Class: Magnoliopsida (dicotyledons)
Origin and diffusion
The Amaranthus genus includes about 60 species, some of which are divided according to use.
Flowers of Amaranthus hypocondriacus (photo http://b-and-t-world-seeds.com)
It is an annual herbaceous plant of variable height according to the species from 0.5 to 3.5 m with leaves of different shapes, from oval to lanceolate. The flowers are grouped in inflorescences (panicles) that can be erect or hanging, branched, up to 90-100 cm long, typical red (due to the content of beta-cyanins), green or yellowish.
The seeds are small in size, flattened in a circular shape, varying in color from very light to milk-white, to yellow-gold, or from brown to black.
They measure about 1-1.5 mm in diameter and the weight of 1,000 seeds is between 0.5-0.6 and 1 g.
Amaranthus cruentus seeds - Amaranth plant
In the areas of origin, Mexico and Central America, amaranth is also grown at an altitude of up to about 2,800 m asl, mainly using A. caudatus and A. hypocondriacus. In other areas with a temperate climate, A. cruentus is the species on which a cultivation technique has been developed, suitable for industrial agriculture, although still to be perfected in some of its aspects.
In our environments amaranth is a typical spring-summer crop that can be inserted in rotations with cereals, legumes and vegetables.
In consideration of the small size of the seed, the preparation of the seed bed takes on particular importance for the success of the crop, which is why it requires fairly loose soils and with a pH between 6 and 7.5.
The most used sowing technique is that in rows 50-60 cm apart; you can proceed in a continuous line (10-12 kg / ha of seed) or resort to precision sowing (3-5 kg / ha) with a highly variable density according to the architecture of the variety used; from 20 to 60 plants / m2.
According to the fertility of the soil and the cultural precession, it is good practice to distribute a fertilization in pre-sowing with a ratio of 1: 2: 0.5 between nitrogen, phosphorus and potassium, considering as a base about 50-80 kg / ha of the first element.
When the plants have reached a height of about 20-25 cm, weeding is carried out which sometimes must be repeated together with a tamping, especially if the plants are very tall with long and hanging panicles.
The cycle of the species varies between 100 and 160 days after sowing.
Collection, production and use
Maturation is scaled and harvesting is the most delicate phase of the whole agronomic technique.
In fact, the ripe seeds detach easily from the panicle, causing loss of a certain consistency, especially if it proceeds with mechanical harvesting, even if small differences have been observed according to the variety used.
In order to minimize seed losses, it will be necessary to reach a compromise between the humidity and humidity of the panicle or, in the same way as for other species, to cut the plants and, after drying, proceed to threshing. A character that must be sought in the varieties to be subjected to mechanized harvesting is the "dry down", that is to say the partial fall of the leaves in conjunction with the maturation of the seed.
In fact, in the varieties that or for a long time the fresh parts, the seed falls early and, considering them to be minute dimensions, remains attached to the leaves and is lost.
The rediscovery of this plant as a precious food resource dates back to the seventies, when some studies launched by Dowton (1973) highlighted its remarkable nutritional properties of the most common species: Amaranthus cruentus L., A. hypocondriacus L., A. caudatus L. and A. edulisspeg.
In the United States, China and India, amaranth is grown on large areas and is now considered on a par with other industrial crops (Tucker, 1986; Granado and Lòpez, 1990).
The main characteristics of this species, of which, in addition to the seeds, you can also consume the leaves like a spinach, are the high content of proteins (15-18%), of lysine and of calcium respectively with averages of 5, 2 and 0.37 g / 100 g of dry matter (Petr et al., 2003), as well as being characterized by the absence of gluten and therefore suitable for the nutrition of celiacs (Ballabio et al., 2011). In particular, the lysine content, higher than some foods of vegetable (cereals, beans, soy) and animal (meat, milk, eggs) origins, gives this species high market potential especially where, up to now, it has been almost exclusively confined to the health sector (Hackman and Myers, 2003).
Amaranth is used for the formulation of bars, snacks, muesli, puffed seeds, extrusions and other products such as biscuits and bread. For this latter use, however, and in general for the production of leavened pasta, mixing with cereal flours is necessary which in the case of products for celiacs can be corn, sorghum, rice or millet.
Amaranth flour does not contain simple sugars and this, given the high content of amylopectin and complex sugars, allows its use in the diets of obese and diabetics.
A particular use of this species is that of amaranth milk which, due to its excellent balance of amino acids and the high calcium content, is indicated for the feeding of children, the elderly and lactose intolerant (Teutonic and Dietrich, 1985).
The leaves of some particularly pigmented varieties can be used for the extraction of a red dye used in the food industry.
The cosmetic and pharmacological sector benefits from amaranth above all by the high content of squalene in the oil, an average 4.6% fatty acid content.
Amaranth oil, contained in seeds for an average of 6.0%, with its content of tocopherols, compounds generally indicated as vitamin E, together with squalene, are used in the cosmetic industry especially in the skin care sector and hair.
Another particular use is that of the use of starch characterized by very small granules that can be used as a base for non-allergenic aerosols and also as a substitute for talc in cosmetics.
Adversity and pests
Paolo Casini - Felice La Rocca
Department of plant, soil and agro-forestry production sciences University of Florence