Ocimum basilicum L.
Lamiaceae (sin. Labiatae)
History and Origins
It has spread from the Middle East in Ancient Greece and in Italy since the days of Alexander the Great around 350 BC. Only in the XVI century was it cultivated in England and, with the first migratory expeditions, in the Americas.The name derives from the Medieval Latin basilicum, originating from the greek basilikon (phyton) (“royal, majestic plant”), from basileus (king). Of uncertain etymology, some interpretations claim it was named as such for its use in producing fragrances for the king, or possibly in reference to its sacred use by the ancient Hindu populations, or more simply, for the “royal” importance given to the plant.The name may have been confused with that of the Basilisk, the creature from Greek mythology described as a lethally poisonous snake that had the power to kill with just a look, and basil was said to be the antidote.
As a medicinal plant, the leaves and flowering tops are used to prepare infusions with different effects: sedative,
antispasmodic for the digestive tract, stomachic (which promotes appetite), diuretic, antimicrobial and anti-inflammatory infusions. Basil is also used against indigestion and as a vermifuge; as a mouthwash, it is recommended for the prevention of inflammation of the oral cavity.
The essential oil is used for massaging areas of the body that are in pain or affected by rheumatism.
The antiviral, antimicrobial and anti-inflammatory properties of basil is mainly due to its content of rosmarinic acid
(antioxidant phenolic compounds).
Diffusion and importance
Root: taproot system, a rather superficial but highly ramified root system.
Stem: erect, quadrangular, branching stems reaching a height of up to 50 cm.
Leaves: Opposite, oblong, glossy or rumpled, green or purple colour, containing an essential oil with a characteristic aroma, a short stalk.
Flower: whitish, gathered in groups of 6-10 on an elongated spike; fertilization is crossed (allogamous species) with predominantly entomophilous pollination. Flowering takes place from June to October.
Fruit: achene (tetrachene), ovoid, shiny, blackish, small (1.3-1.5 g/1000 seeds).
Basil has high thermal requirements (see table). While it grows well in direct sunlight, slightly shady conditions favour the formation of tender leaves with a delicate aroma. It has high water requirements.
Basil prefers light or medium soils, free draining (no stagnant water), rich in organic matter, with a pH of 7.
It is a typical crop of the spring-summer cycle that should not be replanted in the same soil for at least another three
Varieties and/or commercial types
Species and subspecies used commercially for consumption and the extraction of essential oils can be divided as
O. basilicum L. maximum L.: common sweet basil with large and smooth leaves. The best-known cultivars are the Genovese, the most renowned in Italy – a DOP (denomination of a protected origin) product – whose scent is, compared to other types of basil, particularly delicate and completely devoid of the fragrance of mint.
O. basilicum L. minimum L.: reduced height, small and very aromatic leaves – the best-known varieties: Fine Verde, Dwarf, Greek Bush basil .
O. basilicum L. bullatum L.: rumpled leaves – Variety: Lettuce Leaf, Neopolitan.
O. basilicum L. thyrsiflorum (L.) Benth.: Thai basil, the aroma of its leaves reminiscent of mint and clove; it is used with seafood and exotic soups.
O. basilicum L. purpurascens Benth.: pigmented purple-leaved varieties (eg. cv. Purple Ruffles, Purple Mexican Basil).
O. basilicum L. citriodorum: Several varieties including those with a lemon fragrance.
O. gratissimum L.: Also known as Clove or African Basil, height of up to 3 m, used for the extraction of its essential oil, with a very pleasant aroma and high phenol content (thymol, eugenol), native to India and Africa.
O. menthaefolium Hochst: typical of Eritrea (where they call it “ciòmar”) with a very strong aroma; the oil is rich in methyl chavicol and anethole.
O. tenuiflorum L.: “Holy basil”; with strongly scented leaves, this is the basil used in Ayurvedic medicine and sacred to the Hindus. The extracts contain recognized anti-ageing properties that protect the heart, liver and brain from free radicals.
O. kilimandscharicum Baker: (sin. O. forskolei Benth.) × basilicum: African Blue basil is one of the few hybrid species of perennials. The best-known cultivar is the Dark Opal with lobed leaves and with a strong smell of camphor, mostly used for decorative purposes.
Some studies point out that the European varieties of basil are those that have the best aroma quality due to their high content of linalool (up to 80% of the essential oil) and limited amounts of methyl chavicol (which tends, instead, to lend an unwelcome hint of mint). Among the Italian varieties, Genovese basil is the most renowned (a DOP product), with a particularly delicate taste that is completely free of the aroma of mint (the main compound of the aroma of this variety is 77% linalool + 12% 1.8 cineol; methyl chavicol is absent); Lettuce Leaf Basil, instead, has a high level of methyl chavicol.
Egyptian basil is very similar to the European varieties but contains a higher percentage of methyl chavicol; the content of this compound is particularly high, and therefore of low quality, in basil grown on the islands of Reunion, Madagascar, Thailand and Vietnam.
Basil that comes from Java, Russia and North Africa is rich in eugenol.
Purple basil varieties are very high in anthocyanin pigments and are of great interest to the food industry.
Elements of cultivation practices
Basil is sown directly in the field by broadcasting or is sown in rows, but it can also be transplanted in rows using balled seedlings with soil at the 4-5 leaf stage. Rows should be at a distance of 20 cm. Cultivation is generally done on raised beds that are 0.80 – 1.00 m wide. Planting density in the open air varies from 15 to 40 plants per m2 and in a greenhouse with direct sowing, from 600 to 1000 plants per m2.
In the Mediterranean, the open-air cycle is typically spring-summer. Protected crops (in seedbeds or greenhouses) have an autumn-winter or late winter-spring cycle based on nominal thermal conditions and the availability and application of heat.
Basil requires frequent irrigation, top dressing and weeding.
Topping is the elimination of the apical inflorescences (flower buds) at the top of the stalks of basil. This is mainly done in family gardens and is performed with scissors or more simply, by pinching off the branch below a pair of leaflets between thumb and forefinger. Basil, as with all plants when flowers begin to form (and then its fruits), focuses all the substances produced by photosynthesis into the production of flowers, fruits and seeds. This is all at the expense of the growth of the leaves that lose their aroma and flavour and begin to precociously wither and fall. By eliminating apical inflorescences (top), the plant is stimulated to grow new shoots with fresh and fragrant leaves. The young shoots will tend to emit flowers as well, but simply repeat the procedure on each branch of basil that begins to flower; just below the point of the cut, the plant will develop two lateral branches with new leaves. Topping can be done to thicken the plant even if it is not going to flower.
In family gardens, the leaves are removed individually; harvesting can last 2-3 months.
Professional crop producers for commercial production generally uproot the plants when they reach a minimum height of 10 cm thus forming bundles of 10-15 plants that are then suitably packaged in plastic bags.
Average production is around 1.5-2.0 kg per m2.