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Péron, J.-Y. 1990. Seakale: A New Vegetable Produced as Etiolated Sprouts. p. 419-422. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR.

Seakale: A New Vegetable Produced as Etiolated Sprouts*

Jean-Yves Péron

  1. INTRODUCTION
  2. THE PLANT AND ITS AGRICULTURAL HISTORY
  3. FOOD VALUE AND USE
    1. Nutritional Composition
    2. Culinary Uses
  4. CULTURAL SYSTEM FOR SEAKALE IN NORTHERN FRANCE
    1. Cutting Production Phase
    2. Field Production Phase
    3. Etiolated Sprouting Phase in Dark Chamber
  5. PROSPECTS
  6. REFERENCES
  7. Table 1
  8. Fig. 1

INTRODUCTION

Etiolation of vegetables (Bois 1927, Péron 1986a, b) modifies various organoleptic properties such as reduction in fiber and bitter or aromatic substances. Generally, the edible portions of plants subjected to etiolaltion are foliated rosettes or young stalks of biennials or perennials. The etiolation phenomenon takes place more often at the beginning of spring after rest. Transfer of plants to a dark chamber and the application of a temperature level near the optimum for plant growth, permit the production of etiolated portions, at the beginning of winter.

Witloof chicory (Cichorium intybus L), white asparagus (Asparagus officinalis L), cardoon (Cynara cardunculus L.) and dandelion (Taraxacum officinale Weber ex Wigg.) are the best known etiolated vegetables. Other less common vegetables, such as rhubarb (Rheum spp.) (Norman 1985), skirett (Sium sisarum L.) (Péron 1989a), and seakale (Crambe maritima L.) (Péron 1989b) could be produced by this method. This paper describes the culture system we propose for the economic resurgence of seakale.

THE PLANT AND ITS AGRICULTURAL HISTORY

Seakale is a member of the Brassicaceae, tribe Cakilineae. It is a perennial wild plant of the north-west European coast and the Black Sea region (Scott and Randall 1976). Morphologically seakale looks like large foliated cabbage. The first leaves are purple and successive leaves become greener. Mature leaves are usually over 30 cm long (and can reach more than 90 cm), long stalked, more or less pinnately lobed with wavy margins. When the plant is fully grown, it develops 0.8-1.5 cm large white flowers highly visited by bees and , then, 0.75-1.0 cm diameter light silques. These indehiscent fruits usually contain one seed. Roots are cylindrical and vigorous and show a capacity for regeneration when divided. Root cutting is the most efficient propagation method for seakale.

Seakale is a fully cross-pollinated plant and is self-incompatible (Bourdelet 1986). Genetic variability is large and involves such economic characters as morphology of vegetative and reproductive organs, earliness, and anthocyanin formation in the leaves.

Under the climatic conditions of northern France, the development cycle of seakale is similar to rhubarb. Sprouts of early spring growth are etiolated and white if they develop without light as in witloof chicory and asparagus. Etiolated sprouts are the only edible portion of seakale (Péron 1986b).

Seakale had been cultivated in England during the end of the 19th Century and the beginning of the 20th. Today except for few gatherers living in wild seakale area, this food plant is virtually unknown to consumers.

FOOD VALUE AND USE

Nutritional Composition

Nutritional composition of seakale was first reported by Randoin (1937). A complete nutritional analysis has been carried out in our institute based on the forcing method described in this paper (see Table 1).

Culinary Uses

Etiolated sprouts can be eaten either raw or boiled like asparagus (4 minute boiling time). The flavor of young rosettes resembles that of cabbage with a fine hazel taste.

Peeling is unnecessary before boiling, making seakale a ready-to-eat vegetable. It can be served alone as white asparagus or served with shellfish, fish, or meat. The best chefs of Angers (M. Bignon, J.F. Piers, and M. Sabourault, unpublished) consider seakale as a modern vegetable with good potential.

