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Miscellaneous

Miscellaneous: 

Tissue Culture and In-Vitro Conservation of Spices

Introduction 
The productivity of many of spice crops is considerably low due to various factors such as inadequate availability of high yielding varieties, absence of genotypes resistant to pests and diseases and absence of variability in many of the introduced crops. Biotechnology with its apparently unlimited potential offers new and exciting opportunities to address the above crop specific problems. Some of the important applications of biotechnology in spices are; micro propagation and rapid clonal multiplication of high yielding 'elite' genotypes to generate good quality planting material; exploiting somaclonal variation and genetic engineering techniques for crop improvement; in vitro selection for resistance to biotic and abiotic stresses; in vitro conservation and safe exchange of germplasm and production of flavor and volatile constituents in culture.

This paper reviews the present status of biotechnology of spices with emphasis on the work done in India.

Cardamom 
'Katte' disease caused by virus is one of the major production constraints in cardamom. Utilisation of virus-free planting material is considered the most important input in disease management programme and to check disease spread.

Clonal Multiplication 
Cardamom is multiplied vegetatively as well as through seed. Being a cross pollinated crop, clones are ideal for generating true to type planting material from high yielding clumps. However, due to inadequate availability of clonal planting material, farmers still prefer seedlings. In vitro propagation method for clonal propagation of cardamom has been standardized.

High rate of multiplication coupled with additional advantage of obtaining uniform and disease free planting material makes micro propagation a preferred method to conventional method. Field evaluation of tissue cultured plants was carried out at Indian Institute of Spices Research (IISR). Preliminary results showed that the micro propagated plants performed on par with suckers of the original mother plant. However, Nadgauda, Mascarenhas & Madhusoodanan reported that the tissue cultured plants were superior to that of seedling progenies.

Regeneration of plantlets from Callus 
Rao et. al. reported successful regeneration of plantlets from callus of seedling explants of cardamom. Protocols for organogenesis and plant regeneration from rhizome and vegetative bud-derived callus cultures were also standardized (with about 20-50 plantlets per culture) at IISR which are being used for large scale production of somaclones and selection of useful genotypes. High amount of variability was noticed among the somaclones for the morphological characters in the culture vessels itself. Somaclones are being evaluated in the field at IISR for their genetic variability. Efficient plant regeneration systems are essential for future genetic manipulation to evolve resistant genotypes for combating biotic and abiotic stress.

Inflorescence Culture 
Immature inflorescences form an excellent source for clonal multiplication of cardamom through tissue culture especially when other sources are prone to high rate of contamination. Kumar et al. reported the successful conversion of immature floral buds to vegetative buds and subsequently to plantlets.

A new curing chamber for large cardamom 

Results 
The gasifier-based drier helps cardamom growers in two ways compared to the conventional driers. It improves the quality of dried cardamom capsules by retaining the natural reddish color, retaining 35% more volatile oil, and by avoiding the burnt smell; secondly, it burns fuel more efficiently, resulting in substantial (more than 60%) fuel saving.

The processing of large cardamom using gasifier-based systems would save over 12,000 tonnes of fuel annually in Sikkim alone.

Problem 
Fresh cardamom capsules generally contain 80-85% (wet basis) moisture. For long-duration storage for the market and also for bringing out the aroma of cardamom, the moisture content of fresh cardamom has to be brought down to less than 10% by drying the capsules. Most of the farmers still use the traditional cardamom curing system for drying large cardamom. Under this system, fresh cardamom capsules are dried in locally made chambers, known as bhattis that are constructed out of rocks, stones, and bamboo. This traditional curing system, however, has several drawbacks. It produces excessive smoke and thus spoils the true flavor of cardamom. The cardamom capsules get covered by soot, are charred, and often unevenly dried. They also lose a high percentage of oil in the drying process. Further, the operating thermal efficiency levels of the traditional system, known as bhattis, are very low -- about 5% to 15% -- resulting in estimated fuelwood wastage of 20,000 tonnes per year. However, since majority of the cardamom plantations in Sikkim are small (less than 2 ha) and located in remote hilly areas, the farmers are not able to develop new technology on their own.

