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Rapp, K., S.K. Næss, and H.J. Swartz. 1993. Commercialization of the cloudberry (Rubus chamaemorus L.) in Norway. p. 524-526. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New York.

Commercialization of the Cloudberry (Rubus chamaemorus L.) in Norway

Kåre Rapp, S. Kristine Næss, and Harry Jan Swartz

  1. PLANT DESCRIPTION
    1. Distribution
    2. Morphology
  2. COMMERCIALIZATION PROSPECTS
    1. Progress
  3. REFERENCES
  4. Fig. 1
The cloudberry, Rubus chamaemorus L., Rosaceae, is a small herbaceous bramble common to peat bogs in the northern hemisphere (Fig. 1). The berry has a strong musky flavor, quite distinct from that of any of the other bramble crops, and is highly prized as a dessert berry in Scandinavia. Recently, demand for the development of the cloudberry as a commercially viable crop has increased in northern Norway where many districts are struggling to maintain a viable economy.

PLANT DESCRIPTION

Distribution

The cloudberry is a circumpolar, subarctic species. It can be found as far north as 78°30' N in Svalbard, Norway and its distribution extends south to 44°N in New Hampshire, U.S.A. (Resvoll 1929). It is a common plant in northern Norway, and is also found in the highland areas and mountains farther south.

Morphology

The cloudberry is a dioecious perennial herb. The plant spreads mainly by means of an extensive rhizome system. Annual shoots consisting of from one to four lobed leaves may terminate in a single staminate or pistillate flower. Insect pollination is required for fruit set to occur in most places though wind pollination may also contribute to fruit set in coastal windswept areas.

In Norway, the cloudberry begins ripening in the end of July or early August. The berry, resembling a large amber raspberry, consists of from 5 to 25 drupelets. The cloudberry contains from 50 to over 150 mg ascorbic acid per 100 g fruit (Nordness and Werenskiold 1951; Heller 1981). It is also rich in benzoic acid (Honkanen and Pyysalo 1976) and can therefore be easily stored for several weeks or longer under normal refrigeration. For these reasons the cloudberry was favored in the prevention of scurvy by Norwegian sailors and North American Eskimos (Faegri 1970; Heller 1981).

COMMERCIALIZATION PROSPECTS

Although the cloudberry is a common plant throughout northern Norway, the Norwegians are unable to satisfy their domestic demand for the berry. In some years, 200 to 300 tons of cloudberries are imported from Finland. The cloudberry harvest in the wild is highly unpredictable due to the unstable weather conditions prevailing in the beginning of June when the cloudberry flowers. Early frost in August may also destroy the crop in some years. In general, cloudberry yields from bog plants are very low, only averaging about 20 kg/ha. Domestication of the cloudberry would not only help fill the market demand for the berry but would also provide an attractive crop for use in boggy areas where little else of agricultural value can be grown. Several growers organizations have now been formed in Norway and a consultant has been employed at Holt Research Station, Tromsø, Norway (69°29'N) to study the commercialization potential of the crop and set forth research priorities.

Progress

Bog management. A number of bog management practices have been developed which can lead to greatly increased yields. Plowing furrows into a bog with a spacing of from 1 to 5 m leads to an increase in cloudberry proliferation and can reduce the incidence of spring freezes (Lid et al. 1961; Østgard 1964; Makinen and Oikarinen 1974; Rapp 1982). Fertilization of the bog with superphosphates or complete fertilizers (300 kg/ha) can increase yields per hectare by an average of 50 kg when the fertilizer is placed at a depth of 20 to 25 cm (Rapp 1989). Fertilizers applied to the surface of the bog or at greater depths tend to benefit other bog species at the expense of the cloudberry. In windswept areas, short fences may be useful in settling the snow in the winter to delay the blossoming period and therefore avoid spring frost injury. The use of windrows also leads to an increase in the activity of pollinating insects and has increased yields (Østgard 1964).

Genotype improvement. A prerequisite for the success of any of these bog management practices is the existence of a good stand of pistillate (fruit bearing) plants. In most cloudberry producing bogs, less than 25% of the flowering shoots are pistillate (Lid et al. 1967). Even among seedling populations there is an overabundance of male plants (Rapp 1987). Current research is aimed at the breeding of higher yielding pistillate or hermaphrodite cultivars and the development of efficient propagation methods.

The development of cloudberry cultivars is well underway at the Holt Research Station in northern Norway. Hundreds of seedlings from several different environments have been screened for high flower production and large berry size (Rapp 1988). Further performance evaluations have been made on promising selections in square meter plots where their ability to spread and become rapidly established can also be assessed. From these, two superior pistillate clones (An 267 and If 542), and two superior staminate clones (An 30 and An 257), have now been selected for cultivar release.

The development of hermaphrodite cultivars is an important goal in the domestication of the cloudberry. Occasionally, hermaphrodite flowers can be found in the wild. Several plants bearing such flowers have been collected for evaluation. Unfortunately, sex expression in these plants varies from year to year and also from flower to flower within a clone. Plants with hermaphroditic tendencies are currently being used as parents in the cloudberry breeding program in an attempt to develop stable hermaphrodite cloudberry cultivars.

Several crosses between cloudberry and other Rubus species including a hybrid blackberry, red raspberry clones, and several Asiatic ideobats have produced plants with overall general chamaemorus morphology (thornless, herbaceous, non-elongating) however, leaf pattern is definitely hybrid. The blackberry x cloudberry cross is much more vigorous than other hybrids and cloudberries.

Rapid and good seed germination is important to the success of a cloudberry breeding program. Normally cloudberry seed require 6 to 8 months cold stratification before germinating and germination rates are often well below 50% (Rantala 1976). By removing the endocarp and seed coat from fresh cloudberry seed, we have obtained in vitro germination rates of 75 to 85% four weeks after culture initiation.

Plant propagation. The cloudberry is difficult to propagate relative to other bramble species. Large turfs must be dug when collecting selections from the wild to ensure transplant survival. Further propagation of the selection can be made through the use of rhizome cuttings. The success rate with rhizome cuttings has been greatly improved by increasing the length of the cutting from about 7 cm to 15 to 20 cm. The best results have been obtained when the rhizome cuttings are taken in May or August (Rapp 1986). Although the cloudberry proliferates readily in tissue culture, explant rooting remains a major problem.

REFERENCES

Fig. 1. The cloudberry.
Last update September 15, 1997 aw