Climate Change Hits Assam Tea

The flavour has changed from what it was before. The creamy and strong flavor is no more. It has been revealed that the changes have already been observed everywhere in the Indian tea industry and scientifically it is established that these are gravely attributed to excessive use of pesticides attributed to climate change. Other factors like cultivation methods might also be partly responsible. Studies by  scientists  including Toklai Experimental Station (TES) at Jorhat, Assam has also revealed these  changes.

Excessive pesticide residues in tea continue to be a concern among exporters. These pesticides used in tea plants generally fall in two groups: organochlorines organophosphates and pyrethrins. The chemicals used in tea cultivation are dicofol, endosulfan, ethion, fenzaquin and parquet among others. But all tea producing countries do not have the same standard regarding use of pesticides. The pesticide levels in tea measured from some countries are not within acceptable levels.

Assam tea is acclaimed worldwide for its distinctive taste, and if this is affected, it could spell doom for exports in the long run. According to TAI estimates, the average price realization from exports have been quite discouraging in recent years due to major improvement in production by Sri Lanka and Kenya, India’s two major rivals in the export market.

Scientists from TES, the oldest tea research station in the world, said rainfall and minimum temperature were two of the most important factors affecting both quality and quantity of harvests. The decline has been taking place although there has been an increase in the area of tea cultivation as new gardens have come up, and many gardens have added new areas for tea plantation. This is an indication of the seriousness of the threat. A rise in temperature and change in rainfall pattern are threatening the production and quality of India’s Tea.

Rainfall in North-east India has dropped by more than one-fifth in the past 60 years and the minimum temperature has increased by 1.8 degrees to 67.1 Fahrenheit. A rise in temperature and change in rainfall pattern are threatening the production and quality of Indian Tea. The average rainfall in NE India ranges from 2000-4000 mm. However more than total amount the distribution of rainfall matters a lot for sustained high yield of tea throughout the season. In the NE India, the rainfall distribution is not even. The excess rainfall in the monsoon months of June – September causes drainage problems.

The average monthly rainfall during November to March is less than the evaporation loss and the resulting soil moisture deficient affect tea bushes. When this dry spell persists for a longer period, tea plants suffer heavily and crop goes down in spite of having sufficient
rainfall in the monsoon.

A study earlier conducted by the TES had found that the average minimum temperature in Assam had risen by 1 degree Celsius in last 90 years, besides the region losing around 200 mm rainfall because of climatic changes. Temperature affects tea yield by influencing rate of photosynthesis and controlling growth and dormancy. In general, the ambient temperature with 13 degree C and 28-32 degree C is conductive for growth of tea. Maximum ambient temperature above 32 degree C is unfavourable for optimum photosynthesis more so if it is accompanied by low humidity. In the tea belts of the region the average winter minimum temperature (Dec- Feb) remains below 12 degree and there is hardly any growth during this period.

About 850 tea gardens in Assam produce 55 per cent of India’s tea, but crop yield are decreasing and amid fears of a co relation with environmental change. Assam is the largest tea producing state of India and accounts for around 55 per cent of total tea produced in the country. Though Assam witnessed a bumper tea production in 2009, thus bringing the industry out of 10 years of recession, production took a hit last year due to excessive rainfall. From 499 million kg in 2009, the figure dropped to 480 million kg in 2010 in Assam. Total tea production in India in 2010 was 966 million kg.According to Tea Board estimate Assam produced 512,000 tonnes of tea in 2007. By 2008 this had declined to 487,000 tones, with estimated production in 2009 down again to 445,000.

Fortunately the output in Assam, the largest tea-producing state, was up 5 per cent to 607.83 million kg in the April-December period of 2013-14, from 577.13 million kg in the year-ago period. Of course this has happened on account of vast cultivation area extension by small tea-growers. Climate change makes bound and unavoidable the profuse uses of
fertilizers and pesticides in tea cultivation which degrades both quality and quantity of Assam and Darjeeling tea, a section of tea cultivators and experts said. A steady decline or an almost stagnant picture shown in tea production has been blamed on climate change.

What’s really scary is that this change in climate seems to be affecting the tea’s flavour. Researchers from TES said that some 41 species of mirids in the genus Helopeltis have so far been described in the world and most of them in India. In recent years, two species of Helopeltis, H. schutedeni Reuter (Hemipetra: Miridae) and as earlier predicted, H. thievora waterhouse, have become the greatest enemies of tea planters in India or Asia I but in Africa causing 55% and 11% to 100% crop loss, respectively. Some bugs are transforming themselves into super bugs, thereby making the common pesticides worthless in the tea gardens of Assam.

Helopeltis (Tea mosquito bug) and looper caterpillar is gradually attaining resistance against common pesticides used in our tea gardens. Helopeltis has been keeping the tea growers scary for the past several years. Constant use of same kind of same kind of pesticides is leading to the transformation of these insects into super bugs much to the anxiety of the tea planters and the scientists as well.

It is almost impossible for Assam tea to survive without use of these chemicals because of the sub-tropical climatic condition in the state where the use of these chemicals are necessary for pest control. The tea industry in India is turning up towards domestic market rather than follow a stricter tea standard. What is alarming is that tea growers are still using harmful chemicals like HCH, DDT, Dicofol, Fenvalerate, Methamidophos, Alphamethrin and Acephate.

A cup of tea that cheers can also be an important route of human exposure to pesticide residues. It is important to evaluate the percent transfer of pesticide residue from dried (made) tea to tea infusion, as tea is subjected to an infusion process prior to human

Chandan Kumar Duarah

First published  in Eurasia Review


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