CULTURAL SYSTEM FOR SEAKALE IN NORTHERN FRANCE

The cultural system used for modern witloof chicory production is proposed for seakale. The clone C.C.o, obtained in 1984 from a root cutting of a selection in our botanical garden has been used to devise this cultural system which consists of three parts (Fig. 1).

Cutting Production Phase

In vitro plantlets and root cuttings are adapted for field setting. Micropropagation permits rapid plantlet production (Péron and Régnier 1987) but, because of high cost, is used only for initial rapid increase of new clones.

Shoot regeneration capacity is high in root cuttings. Cuttings come from plants before their transfer in dark chamber. They are kept at low temperature and high atmospheric humidity until field setting in spring.

Field Production Phase

Field setting takes place between March 15 and May 15. The optimal date is the end of March for root cutting and the beginning of May for in vitro plantlets. Optimal planting density approaches 54,000 plants per hectare.

The duration of growth in the field is about 6-8 months during which time the plants form one or several foliar rosettes. Growth stops and the leaves abscise about November 15. At this time, the plants could be transferred into a dark chamber. Seakale plants can be partially killed by frost at -15°C to -18°C. The yield per hectare of field production is similar to asparagus.

Etiolated Sprouting Phase in Dark Chamber

After removing a part of the root biomass, the plants are set in a peat moss substrate and transferred in dark forcing chamber at 15°C and 85% relative humidity. The etiolated sprouts are edible after 28-30 days.

The market window for the edible sprouts is between December 20 and March 15. The yield per plant varies from 30 to 120g depending on the level of root biomass of the forcing plant and the time it enters the forcing chamber.

PROSPECTS

Commercial production has been carried out in several parts of the north of France since 1988 after preliminary experimental trials in Brittany (1985) and the Loire Valley (1987). The cultivar used is a clone obtained in 1984 from a plant in our botanical garden, propagated by root cutting. This clone and its propagation method are protected by French patent (8401984) and U.S. patent (4645031).

Because of its food value, seakale could be an attractive vegetable in the future. However, much research needs to be conducted in production (plant breeding, physiological and agronomic studies) and marketing (product positioning and packaging). Like every new crop, the success of seakale will depend on a partnership strategy between the grower, researcher, and marketer.

REFERENCES

*Program of seakale studies has been helped in finances by French Ministry of agriculture and by ANVAR. I am grateful to Andrée Le Boulch and M. Ouvrard for technical assistance and M. Théron for agronomic studies. Thanks to Martine Gouget and M. Declercq for their collaboration in nutritional analysis of seakale.
Table 1. Nutritional composition of raw etiolated sprouts of seakale produced in the dark.

Components Quantity per 100 g
of fresh matter
Dry matter (g) 6.9
Protein (g) 2.10
Caloric value (kcal) 16.9
Soluble fibers (g) 0.8
Insoluble fibers (g) 0.8
Sulphur (mg) 28.0
Potassium (mg) 430.0
Nitrates (mg) 17.0
Thiamine (mg) 0.27
Folic acid (mg) 0.099
Valine (mg) 0.072
Histidine (mg) 0.034
Tryptophane (mg) 0.047

Fig. 1. The different phases of seakale cultivation.

Propagation (a) 5-week-old root cutting (8-10 cm length) obtained from excessive root biomass before transferring to dark.
(b) In vitro plantlet, cultured on basal Murashige-Skoog (MS) medium with 6.0 mg/liter kinetin and 1.5 mg/liter benzyladenine; root formation on MS medium with 1.0 mg/liter a-naphthaleneacetic acid; 9 weeks required for root formation and acclimatization.
Field production phase. (c) Field growth of seakale in the summer under 200 N, 39 P, 208 K (kg/ha); with black polyethylene mulch and pest management similar to that of cabbage.
Etiolated sprout phase in dark chamber. (d) Roots prepared for sprout production,
(e) general view during sprout production 150-250 roots per m2;
(f) edible etiolated sprouts on 4 weeks old forcing plant obtained from root cutting.

Last update September 4, 1997 by aw