San: Nimbah, Prabhadrah Hin,
Ben: Nim, Nim Mal: Aryaveppu
Tel: Vepa Ori: Nimba
Tam: Vembu, Veppu Pun: Bakam,Bukhain
Kan: Bevu Mar: Limbu
Importance: Neem or margose tree, also known as Indian lilac is a highly exploited medicinal plant of Indian origin, widely grown and cultivated throughout India. Every part of the tree, namely root, bark, wood, twig, leaf, flower, fruit, seed, kernel and oil has been in use from time immemorial in the Ayurvedic and Unani systems of medicine. Nimbarishta, nimbadi churna and nimbharidra khand are well known preparations. It is valuable as an antiseptic, used in the treatment of small pox. Small twigs are used as tooth brushes and as a prophylactic for mouth and teeth complaints. Extract from the leaves are useful for sores, eczema and skin diseases. Boiled and smashed leaves serve as excellent antiseptic. Decoction of leaves is used for purifying blood. Neem oil is used in soaps, toothpaste and as a hair tonic to kill lice. Seed is used in snake bite. The fruits and leaves being renewable, provide sustainable returns. Different parts of the fruit are separated into components and each one produces derivatives of varying chemical nature and utility. Neem derivatives are now used in agriculture, public health, human and veterinary medicines, toiletries, cosmetics and livestock production. Applications as pesticides, allied agrochemicals, plant nutrients and adjuvants for improving nitrogen use efficiency are of much importance. Neem kernel suspension (1%) is a house hold insecticide. Pesticide formulations containing azadirachtin are now commercially available in India, USA, Canada, Australia and Germany. Neem cake is rich in N, P, K, Ca and S. Neem Meliacins like epinimbin and nimbidin are commercially exploited for the preparation of slow and extended release of nutrients including nitrification inhibitors (Eg. Nimin). Extracts of neem seed oil and bark check the activity of male reproductive cells and prevents sperm production. Neem seed oil is more effective than the bark for birth control. Neem based commercial products are also available for diabetes treatment (Nimbola, JK-22), contraceptive effect (Sensal, Nim-76) and mosquito/ insect repelling (Srivastava, 1989; Tewari, 1992; Parmer and Katkar, 1993; Pushpangadan et al, 1993; Mariappan, 1995).
Distribution: Neem is a native of the Siwalik deccan parts of South India. It grows wild in the dry forests of Andra Pradesh, Tamil Nadu and Karnataka. It has spread to Pakistan, Bangladesh , Sri Lanka, Malaysia, Indonesia, Thailand, Middle East Sudan and Niger. It is now grown in Australia, Africa, Fiji, Mauritious, Central and South America, the Carribeans, Puerto Rico and Haiti. The largest known plantation of nearly 50,000 trees is at Arafat plains en route to Mecca in Saudi Arabia for providing shade to Haj pilgrims (Ahmed, 1988).
Botany: The genus Azadirachta of family Meliaceae comprises two species: A. indica A. Juss syn. Melia azadirachta Linn. and A. excelsa (Jack) Jacobs syn. A. integrifolia Mers., the latter being found in Philippines, Sumatra, Malaya, Borneo and New Guinea. Neem is a hardy medium to large, mostly evergreen tree attaining 20m height and 2.5m girth. It has a short bole with wide spreading branches and glabrous twigs forming a round to oval crown. The bark is thick, dark-gray with numerous longitudinal furrows and transverse cracks. Leaves are imparipinnately compound, alternate, exstipulate and 20-38cm long. Inflorescence is long, slender, axillary or terminal panicle. Flowers are white or pale yellow, small, bisexual, pentamerous and bracteate. Stamens 10; filaments unite to form a moniliform tube. Gynoecium is tricarpellary and syncarpous, ovary superior, trilocular. Each carpel bears two collateral ovules on parietal placentation. Fruit is one seeded drupe with woody endocarp, greenish yellow when ripe. Seed ellipsoid, cotyledons thick fleshy and oily. Neem has chromosome number 2n = 28. Neem trees tend to become deciduous for a brief period in dry ecology. Ecotypes, exhibiting morphological variation in root growth, leaf size, contents, bole length , canopy, inflorescence, fruit bearing, seed size, shape and quality exist in natural populations.
