Basil


Basil, also called great basil, is a culinary herb of the family Lamiaceae. It is a tender plant, and is used in cuisines worldwide. In Western cuisine, the generic term "basil" refers to the variety also known as Genovese basil or sweet basil. Basil is native to tropical regions from Central Africa to Southeast Asia. In temperate climates basil is treated as an annual plant, but it can be grown as a short-lived perennial or biennial in warmer horticultural zones with tropical or Mediterranean climates.
There are many varieties of basil including sweet basil, Thai basil, and Mrs. Burns' Lemon. O. basilicum can cross-pollinate with other species of the Ocimum genus, producing hybrids such as lemon basil and African blue basil.

Description

Basil is an annual, or sometimes perennial, herb. Depending on the variety, plants can reach heights of between. Basil leaves are glossy and ovulate, with smooth or slightly toothed edges that typically cup slightly; the leaves are arranged oppositely along the square stems. Leaves may be green or purple. Its flowers are small and white, and grow from a central inflorescence, or spike, that emerges from the central stem atop the plant. Unusual among Lamiaceae, the four stamens and the pistil are not pushed under the upper lip of the corolla, but lie over the inferior lip. After entomophilous pollination, the corolla falls off and four round achenes develop inside the bilabiate calyx.

Phytochemistry

The various basils have such distinct scents because the volatile aromatic compounds vary with cultivars. The essential oil from European basil contains high concentrations of linalool and methyl chavicol, in a ratio of about 3:1. Other constituents include: 1,8-cineole, eugenol, and myrcene, among others. The clove scent of sweet basil is derived from eugenol. The aroma profile of basil includes 1,8-cineole and methyl eugenol. In this species eugenol is synthesised from coniferyl acetate and NADPH.

Similar species

Some similar species in the same genus may be commonly called "basil", although they are not varieties of Ocimum basilicum.
The exact taxonomy of basil is uncertain due to the immense number of cultivars, its ready polymorphy, and frequent cross-pollination with other members of the genus Ocimum and within the species. Ocimum basilicum has at least 60 varieties, which further complicates taxonomy.

Cultivars

Most basils are cultivars of sweet basil. Most basil varieties have green leaves, but a few are purple, such as, 'Purple Delight'.
The name "basil" comes from the Latin basilius, and the Greek βασιλικόν φυτόν, meaning "royal/kingly plant", possibly because the plant was believed to have been used in production of royal perfumes. Basil is likewise sometimes referred to in French as "l'herbe royale". The Latin name has been confused with basilisk, as it was supposed to be an antidote to the basilisk's venom.

Distribution and habitat

Basil is native to India and other tropical regions stretching from Africa to South East Asia, but has now become globalized due to human cultivation.

Cultivation

Growing conditions

Basil is sensitive to cold, with best growth in hot, dry conditions. Basil prefers high light conditions and grows best under full sun conditions. Increasing light intensity, particularly the photosynthetic photon flux density, can significantly enhance the plant's fresh weight, dry matter content, and height.
However, due to its common use, basil is cultivated in many countries around the world. Production areas include countries in the Mediterranean area, those in the temperate zone, and others in subtropical climates.
In Northern Europe, Canada, the northern states of the U.S., and the South Island of New Zealand, basil grows best if sown under glass in a peat pot, then planted out in late spring/early summer ; however, it can also thrive when planted outside in these climates. Additionally, it may be sown in soil once chance of frost is past. It fares best in well-drained soil with direct exposure to the sun.
Although basil grows best outdoors, it can be grown indoors in a pot and, like most herbs, will do best on a sun-facing windowsill, kept away from cold drafts. A greenhouse or row cover is ideal if available. It can, however, even be grown in a basement under fluorescent lights. Supplemental lighting produces greater biomass and phenol production, with red + blue specifically increasing growth and flower bud production. increases the volatiles in O. basilicum essential oil, which has not been reproducible in other plants, and so may be unique to the genus or even to this species.
Basil prefers well-drained organic soils, as adequate oxygen availability in the root zone is essential for optimal plant growth. Poor soil drainage can lead to root hypoxia, which negatively affects overall plant development and essential oil yield.

