Keywords

Introduction

The Lamiaceae or formerly called Labiatae is a family of flowering plants generally known as the Ocimum or sage family, which is dispersed almost worldwide and most of the species are cultivated for their aromatic leaves and attractive flowers. These herb plants are valued for their flavor, fragrance, and medicinal properties. The plants of this family are usually cultivated by people, not only for the aroma but also for their easier cultivation, since these are readily propagated. The plants of this family have varied economic importance as the leaves of mint (Mentha viridis) are used as salad, tubers of Chinese artichoke (Stachys affinis) are consumed, and plants of other species such as Mentha, Ocimum, Melissa officinalis, and Coleus forskohlii are also used as condiments. In this chapter, various health benefits, nutritional importance, and cultivation technology of important members of the Lamiaceae family have been discussed.

Origin and Distribution

Coleus

Chinese potato/coleus or koorka or ratala in Hindi, Plectranthus rotundifolius (Poir.) Spreng Syn. Solenostemon rotundifolius (Poir.) Morton, Coleus rotundifolius, Plectranthus tuberosus, Coleus parviflorus Benth. belong to the family Lamiaceae. The chromosome number of coleus is 2n = 64. East Africa is the native place of coleus, then distributed to tropical West Africa and Southeast Asian regions such as India, Indonesia, Malaysia, and Sri Lanka (Harlan et al. 1976), but is now well adapted to Southeast Asian regions, i.e., India and Sri Lanka. The word coleus has come from Koloes, in preference to the filaments being joined and forming a tube around the style. It has aromatic, thick, and succulent leaves. Small, round to oval-shaped tubers which are dark brown are found at the base of the stem. It is extensively grown in South Indian states (Karnataka, Kerala, and Tamil Nadu) and has also been found growing on a smaller scale in Odisha, Madhya Pradesh and north eastern regions, where it is generally eaten by the tribals. It has over 200 species having both medicinal and ornamental importance. The duration of the crop is about 5 months.

Chinese Artichoke

Stachys affinis Bunge (S. sieboldii), commonly known as crosne, Japanese artichoke, knotroot, artichoke betony, and Chorogi, is inherent to China, Japan, and Korea. It is a perennial plant in which the tubers are consumed. It has been cultivated in Europe since the nineteenth century and now it is grown throughout the world. The diploid chromosome number of Chinese artichoke as reported by different workers varies from 66 to 70 (Fedorov 1974).

Hoary Basil

It is commonly known as lemon basil and American basil, while in Hindi, it is called ban-tulsi, vantulsi, or rantulsi. Botanically, it is Ocimum americanum L. syn. Ocimum canum Sims. having a chromosome number of 2n = 24. Ocimum is derived from the Greek word “ozo,” which means fragrance or smell (Paxton 1868). It has a lemon aroma that is exceptionally pure and fresh (Morales and Simon 1997) with a slight fragrance of camphor, cinnamon, and lavender. Due to its varied use in the preparation of traditional medicines, perfumes, and pharmaceutical industries, it is also known as the “king of herbs” (Simpson and Conner 1986). The genus Ocimum is the largest genera of the Lamiaceae family including more than 160 species (Pushpangadan et al. 1995). Approximately 65 species are related to Ocimum and others are regarded as synonyms (Ashraf et al. 2021; Pushpangadan et al. 1995). Ocimum is cultivated all over the world, but there are three major centers of diversity in its distribution. The tropical regions of America and Asia, as well as the tropical and subtropical regions of Africa, have the most Ocimum species (Paton et al. 1999).

Nutritional Importance and Uses

Coleus

The tubers have a special aromatic flavor and delicious taste upon cooking. In India, because of its aromatic flavor and sweetness, it is used in many curry preparations and is also baked and made into chips like a potato. The tubers also contain 20–24% starch. The tubers are a good source of minerals (calcium and iron) and vitamins (ascorbic acid, niacin, riboflavin, and thiamine) (Jayapal et al. 2016). The tuber’s scented flavor makes it a popular vegetable and apart from that it also possesses medicinal properties because of enzyme inhibitors (Prathibha et al. 1995) and flavonoids results in lowering the blood cholesterol level (Horvath et al. 2004; Abraham and Radhakrishnan 2005; Sandhya and Vijayalakshmi 2000). Tubers are also used for curing dysentery and certain eye disorders. It contains beta-carotene and α-tocopherol (vitamin E), which are known to have anticancer and antioxidant properties.

