Areas of Research

Plant Improvement

Tea plant improvement is one of the most important areas of research for Tocklai Tea Research Institute. For the growth and development of Indian tea industry, Tocklai has been producing a large number of cultivars which are being used by the tea plantations for a long time. The popularity of clones gained momentum in tea cultivation since the standardization of vegetative propagation and release of the three clones, TV1, TV2 and TV3, by Tocklai in 1949. Since then Tocklai has been continuing its efforts to develop improved planting materials through selection and breeding. Till date Tocklai has released 31 TV clones for commercial cultivation, besides 153 garden series clones. Moreover, another 27 clones were released exclusively for planting in Darjeeling hills. Thus, till today, Tocklai has released 211 clones and 14 seed varieties to the tea industry for commercial planting. Collection, conservation and utilization of tea genotypes or germplasms have been continuing as an essential activity of Tocklai since its inception. As a result, Tocklai has a large germplasm collection which is utilized for continuous tea breeding activities.


Biotechnological research on tea is rather young, having started in 1980. Work has been done on micropropagation, somatic embryogenesis, protoplast culture, anther culture etc. Development of different types of molecular markers and characterization of the large germplasm collection, using DNA finger printing techniques, have been successfully done. Gene expression profiling and identification of candidate genes have also been carried out.


Through a large number of experiments, Tocklai has determined the optimum plant population per hectare and also standardized the preplanting operations. Bringing up of young tea from planting to the first frame formation pruning is another area where clear-cut recommendations have been released to the tea industry. The productivity of tea gardens is closely related to the efficient and complete harvesting of pluckable shoots and, therefore, harvesting assumes paramount significance in the economy of estates. Harvesting is a highly labour intensive operation and 60-70% of the workforce in an estate is employed for this work. Hand plucking is the norm in the gardens of north east India. But the shortage of experienced workers during the high cropping season is adversely affecting the harvesting operations. To overcome this, Tocklai is conducting experiments on mechanization of field operations like pruning and harvesting. Our initial studies have shown that pruning machines and harvesting machines can be successfully employed in our tea gardens. This will improve the productivity of the estates and improve the earnings of the workers. In north east India, bushes remain in a dormant stage for about three months in the winter period. Tocklai has studied in detail the physiology of bushes in relation to winter dormancy, photosynthesis and tea shoot development. Consequently, we could give firm recommendations to the tea industry on pruning and harvesting. Nutrients like nitrogen, potassium, phosphorus, sulphur and zinc play a major role in the health and productivity of bushes. Tocklai has recently developed an Integrated Nutrient Management system involving the use of organic manures, vermicompost, biofertilizers and synthetic fertilizers. Our recent experiments have shown that the use of synthetic fertilizers can be reduced by 20-25%, if we use organic manures and biofertilizers in sufficient quantities.

Organic Tea

Organic tea is yet another area in which Tocklai has been conducting long term experiments. Through a series of investigations, we have developed a package of practices for organic tea in north east India and this package is now available to the tea gardens. Vermiculture is a subject of contemporary interest and here again Tocklai has done research and published the method for vermicomposting in tea gardens.

Water Management

Water management is a critical area of operation in the estates. In this context, it would not be out of place to mention the commendable work done by Tocklai on drainage. While flooding and waterlogging are the major problems in the Brahmaputra valley, soil erosion and land slides are the main problems in Barak valley and Darjeeling. In the plantations located at the Himalayan foot hills and Terai area, flooding, gully formation and river erosion are the major causes of concern. Tocklai has used remote sensing technique on a GIS platform for covering large plantation areas of major watershed basin.

Tea Soils

Tea soils have undergone considerable degradation over the years. The benefits of soil rehabilitation have been studied by Tocklai. It has been proved that soil rehabilitation increases organic matter and improves soil structure. The benefits of soil rehabilitation are more pronounced in the heavy textured soils.

Climate Research

To develop a climate resilient tea production system, a project was initiated at Tocklai to study the impact, vulnerability and adaptation of tea to climate change. This is a part of the network project launched by ICAR all over India to study the overall impact, vulnerability and adaptation of Indian Agriculture to climate change. Major findings of the project so far are :

  • Long-term weather data records of TRA suggest decline in rainfall and an 5 increase in
  • There is an increase in the frequency of extreme events (e.g. high rainfall resulting in floods and low rainfall resulting in drought like situations).
  • Extreme weather events are found to trigger some biotic stresses (e.g. increased disease/pest attack) because conditions are becoming conducive to such
  • Initial results of controlled field experiments have indicated that organic tea or organically integrated tea production system is more climate resilient than the conventional