Agrotechnology: Neem grows in tropical arid regions with high temperatures, altitudes between 50m and 1000m, as little rainfall as 130mm/yr and long stretches of drought. Well drained sunny hill places are ideal. It grows on most kinds of soils including dry, stony, shallow, nutrient deficient soils with scanty vegetation, moderately saline and alkali soils, black cotton, compact clays and laterite crusts. However, silty flats, clayey depressions and land prone to inundation are not conducive for its growth (Chaturvedi, 1993). Soil pH of 5.0 to 10.0 is ideal. It brings surface soil to neutral pH by its leaf litter. It has extensive and deeply penetrating root system capable of extracting moisture and nutrients even from highly leached poor sandy soils.
Neem propagates easily by seed without any pretreatment, though it can be regenerated by vegetative means like root and shoot cuttings. Seeds are collected from June to August. These remain viable for 3-5 weeks only which necessitates sowing within this short time. Seeds may be depulped and soaked in water for 6 hours before sowing. Seeds are sown on nursery beds at 15x5cm spacing, covered with rotten straw and irrigated. Germination takes 15-30 days. Seedlings can be transplanted after two months of growth onwards either to polybags or to mainfield. Neem can be grown along with agricultural crops like groundnut, bean, millets, sorghum and wheat. It is also suitable for planting in roadsides, for afforestation of wastelands and under agroforestry system. For field planting, pits of size 50-75 cm cube are dug 5-6m apart, filled with top soil and well rotten manure, formed into a heap, and seedling is planted at the centre of the heap. FYM is applied at 10-20 kg/plant every year. Chemical fertilizers are not generally applied. Irrigation and weeding are required during the first year for quick establishment.
More than 38 insect pests are reported on Neem which may become serious at times. The important ones are seed and flower insect (Scirtothrips dorsalis Hood), defoliators (Boarmia variegata Moore and Eurema sp.), sap suckers (Helopeltes antonii Signoret and Pulvinaria maxima Green) , root feeders (Hototrichia consanguinea Blanchard), mealy bug (Pseudococus gilbertensis), scale insect (Parlatoria orientalis) and a leaf webber (Loboschiza Koenigiana)(Beeson, 1941, Bhasin et al, 1958, Parmar, 1995). They can be controlled by the application of 0.01-0.02% monocrotophos or dimethoate. No serious diseases are reported in Neem. Flowering starts after 5 years. In India flowering is during January-May and fruits mature from May-August. The leaves are shed during February- March and a full grown tree produces about 350 kg dry leaves and 40-50 kg berries per annum. Fresh fruits give 60% dry fruits which yield 10% kernel which contains 45% fixed oil, on an average. After 10 years of growth the wood can be cut and used as timber.
Properties and Activity: Dry Neem leaves contain carbohydrates 47-51%, crude protein 14-19%, crude fiber 11-24%, fat 2-7%, ash 7-9%, Ca 0.8-2.5% and P 0.1-0.2%. Leaves also contain the flavanoid quercetin, nimbosterol (-sitosterol), kaempferol and myricetin. Seed and oil contains desacetylnimbin, azadirachtin (C35H44O16), nimbidol, meliantriol ,tannic acid, S and amino acids. Neem cake contain the highest sulphur content of 1.07% among all the oil cakes. Trunk bark contains nimbin 0.04%, nimbinin 0.001%, nimbidin 0.4%, nimbosterol 0.03%, essential oil 0.02%, tannins 6.0 %, margosine and desacetylnimbin (Atal and Kapur, 1982; Thakur et al 1989).
Neem bark is bitter, astringent, acrid, refrigerant, depurative, antiperiodic, vulnerary, demulcent, insecticidal, liver tonic, expectorant and anthelmintic. Leaves are bitter, astringent, acrid, depurative, antiseptic, ophthalmic, anthelmintic, alexeteric, appetizer, insecticidal, demulcent and refrigerant. Seed and oil are bitter, acrid, thermogenic, purgative, emollient, anodyne, anthelmintic depurative, vulnerary, uterine stimulant, urinary astringent, pesticidal and antimicrobial (Warrier et al, 1993).