Chinese Artichoke

Chinese artichoke is valued for its rhizome, which is consumed without peeling and can be eaten raw, as salad, added to any cooked dish, curries, stir-fries, soups, casseroles, sweet and sour seafood, pickled and dried. It contains 63.6 calories, 14.3 g carbohydrates, 10.3 g fibers, 3.5 g proteins, 0.4 g total fats, 0.7 g iron, and 25.2 mg calcium per 100 g of edible portion. It is a tasty, culinary vegetable with a crisp, crunchy texture and an artichoke-like sweetness and nutty flavor. The tubers have a novel appearance, so these are used as a whole, rather than chopped. As the tubers do not have a proper shape, it is very difficult to clean the tubers. Tubers are pickled in China and Japan.

Vacuoles in the tuber are rich in stachyose, a tetrasaccharide, consisting of galactose, glucose, and fructose. Stachyose can be up to 80–90% in dry tubers.

Hoary Basil

It contains 87 g water, 3.3 g protein, 2.0 g fiber, 320 mg Ca, 4.5 mg Fe, 27 mg vitamin C, and 180 kJ energy per 100 g edible part. It contains aroma compounds like citral, camphor, and methyl cinnamate in varying proportions, which is responsible for its cinnamon, clove, and lemon-like fragrance. Lemon basil is used widely in soups, stews, curries, and stir-fried dishes. It is used mostly in Indonesian cuisine, where it is called kemangi, and is often used for seasoning curries, soups, stew, steamed, and grilled dishes. In Thailand, it is known as maenglak and is among the several basils used in Thai cuisine (Prakash and Gupta 2005). In patients with gastric, chronic fever, dysentery, hemorrhage, dyspepsia, and hepatic disorders, a juice of tulsi leaves has been recommended to help them recover faster. Its leaf juice along with Triphala is used in the preparation of Ayurvedic eye drop, which is suggested for treating various painful eye diseases like glaucoma, cataract, and chronic conjunctivitis. Its essential oil is extracted and used in soaps and cosmetics. It is also used to extract essential oils, which has both medicinal and industrial applications. The whole plant has hemolytic activity (Sutili et al. 2016), antifungal activity (Sethi et al. 2013), bactericidal activity (Vieira et al. 2014), antimicrobial activity (Thaweboon and Thaweboon 2009), antioxidant activity (Aluko et al. 2013a), and hepatoprotective activity (Aluko et al. 2013b), and the leaves possess analgesic and anti-inflammatory activity (Sripriya and Venkanna 2013), immunomodulatory activity (Sunitha and Begum 2013), and anesthetic activity (Silva et al. 2015).

Botany and Taxonomy

Coleus

It is a small annual bushy herb or under the shrub, can reach to 30–60 cm height, and forms dark brown colored round to oval-shaped small underground tubers with aromatic flavor in about 5 months. The tips of the adventitious roots are modified into small round tubers. It is also called a Hausa potato and has a prostrate or ascending stem. It has simple thick and aromatic leaves (exstipulate) and plants have a purple-colored mark on the central portion of the leaf lamina. Opoku-Agyeman et al. (2007) reported that the color of leaves is primarily green (>90%) with other deviations, i.e., green, light-green, and olive-green. Three landraces of Plectranthus esculentus are known, namely Bebot, Riyom, and Longat, whereas Solenostemon rotundifolius has two varieties, S. rotundifolius var. nigra and S. rotundifolius var. alba (Agyeno et al. 2014). The flowers are either hermaphrodite or male-sterile, pedicellate, and ebracteate. Small flowers are arranged in racemose cymes. The corolla is uniformly greenish-brown and violet colored, sympetalous, two-lipped, and rarely one-lipped. There are four stamens, violet-colored anthers, and stigma, which bear a cluster of dark brown, heteromorph tubes and superior four-lobed ovaries which yield four one-seeded nutlets. The fruit is carcerulus with persistent calyx and the seed is non-endospermic. The plants parts of Chinese potato are shown in Fig. 7.1.