Pruning, flowering, and seeding

Once a stem produces flowers, foliage production stops on that stem, the stem becomes woody, and essential oil production declines. To prevent this, a basil-grower may pinch off any flower stems before they are fully mature. Because only the blooming stem is so affected, some stems can be pinched for leaf production, while others are left to bloom for decoration or seeds. Picking the leaves off the plant helps promote growth, largely because the plant responds by converting pairs of leaflets next to the topmost leaves into new stems.
Once the plant is allowed to flower, it may produce seed pods containing small black seeds, which can be saved and planted the following year. If allowed to go to seed, a basil plant will grow back the next year.

Propagation methods

Seeds

The optimal germination temperature for basil seeds ranges between 34.5–39.0°C, while the base germination temperature lies between 9.8–13.2°C. No significant variation in optimal germination temperature has been observed among different basil cultivars. Prior to sowing, basil seeds can be hydroprimed by soaking in water for 12 hours, which effectively enhances germination rates and seedling vigor.

Cuttings

Basil is commonly propagated through cuttings. Compared to seed propagation, basil cuttings tend to result in earlier harvest and higher yield. The typical propagation method involves selecting healthy, non-lignified stem segments approximately 5–10 cm in length, preferably apical shoots that retain 2 to 5 leaves, which are then inserted into moist soil until root development occurs. After rooting, the plantlets are transplanted into the field. Exposing basil cuttings to blue light significantly accelerates root formation, thereby shortening the growth period.

Diseases

Basil suffers from several plant pathogens that can ruin the crop and reduce yield. Fusarium wilt is a soil-borne fungal disease that will quickly kill younger basil plants. Seedlings may be killed by Pythium damping off. A common foliar disease of basil is gray mold caused by Botrytis cinerea; it can cause infections post-harvest and is capable of killing the entire plant. Black spot can be seen on basil foliage and is caused by the fungi genus Colletotrichum. Downy mildew caused by Peronospora belbahrii is a significant disease, as first reported in Italy in 2003. It was reported in the Florida in 2007 and by 2008 had spread along the eastern United States, reaching Canada. Basil cultivars resistant to P. belbahrii have been developed.
Non-pathogenic bacteria found on basil include Novosphingobium species.

Uses

Culinary

Basil is most commonly used fresh in recipes. In general, it is added last, as cooking quickly destroys the flavor. The fresh herb can be kept for a short time in plastic bags in the refrigerator, or for a longer period in the freezer, after being blanched quickly in boiling water. It has a flavor resembling that of liquorice.

Leaves and flowers

The most commonly used Mediterranean basil cultivars are "Genovese", "Purple Ruffles", "Mammoth", "Cinnamon", "Lemon", "Globe", and "African Blue". Basil is one of the main ingredients in pesto, an Italian sauce with olive oil and basil as its primary ingredients, and is used in other sauces and salad dressings. Many national cuisines use fresh or dried basils in soups and other foods, such as to thicken soups. Basil is commonly steeped in cream or milk to create flavor in ice cream or chocolate truffles. It is sometimes used to infuse oils and vinegars.
Lemon basil has a strong lemony smell and flavor due to the presence of citral. It is widely used in Indonesia, where it is called kemangi and served raw as an accompaniment to meat or fish.

Seeds

When soaked in water, the seeds of several basil varieties become gelatinous, and are used in Asian drinks and desserts such as the Indian faluda, the Iranian, or hột é. In Kashmir, the Ramadan fast is often broken with babre beole, a sharbat made with basil seeds.

Folk medicine

Basil is used in folk medicine practices, such as those of Ayurveda or traditional Chinese medicine.