Setting 
India, the ancient land of spices is the world's largest producer (54% of world production) of large cardamom. Out of the 4000 tonnes of large cardamom produced every year in the country, Sikkim, prime cardamom territory, contributes about 88%. The large cardamom business in the country is worth Rs 280 million with 25% of the net earnings coming in from exports, which reportedly have trebled since the 1980s. Undoubtedly, then, over the years, both the state and the central governments have been taking a keen interest in upgrading the production of large cardamom for the market, which so long has been done along traditional lines.

The new cardamom dryer, successfully field-tested in nearly all the districts of Sikkim, is now on the verge of commercialization. Overall system design, development, and implementation is being done by TERI. Basic drying parameters were obtained through well-equipped laboratory experiments in the Chemical Engineering Department at the Indian Institute of Technology, Mumbai. The field activities in Sikkim are being executed in collaboration with the Horticulture Department, Government of Sikkim. The project is sponsored by the Indo-Swiss Project Sikkim.

Approach 
TERI's solution to the above problem was to design and develop an appropriate advanced gasifier-based drier system suitable for local field conditions in cardamom plantations. Gasification is a thermo-chemical process in which solid fuel is converted into a more user-friendly and efficient-to-use gaseous form. The gas obtained from the gasification of biomass is called producer gas, which is a mixture of carbon monoxide and hydrogen. The gasifier was of the updraft type, which uses a natural draft of air and requires no electricity. It is a substantial improvement over the traditional bhatti system and has several attractive features:
  • Better conversion (solid to gas) efficiency (above 70%)
  • Controlled combustion
  • Production of clean flue gases
Intervention 
The task was to develop an alternative curing system that would not only improve the quality of cardamom but also be energy efficient.

Considering the extent of use of the bhatti in a year, and the conditions prevailing in hilly sites, the following important points need attention while attempting any alternative design
 
  1. utilizing locally available material to the extent possible
  2. minimizing incremental system cost
Considering these limitations and requirements, the use of a simple low-cost updraft wood gasifier was found to be the most promising option. 

TERI has come up with a designed and advanced gasifier-based dryer with several advantages. The new technique is based on the use of producer gas. Fuelwood is fed from atop a drum-shaped oven, which is ignited from the bottom port and controlled to produce hydrocarbons and other combustible gases within the oven. These gases are then led into a burner inside a dryer and burnt below a mesh on which are spread cardamom capsules.

The use of gaseous fuel gives a better-controlled flame and higher thermal efficiency due to the small, insulated, combustion chamber and the low and controlled air levels. This results in improved production of large cardamom that has an attractive color and greater oil content. Besides, the gasifier-based drying system, made from used oil drums with an insulation lining, is portable and cost-effective and can also be made easily with locally available material. Simple in design, the gasifier can be fabricated in local even workshops even in remote areas.

During the first year of field testing, the gasifier was tested in Kabi in north Sikkim for proof of concept and to obtain useful feedback from users in order to develop a more user-friendly product. Based on the inputs from the user, the system design was improved and four units were extensively field-tested (one each in all the four districts of Sikkim) during the next cardamom harvesting season of 1997. Later on, 15 systems were fabricated in local workshops in Sikkim and installed in north Sikkim during the 1998 season, so as to see the user and local market response to the gasifier system as well as to the improved product obtained using the gasifier system. Farmers could operate the system on their own after some training from TERI staff and the product fetched about 10%-25% price premium. In the last cardamom harvesting season (1999), 30 systems (10 systems per district) were installed in the other three districts of Sikkim, namely east, west and south Sikkim, by providing technical assistance to the Horticulture Department's field staff. In response to inquiries from an NGO of the neighboring country Bhutan, four systems were exported for field-testing.

Way forward 
It is hoped that TERI’s low-cost gasifier-based system for thermal applications will go a long way in checking the rising demand for fuelwood and thereby in arresting deforestation. Moreover, such gasifiers could be put to use in such other agro-based rural industries as ginger drying, cashew processing, and tobacco flue curing with minor modifications.