Crops Amaranth

Summary Information



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Seeds

The tiny seeds, naturally dark but usually light-coloured in cultivated types, are richer in protein, oil, and minerals than cereal grains. The leaves and young shoots may be used as a green vegetable or fodder crop, and some kinds are grown specifically for these purposes in many parts of Africa and Asia. Amaranth has been developed in the USA as a protein rich grain for popping or flour production, used in products such as breakfast and snack foods: production is increasing and some is now being used in European food industries. More recently it has been discovered that the seeds contain very fine starch granules with distinctive properties which make them suitable for use in cosmetics and biodegradable plastics, while the oil fraction includes substances which are also useful in cosmetic manufacture and in the control of vascular cholesterol levels. Some initial agronomic investigation has been conducted in the UK and in France.

Young plants, from above

Young plant, from side

Amaranths are strongly-growing herbaceous annuals, which develop rapidly in warm conditions. The root may grow to 2 m or more while top growth may attain 3 m in height, though this depends on species, crop density, and growing conditions. The main stem grows stiffly erect with variable amounts of branching, the short-stemmed leaves being of a pointed oval shape with prominent veining.

Developing flower-heads

The flower- heads are conspicuous, complex structures consisting of large numbers of separate stems, erect or drooping, each bearing many small petal-less flowers. Foliage or flower-heads may be coloured pink or deep red, as in the plants which are cultivated for display purposes.

Fully grown flower-heads

A well-worked soil is essential; shallow sowing and some form of soil pressing is also required to ensure rapid germination of the fine seeds. For mechanised cultivation it is suggested that an established population of 30 plants per square metre is desirable, which may be achieved at seed rates as low as 0.5 kg per ha if a suitable precision seeder is available. No herbicides have yet been proved to be safe, so early weed control is by mechanical methods, the crop later being sufficiently vigorous to shade out weeds. Nitrogen fertiliser at a rate of 125 kg per ha is recommended. When dry the crop may be cut by combine harvester, but desiccation (or a killing frost) may be necessary to reduce plant moisture levels first. Seed yields of 2 t per ha should be obtainable: up to 4 t per ha has been recorded at Sonning in some years.

Amaranths are plants of warm areas, tolerant of some degree of soil salinity as well as drought: they are probably not best-suited to culture in the more northerly parts of Europe due to lack of frost- resistance, which shortens the potential growing season at both ends. Cropping for starch or oil content alone seems unlikely to be economically viable at present, but could provide additional income if the crop were to be grown for the production of edible protein.