70% or more canola or rapeseed oil has replaced petroleum-based chainsaw oil. It typically costs more. As a biolubricant, rapeseed also has possible biomedical uses, such as lubricants for artificial joints.

  Worked into the soil, rapeseed meal acts as a biofumigant. It suppresses fungal crop pathogens such as Rhizoctonia solani.

  The oddest job came after the Chernobyl disaster. Researchers studied rapeseed as a way to contain radionuclides that had contaminated the soil, because its uptake rate is up to three times that of other grains. Only about 3-6% of the radionuclides it absorbs end up in the oilseeds.

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