Prota 2: Vegetables/Légumes
2n = 22
Parsnip (En). Panais (Fr). Pastinaga (Po).
Origin and geographic distribution
Parsnip is native to Europe and temperate Asia. It is cultivated mainly in temperate regions worldwide and only occasionally in cooler parts of the tropics, including East and southern Africa. It is mainly grown in home gardens and for specialty markets. It was already a popular crop during Roman times and one can still find a wide diversity in Moroccan and Algerian markets.
The fleshy, aromatic and slightly mucilaginous root is eaten as a cooked or fried vegetable. It is also used in soups and to add flavour to stews. It is especially popular in the United Kingdom. The seed, which tastes similar to dill, is occasionally used as a condiment. The leaves have diuretic properties. A poultice from the roots has been applied to sores and inflammations, and to treat skin diseases.
The nutritional composition of parsnip root per 100 g edible portion is: water 79.5 g, energy 3140 kJ (750 kcal), protein 1.2 g, fat 0.3 g, carbohydrate 18.0 g, fibre 4.9 g, Ca 362 mg, P 71 mg, Fe 0.6 mg, Mg 29 mg, Zn 0.6 mg, vitamin A absent, thiamin 0.09 mg, riboflavin 0.05 mg, niacin 0.70 mg, folate 67 μg, ascorbic acid 17.0 mg (USDA, 2002).
All parts of parsnip contain essential oil. The essential oil from the fully-grown root is rich in myristicin and terpinolene and contains small amounts of (E)-β-farnesene, β-bisabolene, β -sesquiphellandrene and γ-palmitolactone. Furanocoumarins are present in the plant; these compounds may cause contact dermatitis. Parsnip contains minute amounts of the steroid 5α-androst-16-en-3-one or boar-pheromone which contributes to its characteristic fragrance.
Glabrous to slightly hairy biennial herb up to 150 cm tall, with fusiform, fleshy white taproot; stem erect, hollow, grooved. Leaves alternate, pinnate, without stipules; petiole sheathed at base; leaflets sessile, ovate-oblong, often with some lobes at base, 2–13 cm × 1–5 cm, toothed. Inflorescence a terminal, compound umbel with unequal rays; involucral bracts 0–2, deciduous. Flowers bisexual, but male flowers present in addition to bisexual flowers, c. 2 mm in diameter, 5-merous; petals yellow; ovary inferior, 2-celled. Fruit a flattened ellipsoid schizocarp 5–7 mm long, ribbed, slightly winged. Seedling with epigeal germination; hypocotyl 0.5–1.5 cm long, epicotyl absent; cotyledons stalked, ovate-lanceolate, herbaceous.
Parsnip is a slow -growing, deep-rooted plant. The flowers are pollinated by insects. Parsnip is self-fertile.
Parsnip is a cool season crop. Optimum temperature for growth is 15–18°C. Roots produced under warm conditions do not have the strong and distinctive flavour of those grown under cooler conditions. Parsnip is biennial and requires vernalization for flower induction. It can grow in slightly shady localities (open woodland) or in full sunlight. In the tropics it can only be cultivated above 900 m altitude. The root is tolerant of hard frost. Under the influence of low temperatures starch in the root is converted to sugars. Parsnip requires a deep, light to medium -textured soil with good drainage. In clay soils germination and root growth are poor.
Parsnip seed is sown in situ, thinly in rows 40–50 cm apart at a spacing of 1–2 cm in the row and covered with about 1 cm of fine soil. The weight of 1000 seeds is about 3.5 g. Seed is difficult to preserve and often has a low germination rate. Germination is best at 19–24°C, but still takes about 2 weeks. In a soil that has a capping tendency, a light irrigation just prior to germination helps seedlings to emerge. In home gardens parsnip seed is sometimes mixed with radish seed. The quick growing radish breaks the soil crust and can be harvested before it starts competing with the parsnip plants. Plants are thinned after 4–5 weeks to a spacing of 10–12 cm. Slight earthing-up after thinning is recommended. Parsnip needs careful weeding as early growth is slow. The application of a compound fertilizer (8–14–10) at a rate of 500–700 kg/ha at planting is recommended, if necessary topdressed with 20 kg N after 4–6 weeks. Fresh manure should be avoided as it causes plants to become hairy and branched. Parsnip prefers a constantly moist soil. Erratic irrigation may cause roots to crack or become fibrous. Parsnip does not suffer much from pests or diseases. To avoid white mould (Sclerotinia sp.) and root-knot nematodes parsnip should be grown in a wide crop rotation. Alternaria leaf blight, powdery mildew (Erisiphe umbelliferarum) and Cercospora leaf blight may occur and may need control by fungicides. Leaf blight and powdery mildew are favoured by warm humid weather; improved aeration may reduce their incidence. Cutworms may cause some damage.
Parsnip roots are ready for harvesting after 90–150 days. In temperate areas they are often left until after the first frost as their sweetness increases under low temperatures. They can not be pulled up and have to be uprooted by careful digging. A yield of 25 t/ha is considered good. Once parsnip roots have been harvested they lose water quickly. They can be stored in soil clamps or under refrigeration at 0°C and relative humidity of at least 90%.
Genetic resources and breeding
The old cultivar ‘Hollow Crown’ is mostly cultivated in East Africa; other well-known cultivars are ‘Guernsey’ and ‘Offenham’, both with shorter roots. No breeding programmes are known to exist. The North Central Regional PI Station, Ames, Iowa, United States maintains a small collection of Pastinaca germplasm.
In tropical Africa parsnip is likely to remain a vegetable of minor importance, mainly for consumers of European origin.
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Correct citation of this article:
Oyen, L.P.A., 2004. Pastinaca sativa L. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.