Fig. 7.1
Three photos. A. Chinese potato plants with clusters of leaves. B. a sprig with flowers. C. small tubers.

Chinese potato: (a) plant, (b) flowers, and (c) tubers

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At the base of the primary stem, the coleus produces small clusters of starchy, brown, or black aromatic tubers. S. rotundifolius produces small-sized tubers (Prematilake 2010), whereas in India and Sri Lanka, large-sized tubers are produced (Opoku-Agyeman et al. 2007). The skin color of tubers can be red or white or black (Dittoh et al. 1998). As per the skin color, S. rotundifolius has three varieties, i.e., var. nigra A. Chev. has a black color, var. rubra A. Chev. has a reddish-gray or reddish-yellow color, and var. alba A. Chev has a white color (Tindall 1983). Despite the differences in skin color, the flesh color of tubers in all three varieties is white (Opoku-Agyeman et al. 2007).

Chinese Artichoke

Stachys affinis is a perennial herbaceous plant originating from north-western China. It is a perennial, erect, or inclined deciduous plant having a stem height of 30–120 cm. Leaves are ovate-cordate to ovate-oblong, 2.5–9.5 cm long and 1.5–3.5 cm wide (Fig. 7.2).

Fig. 7.2
3 photos. A. Chinese artichoke plants with leaves and small sprouting buds. B. flowers with small petals. C. tubers in the shape of small spirals.

Chinese artichoke, Stachys affinis: (a) plant, (b) flowers, and (c) tubers

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Flowers are ovoid, 1.5 cm in diameter, tuberculate, and red to purple. The tubers are small, convoluted, and indented. The tuber skin is thin, whitish-brown, or ivory-white. The tuber flesh is tender and of white color. Chinese poets compare the plant to jade beads since its structure is like beads.

Hoary Basil

It is valued for its young leaves and tips, which have a strong minty aroma, and it is used in various cuisines in Arab, Indonesia, Philippines, Lao, Malay, Persia, and Thailand. The plant is perennial, bushy, and vigorous which grows to about 15–60 cm in height and has subquadrangular striate branches (Fig. 7.3).

Fig. 7.3
3 photos. a, Hoary basil plants. b. a thick stem with medium-sized flowers. c. a stem starting to bear fruits in small buds.

Hoary basil, Ocimum americanum: (a) plant, (b) flowers, and (c) fruits

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Leaves are elliptical lanceolate, entire or faintly toothed, glabrous, and gland-dotted. The flowers’ color may be white or pink or purple arranged in elongated racemes. Fruits are small notelets, pitted, and mucilaginous when wet and generally found growing in open fields and wastelands.

Climate and Soil

Coleus

It can grow over a varied range of climate and soil conditions (Agyeno et al. 2014). Unlike other tuber crops, it is a transplanted vegetable. Coleus can grow well under both tropical and subtropical conditions but comes up well in a hot, humid climate where there is no incidence of frost. Cooler nights and hot humid days favor tuberization. Moreover, it requires a frost-free growth period. Like yam bean, it requires evenly distributed rainfall during its growth period and cannot withstand drought conditions. The ideal temperature for its growth and development ranges from 25 to 30 °C. It can grow in any type of soil, provided it is rich in organic matter and well-drained. However, for optimum yield, sandy loam to alluvial soils is the best. Waterlogged soils should be avoided as too much moisture reduces the tuber yields. For this reason, it is desirable to grow the crop on ridges than on flatbeds. It thrives best in soils with pH ranging from slightly acidic to neutral (5.5–7.0), which is suitable for its cultivation.

Chinese Artichoke

It prefers light, well-drained soil with good sunlight and can thrive in normal garden soil. It grows best in well-manured soil that does not dry out during the growing season. Plants can even withstand waterlogging conditions during winter.

Hoary Basil

The optimum temperature required for germination is 20–24 °C. It takes about 5–14 days for germination. Its growth occurs best in an area that receives full sunlight for at least 6 h. The plants are very hardy and can tolerate winter when grown in subtropical and tropical regions.

