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