A new facility of Open Top Chambers (OTC) has been commissioned at Tocklai to study the growth and behavior of tea plants at elevated carbon dioxide and temperature situations. All the TRA-released clones are being subjected to elevated CO2 and temperature conditions, besides creating artificial water stress (both high and low) conditions in the OTCs. Individual and combined stress of all the components of abiotic stress will be given and the physiological changes, production potential as well as quality of tea will be monitored. The level of stress (e.g. CO2 and temperature elevation) will be created based on the future climate scenarios to be developed using PRECIS (providing regional climates for impact studies) model developed at the Hadley Centre, UK. Testing all the clones under these future climate scenarios would allow us to conclude the vulnerability of the clones and to figure out as to which of the clones will survive and produce economically with reasonable quality. Further, it is being speculated that tea, being a C3 plant, may show higher productivity at elevated CO2 conditions, but it is not yet known as to how the plant will behave when CO2 and temperature will shoot up and water stocks will be either limiting or excess in soil and other meteorological parameters will be extreme. This project will ultimately answer some of these questions and would try to look for adaptive measures.

Pest and Desease Management

Tea plantations in north east India are severely affected by several pests and diseases. Tea mosquito bug, loopers, slug caterpillars, thrips, greenflies and termites are the major pests of tea while black rot, blister blight and red rust are the important diseases. Tocklai has recommended certain pesticides for the control of pests but the recent trend is to reduce the use of synthetic pesticides and to move towards the use of biological control agents, behaviour 6 modifying chemicals, and use of plant origin pesticides. Tocklai has released certain biological control agents and fungal antagonists on a commercial scale for the control for pests and diseases. These are being extensively used by the gardens. More research is being done on the sex pheromones of tea mosquito and loopers. Biological control agents of termites and loopers are being studied and these will become available shortly. Plant growth promoting rhizobacteria is another subject of research. The use of these beneficial microbes will enhance the resistance of tea plants against pests and increase the plants’ productivity. Tocklai has achieved some useful results which are being tested on a commercial scale. Estates will be using only those pesticides which are recommended by Tocklai based on extensive field testing and residue studies. It has been proved that the tea brew contains very little of residues and, therefore, safe to the consumers.


Tocklai has conducted detailed investigations on the biochemistry of tea and documented the physico-chemical changes taking place during manufacturing. Tocklai has also developed machinery for tea processing. While India adheres to the global standard of ISO 3720 for tea, many countries are yet to adopt this standard.

Analytical Services

The Analytical Services department undertakes analysis of soils, soil amendments and other agricultural inputs like synthetic fertilizers, organic manures, micronutrients, pesticide residues and heavy metals. Samples received from tea estates are promptly analysed and reports sent enabling the estates to carry out the agricultural operations in time. Analytical laboratory is accredited by National Accreditation Bureau for Testing and Calibrating Laboratories (NABL) under ISO 17025.

Tea Processing and Manufacturing

Tocklai puts a lot of thrust on the improvement of tea processing techniques to boost the quality of produced tea. It achieves this through experiments on packaging and storage of tea, application of various technologies for the optimisation of space, power and labour in factories, tasting of commercial tea samples, testing of commercial products used in factories and processing and assessment of experimental tea samples. Tocklai also assumes an advisory role for the Tea Industry on factory layout, design specifications of machinery and other aspects of tea processing. The Model Tea Factory (MTF), located within the premises of Tocklai, is a complete representative black tea manufacturing unit, equipped with all the facilities and flexibilities of a commercial factory. It houses state-of-the-art tea processing machines, allowing the highest level of mechanisation. Each of these machines has been augmented with various sensors and additional control features. Advanced networking technology, along with computerbased distributed data acquisition and measurement systems, have been used for online monitoring and real-time data logging.
List of machines designed/developed by Tocklai and used by the industry-

  • Rotorvane
  • Continuous Tray Drier
  • Rotorvane Attachment
  • Rotorvane Cone Attachment
  • Rotorvane Improved
  • Borbora Continuous Leaf Conditioner
  • Baruah Continuous Roller
  • Baruah Continuous Roller Improved
  • Tea Breaker Cum Stalk Separator
  • Green leaf Storage System
  • Electronic Monitoring and Control System for Withering.
  • Modified Open Trough for Withering.
  • Modified Rolling Table

List of process modifications developed by Tocklai for improvement of quality
  • Modified process for CTC manufacturing
  • Modified Rolling process for Orthodox manufacturing
  • Application of food grade additive in pre and post harvest treatment
  • Modified process of withering for enhancement of brightness and briskness