Agronomic Practices

Coleus

Propagation is mostly done by vine cuttings; therefore, for the production of vine cuttings, approximately 150–170 kg tubers are sufficient for 500 m2 area which produce cuttings for one hectare area. Usually, tuber cuttings are taken from the previous season and before planting of tubers, 100–200 kg of well-decomposed farmyard manure is added in the nursery bed. The planting of tubers is done in April–May in the nursery bed and then transplanted the cuttings in the main field after 30–40 days. Usually, 1 kg of the tuber is sufficient to plant about 75–100 m2 area. To minimize the requirement for seed tubers, the tubers are first planted in the nursery. The tubers start sprouting within 15 days and give rise to several sprouts. These sprouts grow to a height of 15–20 cm in about 3 weeks and can be readily transplanted in the field. Stem cuttings from these sprouts with a length of 10–20 cm can also be used as planting material, but planting suckers directly is desired for better establishment. Top suckers having 4–5 leaves are picked up and transplanted in the field. Within another 15 days, the initially planted tubers again form a cluster of sprouts ready to transplant in the field. This way, when the top suckers are picked at intervals from the nursery bed, 50 kg seed tubers can form enough suckers in about 2 months to plant a one-hectare area. However, in this case, staggered planting has to be followed.

The land for growing coleus should be thoroughly ploughed, leveled, and brought to fine tilth after adding 10–25 tons of well-decomposed farmyard manure or compost. The crop can be raised in both upland and lowland areas provided there is no waterlogging. The crop can be raised either on flat raised beds or small ridges. Seed tubers weighing about 7–10 g are planted at a spacing of 90 cm × 20 cm to achieve high yield (Bayorbor and Gumah 2007). In Kerala, however, the recommended spacing for coleus cultivation is 45 cm × 30 cm (Ravindran et al. 2013). While planting, a spacing of 60 cm × 30 cm is maintained, thus accommodating 55,000 plants per hectare. Fifteen to 20 cm long stem cuttings with 5 leaves are planted on 15–20 cm high ridges. The ridges are made at a distance of 30–50 cm. A plant spacing of 60 cm × 45 cm (Hrishi and Kumar 1976) or 60 cm × 15 cm (Geetha 1983) is also suggested for coleus.

Besides the ordinary ridge method, coiled planting and horizontal planting methods are also practiced. In the coiled planting method, 22 cm long stem cutting is used and about 12 cm of the more mature portion is coiled and planted in 7 cm wide and 5 cm deep holes, whereas in the horizontal planting method, 30 cm long stem cuttings are used and two similar cuttings are kept sidewise in opposite directions touching each other across the ridges. A two-thirds portion of these stem cuttings is placed in the soil, while the remaining portion projects outside the ridges. This way, planting the stem cuttings in pairs at a distance of 7–10 cm requires more planting material. Among these three methods, the coiled planting method gives maximum tuber yield. It has been observed that dense planting produces smaller-sized tubers but suppresses the weeds.

July–August or November–December is the ideal season for planting coleus in the main field. However, planting during the first week of October gives the highest tuber yield followed by planting in January and September (Singh and Mandal 1976). The later planting season can be followed in areas where irrigation facilities are available. In most parts of India, its cultivation is done during the rainy season. Two or three weeding can be done as per the requirement. Two months after planting, earthing up can be done.

Chinese Artichoke

Usually, it is propagated by tubers and very rarely by cuttings. It can also be propagated via seeds but seeds are scarce. It is vegetatively propagated using tubers in the spring season, i.e., from March to May. The tubers are planted into a pit of 30 cm × 30 cm size at a depth of 5–8 cm. Weeding is compulsory but care should be taken that the roots are not damaged. It is important to ensure that adequate water is supplied during the summer season. The plants are very tolerant to a higher temperature during the summer season. The tubers sprout when the temperature is more than 5 °C. Tuber development requires about 5–7 months. Flowering starts from July to August, while fruit set takes place in September.

Hoary Basil

It is usually propagated by seeds, which are sown in a seedbed and germinate after 1–2 weeks of sowing with epigeal germination. For indoor planting, March to April is the suitable time, while for outdoor conditions April to June is suitable. The seedlings are transplanted after 3–4 weeks at a distance of 20–30 cm. The young leaves should be picked before flowering, for promoting the growth of more leaves and branches. June to September is the flowering season. After 8–12 weeks of sowing, when the plants are about 25 cm tall, they begin to flower, and the plant continues to flower until it dies.

