Thursday, 2 February 2012

Combating Adverse Impacts of Climate Change on Tea Production in Sri Lanka with “No-Regret Strategies”

By  M.A Wijeratne
Senior Research Officer & Officer-in-Charge - Tea Research Institute, Low Country Station, Ratnapura

The human impact on the environment associated with economic growth and development is believed to be a primary cause of global warming.  Such warming has profound impact on living beings and plant life. For instance, photosynthesis, the process by which plants produce organic compounds is largely governed by ambient temperature, carbon dioxide concentration and soil moisture (rainfall). Changes to these environmental factors can  incur profound impact on photosynthesis and in turn, affect crop growth and yield.

Temperature rise, enrichment of ambient carbon dioxide (CO2 ) and  variation of total and pattern of rainfall distribution change crop environments, thus affecting crop growth and yield of non-irrigated plantation crops such as tea. Pest behaviour and disease infestations which are impacted by environmental changes are also closely linked to the productivity of tea land.  Moreover, changing environment can adversely affect product quality. In the recent past, scientists have begun to explore  climate change and assess its impact on crop growth and yield. Fortunately, such studies have paved the way for scientists to identify appropriate measures in which adverse impacts of climate change on agricultural crops such as tea can be mitigated.

Climate Change Impacts on Tea Production 

Tea is Sri Lanka’s topmost agricultural export. It is one of the major plantation crops grown from nearly sea level to around 2200m amsl. The total tea land is estimated to be 200,000 ha of which approximately 60% is managed by smallholders contributing to about 70% of the national production. In 2010, Sri Lanka produced 329 million kg of tea earning an estimated Rs. 155,376 million (Central Bank of Sri Lanka, 2010). The industry is said to employ over 1.5 million people..

Close analysis of climate change impacts on tea production in Sri Lanka shows that tea cultivations at high elevations (>1200 m amsl) are least affected. Rising temperatures are beneficial to tea grown at high elevations as it helps to reach optimum temperature for tea (22 oC). However, it is predicted that rising temperatures and dry weather conditions in warmer regions where the present temperatures are above optimum for tea (low; <600m amsl and mid; 600-1200m amsl elevations) will mask the benefits of CO2 enrichment and limit tea production. In addition,  poor soil conditions and ageing tea bushes make tea lands highly vulnerable to the adverse impacts of climate change.  In order to mitigate such adverse impacts on tea lands in Sri Lanka, it is crucial to adopt good agricultural practices that are also known to be “ no regret strategies”.

Adapting Measures 

Proposed adaptation measures seek to minimize  adverse impacts of extreme (high) temperatures and moisture stress and, ensure that the beneficial effects of CO2 enrichment is properly exploited for sustaining tea yield. They are primarily aimed at improving soil conditions, aerial environment, and adaptability of the crop to stress conditions.


The adoption and long-term implementation of “no-regret strategies” detailed above hinges on two factors; firstly, the profitability of tea cultivation which in turn, limits the capacity of the tea grower (affordability) to effectively adopt such strategies in the field, and secondly, the availability of labour and other resources and required materials  which will facilitate such good agricultural practices that have so far  not been fully adopted in tea lands . It is contended that financial assistance to tea growers will markedly improve the rate of adoption of such “no-regret strategies” whilst minimizing the adverse impacts of climate change.


M.A.Wijeratne is a Senior Research Officer and the Officer-in-Charge of the Tea Research Institute - Low Country Station, Ratnapura. He has published extensively in both local and international journals and books in the areas of tea agronomy and physiology, mechanization of field practices, climate change and land degradation. He was awarded the General Research Committee (GRC) Award of the Sri Lanka Association for the Advancement of Science (SLAAS), and the Science and Technology Award for his outstanding contribution to research in Sri Lanka. He is a member of the Faculty Board of Agriculture, University of Ruhuna and a visiting lecturer of the University of Ruhuna and Uva Wellassa University, Passara.

M.A.Wijeratne is an inventor and has received patent rights for inventing a selective tea harvester, collapsible tea plucking basket, hand pruner and deep fertilizer applicator. He has received two Presidential Awards in Sri Lanka and two Gold Medals from Geneva, Switzerland for his inventions. He has been appointed as an Assistant Commissioner to the Sri Lanka Inventors Commission.

He obtained his BSc in Agriculture from the University of Ruhuna in 1987 and  his PhD in 1994 from the Wye College, University of London, U.K.                                                                                                   


  1. Dear author, there are no enough studies on how climatic changes affect low and up country tea cultivation, and therefore, it may be difficult to comment on the effects of future climatic changes. Secondly, more attention should be paid to the change of microbial communities due to climatic change, because microbs are the key determinants of soil fertility.
    Are there any studies which have quantified the effects of future climatic changes for tea growing areas?

    Thanks and best wishes
    Kuruppuarachchi - Open University of Sri Lanka

  2. Dr. M.A.Wijeratne14 February 2012 at 10:15

    Dear Dr, Kuruppuarachchi,

    Thank you for your keen interest on the subject and comments. We have done detailed study (3 year project) on the impact assessment of climate change on tea production at different tea growing regions in Sri Lanka (Low, mid and up country) with AIACC funds. In this study we have assessed the impact of temperature, rainfall and CO2 variations on tea yield using long term data and results of field experiments. In this analysis , we used 3 most commonly used GCMs and two emission senarios. Depending on the climate change impacts at different regions, we identified most suitable "non-regret strategies" that have proven economic benefits as adaptation measures. However, we were not able to include impacts of microbial changes into this models due to lack of data. The details of this study and more results are given in the two publications given below.

    Wijeratne, M.A., Aanadacumaraswamy, A., Amarathunga, M.K.S.L.D, Janaka Ratnasiri, Basnayake, B.R.S.B. and Kalra, N (2007). Assessment of impact of climate change on productivity of tea (Camellia sinensis L.) plantation in Sri Lanka. J. Natn. Sci. Foundation of Sri Lanka. 35(2): 119-126

    Wijeratne, M.A., Ratnasiri, J and Premathunga, E.W.T.P (2007) Effect of CO2 fertilization on growth and yield of mature tea in the Low country wet zone of Sri Lanka J. Plantation Crops 35 (1): 56-58

  3. What could be the effective means of providing financial assistance to ensure a high rate of adoption of the proposed adaptation measures?

  4. Dear Kanchana,

    Thank you for your comment on the article. The financial assistance can be provided directly to the tea growers (i.e. corporate sector estates managed by plantation companies and smallholders). It could be through a national level project coordinated by the Ministry of Plantation Industries with the asistance of the Tea Research Institute and Tea Smallholdings Development Authority.

    Thank you

  5. Dear Sir,As a undergraduate of Faculty of Agriculture -University of Ruhuna , I am willing to conduct my final year research under the topic "IMPACT OF CLIMATE CHANGE TO SRILANKA SMALL HOLDING'S TEA SECTOR" specially reffering Uva province.So sir you'r article too much help to me to understand the real problems in this field.congrdulations for you'r further exercises.