Shade trees line a tea garden. These trees have been found to be beneficial to the health and productivity of tea bushes. Picture courtesy: www.teaclimate.com
Guwahati, Nov. 11: Precipitation has been identified as a key factor affecting tea yield in Assam - a new research has shown.
"Preliminary findings of a project indicate that changes in precipitation are affecting yields due to water restrictions, rather than temperature. If rainfall is adequate and well distributed, higher temperatures will not restrict yield. But if precipitation is restricted, even optimum temperature cannot sustain the yield," R.M. Bhagat, deputy director at Tocklai Tea Research Institute, told The Telegraph.
The results were revealed in the working group report on climate change at the intersessional meeting of FAO Intergovernmental Group on Tea held in Milan, Italy, last month. Bhagat was present in the meeting.
The study - Climate-smartening Assam's Tea Plantation Landscapes: Defining Socio-ecological 'Safe Spaces' for Future Sustainability - investigates the extent to which climate variability is influencing tea yield in a high quality producing region of the world as India, which is the world's second largest producer of tea.
The UK-India Education Research Initiative and the department of science and technology, government of India, are funding the project. The work was carried out at Tocklai Tea Research Institute.
Tea is a rain-fed perennial crop and one of the most important beverages in the world, with international trade being the largest in value among tropical and subtropical crops. Assam is one of the most important tea-producing regions of the world, contributing 17 per cent to global tea production and more than 50 per cent to the Indian market annually.
Studies were conducted in a few tea gardens on the north bank of the Brahmaputra, one of the four major tea-growing areas of the world. Multiple climate conditions were used in the analysis, including 30 precipitation conditions and 110 temperature conditions to capture the effect of climate intensity.
The initial results indicate that continuous periods of zero precipitation are associated with reduced yield. Total precipitation has a positive association with tea yield from July to September.
"The preliminary results from the north bank area indicated that in this area, precipitation might be the predominant driving factor. Such observations might be reflective of a good monsoon year resulting in higher yield, and a more variable monsoon year resulting in lower yield," the report said.
The north bank tea-growing region of Assam is situated within a rain shadow area of the state, and as such there is an expectation that precipitation would have a potentially greater influence on tea productivity than temperature.
Climate change is taking a heavy toll on the tea sector this year and Assam's September crop is down by 0.87 million kg compared to last year.
Model studies indicate that tea yields in the Northeast are expected to decline by up to 40 per cent by 2050. As yield is directly associated with revenue, changing climate is likely to impact economic structures of those reliant on tea, particularly the small growers, given their increased vulnerability to changes in the system.
A web-enabled decision support system is under development to provide better-informed climate advisory services under the project.
Detailed findings of the project, which studied 80 gardens, will be revealed next month at an international conference in the US.