Micropropagation provides rapid reliable system for the production of large number of genetically uniform, plantlets compared to conventional methods and large number of selected types of plants are made available in relatively short period of time. In the recent years there is a growing realization on in vitm techniques for medicinal plants which serve as a potential solution not only for rapid multiplication but also for conservation of germplasm of medicinal plants. Tissue culture has become a very useful system for the mass propagation of the medicinal plants. Plants being the major source of medicine and fundamental to the well being of mankind. During the past decade there has been considerable demand for the plant based natural products because of wide spread awareness regarding the harmful effects of chemicals. Hence the increasing demand for large scale production of medicinal plants can be best met by tissue culture techniques over the conventional methods. During the past two decades, there has been a great interest and progress in in vitm propagation of medicinal plants using techniques of tissue, meristem protoplast and organ culture. Gau et al. (1993) have reported that the adventitious bud could be regenerated from different sources of medicinal plants.
Stevia mbaudiana is a natural non-calorie sweetner belonging to eupatory tribe of the composite family and is a native of north-eastern Paraguay. Stevia rebaudiana has immense medicinal importance. Stevia is useful far hypoglycemia, diabetes, cardiovascular problems, antimicrobial action and skin problems. No ill effects on the body system by the use of stevia has been reported, so far. The leaves of Stevja rebaudiana plant is used in Paraguay as a sweetner and herbal remedy. Stevia sugar obtained from the leaves of stevia contain compounds about 250 times as sweet as table sugar (Shcok 1982). Coleus forskohlii belongs to the family Lamiaceae the plant grows to a height of 45-60 cms possess thick roots the leaves are larger (7.5 to 12.5 cm) and with (3 to 5 cms) roots are tuberous. The crop is known to have originated in the Indian subcontinent and is bistributed in subtropical Himalayas, Southern India and Sri Lanka. Coleus forskohlii is an Indian herb known for the source of forskolin (Desouta and Shah, 1988). The roots are the main source of the compound forskolin is used in medicine and for treatment of certain health problem like cardiac insufficiency, hypertension. glaucoma, thrombosis, asthma and metastatic conditions (Seaman 1984). Gerbera jamesonii belonging to family Asteraceae, is one of the nature's beautiful creations and is one amongst the top ten cut flowers of the
world, having excellent flowers of exquisite shape, size and bewitching colours. The flowers having long shelf life of nearly 10 to 12 days lend themselves beautiful to different floral arrangements in vases. Tissue culture plants although, green in colour are poor photosynthesizer because of high relative humidity inside the culture vessel (over 95%) and lack proper mechanisms to contrdl water loss. These plants if, transferred directly to the hardening chamber they show very poor survival. Hence, acclimatization of plantlets is commonly done inside the green house. Hardening of plantlets to make them adapt to the outside environment is critical process due to anatomical and physiological peculiarities of the plantlets. One of the major obstacle in the application of tissue culture methods for plant propagation has been the difficulty in successful transfer of plantlets from laboratory to the field. Thus, transpiant shock can be avoided if, bioinoculants are added so that the plants sunrive in a new environment. Soil microorganisms as biofertilirer have occupied a special significance in this respect. Mycorrhization of micropropagated plants during weaning stage decreases the mortality rate of the plantlets by increasing the hydrolytic conductance and resistance to water loss. Either by formation of epicuticular wax or by regulation of stomata. Application of AMF mycorrhira appears to play a key role in favouring ex vitm development of micropropagated plants (Verma and Schupp 1994,1995,1999).
Pirifomaspora indice a newly described endophyte interacts with the roots of great variety of plants, showing a positive effect on biomass production, it provides protection to the tissue culture raised plantlets by over coming the "transcent transplant shock on transfer to the field rendering almost 100% survival" (Ajit Varma 1999). Trichoderma spp. have been used extensively for bioeontrol of soil borne plant pathogens (Jeyarajan and Angappan 1988). The plant growth promoting fungus Trkhoderma and association with VAM fungi has proved to increase growth and yield of several horticultural plants. Synergistic effect of vesicular arbuscular mycorrhizal fungi and plant growth promoting microorganisms has been reported in many plants but not much work has been done on the interaction of VAM and PGPM on medicinal and horticultural plants keeping this in view the importance of beneficial microorganisms and the priority areas of medicinal plant research, greater emphasis was given in our studies on in vitro propagation of medicinal and flori-horticulture plants and synergistic interaction of beneficial microorganisms under the following objectives : 1. To standardize the culture media and growing conditions for the in vitm propagated medicinal plants Stevia rebaudiana, Coleus forskohlii, GenSera jamesonii.
2. Different explants ware subjected and induced to develop plantlets in in vitm on Murashige & Skoog (1962) medium supplemented with different concentration and combination of growth hormones. 3. To develop techniques in green house rate for maximum survival and establishment of plantlets obtained through micropropagation. The plantlets were treated with different bio-inoculants during hardening. 4. Influence of beneficial microorganisms on micropropagated medicinal and horticultural plants and their growth parameters were assessed.