Rapeseed

Lore & Background

Rapeseed (Brassica napus subsp. Its bright yellow flowers are about 17 mm across, radial, with four petals in a cross-form alternating with four sepals. The flowers have indeterminate racemose flowering, starting at the lowest bud and growing upward. The pods are green, elongated siliquae that ripen to brown, growing on pedicels 1–3 cm long and ranging 5–10 cm in length. Each pod has two compartments separated by an inner wall, containing round seeds 1.5–3 mm in diameter, black and hard at maturity with a reticulate surface. The species Brassica napus belongs to the Brassicaceae family. Rapeseed is a subspecies with the autonym B. napus subsp. napus, encompassing winter and spring oilseed, vegetable, and fodder rape. Siberian kale is a distinct leaf rape form variety (B. napus var. pabularia). The second subspecies is B. napus subsp. rapifera (rutabaga, swede, or yellow turnip). B. napus is a digenomic amphidiploid from hybridization between B. oleracea and B. rapa, and is self-compatible. The term 'rape' derives from the Latin word for turnip, rāpa or rāpum. Rapeseed is a relatively recent crop in human history; Brassica napus itself is a hybrid that originated in Europe or the Mediterranean region, not among the earliest cultivated plants like wheat or barley. Brassica napus was introduced to China much later, likely around the 13th–14th century CE. Winter rapeseed is predominantly grown in Europe and Asia, requiring vernalization, while spring rapeseed is cultivated in Canada, northern Europe, and Australia. It is primarily insect-pollinated (especially by bees), with wind playing a minor role, and shows significantly increased yields when bee-pollinated. Rapeseed has a high demand for nutrients, especially sulfur, and requires attention to boron, manganese, and molybdenum.

Reader's Guide

Rapeseed is a globally significant crop, ranking as the third-largest source of vegetable oil and the second-largest source of protein meal. The crop faces challenges from climate change, which is expected to reduce its cultivatable range and yield quality. Diseases such as canker, light leaf spot, and blackleg, along with pests like the brassica pod midge and cabbage seed weevil, require management through fungicides and insecticides. Genetic research, including SNP arrays and SLAF-seq, has advanced breeding efforts. The crop's high sulfur demand and sensitivity to micronutrients like boron and manganese shape cultivation practices. Its legacy lies in its dual role as a source of edible oil and protein, with ongoing adaptation to environmental and agricultural pressures.

Did You Know?

• Rapeseed is the third-largest source of vegetable oil and the second-largest source of protein meal in the world.
• The plant is primarily insect-pollinated (especially by bees), with wind playing a minor role, but bee pollination can almost double the final yield, depending on the cultivar.