Nutrient Management

Coleus

The field is manured and fertilized before planting by adding 10 tons of farmyard manure per hectare. According to a field experiment conducted by Kerala Agriculture University, one hectare of cuttings can be fertilized with 1–2 doses of 40–60:60:100 kg/ha N:P:K. In addition to 10 tons of FYM, 30 kg of nitrogen and 50 kg of potash along with 60 kg of phosphorus per hectare can be added during earthing up. The application of fertilizer in split doses is very important. Thirty kilograms of nitrogen/ha along with 2 kg of Azospirillum can be applied 30 days after planting at the time of earthing up. If the soil gets removed from the basal portion of the plant, earthing up can be done again to encourage tuber production. Earthing up covers a basal portion of the stem with soil, which promotes tuberization and tuber development. The second earthing up can be done 1 month after the first earthing up. Danya and Potty (2007) reported siderophore production by Pseudomonas fluorescens from the rhizosphere of Chinese potato.

Varieties

Coleus

In different regions of India, generally, local cultivars are popular, which are of two types, small-sized tubers with good flavor and large-sized tubers having higher yield.

The cultivar Sree Dhara, which was released by Kerala Agriculture University (KAU), recorded a higher yield ranging from 25 to 29 tonnes/ha over 6 months.

Nidhi is a medicinal cultivar resistant to major pests; nematodes have been released by KAU for cultivation, which matures 15 days earlier than conventional types and takes approximately 135 days for maturity, and produces 27 tons/ha yield.

Harvesting and Yield

Coleus

When the vines get dried, about 4–5 months after planting, harvesting can be done by pulling out the plants, and the remaining tubers are removed from the soil. The yield may range from 15 to 20 tons/ha in 120 days.

Chinese Artichoke

The tubers are manually harvested after 6–8 months of planting. The smaller size and dispersed growth of tubers in the soil make the harvesting more time-consuming. Tubers can be harvested from October onwards. Though the above-ground portion of the plant can be damaged by frost, the tubers being very hardy can be left underground during the winter and are harvested as and when required. Under optimum growing conditions, a plant may give rise to about 40–220 tubers depending on the planting material, and the yield of 8–20 tons/ha can be obtained. The tubers dry out and get discolored if kept in the open air; therefore, tubers should be marketed immediately after harvesting.

Hoary Basil

Harvesting can be done after 2–3 months of planting. Harvesting of leaves can be done from July to September at regular intervals but the plant should never be completely defoliated. Usually, young shoots of 10 cm in length are harvested, but the whole plant can also be cut along with roots. Seeds mature after 14–20 weeks from sowing. The dried inflorescences are cut, sun-dried, and threshed by beating.

Plant Protection

Coleus

Root-knot nematode is a serious coleus problem that causes severe swelling or gall formation in the roots, thereby resulting in suppressed root growth, stunting, and wilting. The nematodes enter the seedling’s roots when it is most vulnerable. Therefore, nematodes can be controlled by sowing tubers that are free from nematodes. Deep ploughing is done to expose the soil and kill the nematodes. Summer fallowing and soil solarization can be practiced. Sweet potato variety Sree Bhadra can be cultivated as a preceding crop during May–June, which helps in trapping root-knot nematodes in the soil.

Before planting, dip the vines in an insecticidal solution for about 10 min to control leaf folding caterpillars and vine borers. In case of severe damage in the field, insecticides can be sprayed at 1 ml/l.

Conclusion

Chinese potato, Chinese artichoke, and hoary basil are important minor vegetables of the Lamiaceae family having several uses. Being nutritionally important, there is good potential to bring these vegetables under cultivation in a suitable cropping pattern. There is a need to increase awareness about the cultivation and consumption of these valuable vegetables so that more people can include these in their balanced diet to get multiple health benefits. Furthermore, the different value-added products prepared by utilizing these vegetables can also be popularized among urban residents, simultaneously enhancing the income of resource-poor farmers.