Cultivation of Medicinal and Aromatic Plants in India - a Commercial Approach

India (8-30 N and 68-97.5 E) exhibits a wide range in topography and climate, which has a bearing on its vegetation and floristic composition. This subcontinent is one of the World’s 12 leading Biodiversity Centres, encompassing 16 different agro-climatic zones, 10 vegetation zones, 25 biotic provinces and about 426 habitats of specific species. It has been estimated that about 45,000 plant species (nearly 20% of the global species) occurs in the Indian Sub-continent. About 3,500 species of both higher and lower plant groups are of medicinal values. More than 80 percent of medicinal and aromatic plants (MAP) are collected from 17 million hectares of Indian forest land. However, many of these, due to over-exploitation have become rare (Rheum emodi, Aconitum deinorrhizum), threatened (Rauvolfia serpentina, Berberis artistata), or endangered ones (Sassurea lappa, Dioscorea deltoidea). Problems arising out of rapid genetic loss of medicinal plants forced the need for international co-operation and co-ordination to undertake programmes for conservation of medicinal plants to ensure that adequate quantities are available for future generations. Cultivation of medicinal and aromatic species gives scope to improve the quality of the drugs. Merits of commercial cultivation of MAP is the outcome of implementation of number of critical factors like locate-selection; good genetically stable planting materials; good agrotechnological practices; nutrient input; harvesting management and implementation of suitable post harvesting techniques to preserve the end product till smart and effective marketing arrangements are made. There is a growing demand today for plant-based medicines, health products, pharmaceuticals, food supplements, cosmetics etc. in the international market. The international market of medicinal plants is over 60 billion US dollar per year, which is growing at the rate of 7 percent per annum. The present export of herbal raw materials and medicines from India is about US dollar 100-114 million approximately per year. India is one of the major exporter of crude drugs mainly to six developed countries viz. USA, Germany, France, Switzerland, U.K. and Japan, who share between them 75-80 per cent of the total export market. CULTIVATION OF MEDICINAL AND AROMATIC PLANTS (MAP) IN INDIA Techno-economical Considerations for Cultivation of MAP in India Loss of genetic diversity, particularly related to potential medicinal species has taken place; more so in the Worlds’ tropical rain forests and its conservation aspect has, of late, captured the attention of herbal scientists and experts (Duke, 1985). With emphasis it can be stated that the ultimate solution of medicinal plant conservation is medicinal plant cultivation in a scientific way (Foster, 1993). Botanical producer will desire to optimise yield from production; whereas user or entrepreneur will want to manufacture a product of uniform quality. Environmental factors play dramatic roles on biomass yield and composition, and also on its consistency. Proc. Int. Conf. on MAP Eds. J. Bernáth et al. Acta Hort. 576, ISHS 2002 192 The process of selection of geographical site is very important and will have to be tailormade to meet the requirement of a particular botanical or a group of botanicals with ecological homogeneity. Elevation of the region has a profound bearing on successful cultivation of MAP. Indian cultivation of Datura innoxia, Atropa belladona, Catharanthus roseus, Rauvolfia serpentina, Cepecacuanha spp. and Hyoscyamus niger are appropriate examples (Table 1). Slope face is another factor, which determines variations of diurnal light intensity and temperature necessary for better growth and development of MAP. Latitude also have pronounced effect on biomass composition e.g. Atropa belladona. Adequate soil moisture and moderate nutrient status generally meet the requirements for growing MAP in India. However in some cases (e.g. Psyllium, Cassia, Catharanthus, Withania, Rauvolfia, Cymbopogon), the plantation can profitably thrive on low fertility soils of warmer regions. Pyrethrum, Solanum spp., Jasminium and Ocimum spp. can be economically grown over medium fertility soils. In case of Papaver, Dioscorea spp., Mentha spp. and Cymbopogon spp., high fertility soil and liberal irrigation will be necessary for successful growth of plantation. Rained cultivation in India is widely followed in Withania, Cassia, Vetiveria and Eucalyptus citriodora. Medicinal and aromatic crops are generally adapted to a wide range of soil texture and pH. Plantago, Cassia, Cymbopogon growing over light soils become high yielding when grown over loam and clay loam (nearly 80% increase in yield in case of Plantago ovata). Vetiveria is unique for its tolerance to soil alkalinity and periodic flooding and water logging of fields; conditions however producing no adverse effect on total oil yield and its composition. Cinchona, Cephalis and Coptis have preference for acidic soils (5-6 pH); whereas species like Aloe, Pandanus, Urginea, Commiphora are grown in soils of higher pH. Day length have been found to influence growth and development of certain medicinal and aromatic crops in India. Commercial cultivation of Mentha, Glycyrrhiza, Coptis, Humulus prefer more than 14 hours of day length for high crop yield whereas citronella, Pelargonium and Pogostemon are short-day plants and essential oil production can be increased by nearly 25% by satisfying appropriate light requirements to these crops. Senna is a day-neutral plant and cultivation success is independent of prevalent day-light duration. In crops like Solanum, Digitalis, Rauvolfia and Dioscorea, effects of photoperiodic cycles (long days) have also been clearly established (Chatterjee, 1986). Regulatory role of light intensity on improvement of performance of a number of medicinally important crops has been established. In Mentha, ample sunshine is necessary at maturity for higher content of oil and menthol content. Economics of cultivation of this species is very much affected if crops are harvested in rainy or cloudy days due to the fact that higher conversion of menthol into menthone. Amongst other plantation crops, low light intensity favours production like Cephalis; thereby necessitating artificial shading during commercial cultivation. Only 20-25 percent day light intensity is recommended for optimum productivity performance. Berberine content is nearly 10-15 percent higher in roots of Coptis japonica, when on average, 70 percent of incident light is intercepted. Additional light promotes the AP accumulation in Digitalis spp. and Solanum khasianum (Table 2.). Reduced light intensity (nearly 40 %) by growing Cinchona under shade tree increases percentage of quinine and related alkaloids by more than 30 percent; as well as bark yield by 30-40 % (Table 3). Role of atmospheric temperature on success of medicinal and aromatic plant cultivation can also be well exemplified. Pyrethrum growing in southern hills is favoured by lower minimum temperature increasing the yield of dry matter and total pyrethrin contents. In general increasing temperature up to a maximum (prior to physiological damage) favour increased secondary metabolite production in many alkaloid and terpene producing medicinal plants. Composition of secondary metabolite may also be changed. Low temperature favours morphine increase in poppy and decreases the total principle content.