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The results of four years of drought in water-rich Yunnan province China in 2021.
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This basic mechanization in Kenya replaces up to 20 pluckers, mainly women.
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High volume tea harvester: ideal for large farms, flat terrain, lower quality tea.
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Tea plantations on the valley slops north of Muyu, a town in the Shennongjia Forestry District of Hubei province, China.
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Assam farm drought 2013.
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Blades cut whatever they come in contact with and pluckers then select the best leaf.
El Niños, El Niñas, droughts, more droughts and deluges: is the tea tree under siege around the world? Although droughts are bad for yields, they often improve the quality of some teas. Also, the amazing tea plant — surviving now for hundreds of millenium — is packed with genetic defenses against moisture-deficiency.
Drought is the single main constraint in any given year on the tea yields. It is a byproduct of many external forces, most especially seasonal rainfall. It’s situational, with microclimates affecting frequency, severity, and impact. It affects young plants more than mature ones. In the very short-term, drought improves the quality of some teas, intensifying aromas and adding a fuller flavor, but with loss of production. It often results in a sudden and short price increase in international markets due to supply shortage. That can disguise the longer-term global which are widespread and have substantial economic and social impact.
In Tanzania, crop yield in 1992 fell by a third from 5,900 kilograms per hectare –a huge blow to jobs and farming communities – to 3,900, For young plants, the drop was almost 60%, from 4,720 kg/ha to 1,960. The figures are substantial in themselves but crippling for a nation like Tanzania, one of the world’s 50 least developed countries, which has been targeting tea for its foreign exchange base and job growth.
Kenya, Sri Lanka, and India’s Assam face the same disruptive menace. Kenya reports that the “oxidative stress” from drought reduced yield by 14-19% and increased plant fatality by 6-19%. After a poor year in 2020, with a large loss in production from Covid-19 restrictions and lockdowns, Assam predicted a bumper crop. Instead, policy makers see the outlook as bleak due to a severe drought that is the direct result of its opposite: rainfall in the form of a severe hailstorm.
In Sri Lanka, struggling for decades to improve productivity, with the highest harvesting costs of major exporting nations, 1992 saw a drop of 26% in output. This began a long-term slide that lost the nation its position as the world’s leading exporter to Kenya. Seasonal droughts have been recurrent, with significant regional differences. In 2016, some of these saw a 60-70% drop in seasonal rainfall. Soil with poor nutrients needs more rainfall, with its water holding capacity key. Heavy rainfall reduces sunshine. The pattern continues. The Planter Association of Ceylon forecasts a 40% drop in production in 2021 from a four-month drought.
The relationship between rainfall and drought is direct, with rain the causal factor and drought the consequence. The major force at work globally is El Niño, basically a giant puddle that forms annually in the eastern Pacific Ocean and expands to create a global chain reaction of weather effects. The 2015 El Niño was a record and is blamed for the mass dying off of corals worldwide, for example. Commentators uniformly see it as getting worse. Asian farming depends on the El Niño patterns. Two-thirds of the land lacks irrigation and is completely dependent on rainfall. A 5% drop in monsoon rains signals a coming drought period and 10% marks it officially. There is no shortage of water across tea growing nations but these disruptions change its distribution. No fix has been found to avert the resulting droughts.
Yunnan: where superb teas grow – or die
Yunnan provides an example of just how far-reaching a general long-term shift in rainfall patterns and consequent moisture loss can be. It produces many of the world’s most noted teas, including puehrs, even though it is marked by 50 drought years in the past 60. Farmers adapt to the localized seasonal shifts in rainfall and water runoff created by its unique mountain plateaus and monsoons. But their livelihood can be badly damaged by a severe and sustained drought, such as that of 2019. This slowed the growth of new leaves, delaying the spring harvesting by two weeks, a critical disruption of both output and quality. One smallholder reported the impacts on his family operation: a reduction from 600 to 360 kilograms of leaf for one of the highest priced teas on the market, puehr, that sells for an average $436 per kilo. Production costs are mainly fixed so that the reduction in volume disproportionally erodes margins.
That’s the short-term effect. Many trees had to be uprooted. The “pitiful”’ ones that survive will need 3-5 years to recover fully. Many of the lost trees were 60 years old. The replacement expenses are an expensive capital drain along with the loss of productivity. In general, the drought means a loss of quality from damage to the spring harvest when the plant nutrients are at their richest and freshest. Prices increase: fine puehrs are scarce at any time and the final product rests on the processing of wild tree “maocha.” Lose that and the most distinctive features of puehr are eroded.
In 2019, one of the six major mountain areas that produced puehr experienced its hottest temperatures and lowest rainfall in decades. Spring output halved. The slow growth of new leaves led to a critical two-week delay in harvesting..
A smallholder summarized the 2019 effects on his family operation. It “depends wholly on tea for survival.” He grosses around US$30,000 in a typical year. In this now typically atypical year, his production halved. This means the grower lost half his revenues but most of his costs remain: maintenance, planting, plucking, and fertilizer. His plants are now badly damaged and it may take three to five years to make a full recovery – if they survive. They are in “pitiful” condition. Many are 60 years old and have remained productive through the droughts of the 2000s. Now, they have had to be pulled up and burned. The result is a poorer tea at a higher price.
Yunnan has plenty of water but its special geography that produces special tea relies on a seasonal pattern of little rain in winter and early spring and intense daily downfall in summer and fall. It is directedly affected by the strongest of the East Asian and Indian monsoons that fall in torrents. Seasonal climate and even daily weather are mainly driven by the interaction of warm and cold air. Yunnan’s mountains may block the flows. The westerly high-altitude regions are warm and dry and their strong ultraviolet rays increase water evaporation. When there’s not a balance between water supply, storage and distribution, evaporation means menace. Menghai county in Yunnan illustrates the effects of weather and water. In 2020, the average rainfall in 2020 between January and March was almost 80% less than for the same period the year before, with severe resulting droughts. It received its first rain in mid-April, but within a week forecasters predicted even more “orange index” level drought peaking at the end of the month. Tea buds germinated 10-14 days later than in 2019. The plucking cycle was 30 days behind and one-third shorter.
The molecular armory of tea
The tea plant is packed with defenses against moisture-deficiency. It is best thought of as a massive store of genetic and molecular compounds that are put to work by an immensely complex and dynamic network whose pathways connect them as needed. Keep in mind that the tea plant has no interest in you. Its “genome” – the complete embodiment of its DNA and chromosome sequences and codes that define every aspect of it as a living organism – is Darwinian in nature.
This has preserved the tea plant’s survival for an estimated 400,000 to maybe even 1,500,000 years. Drought is commonplace in that history. The main efforts to extend its adaptability focus on exploiting this genetic resource base. The main area of innovation has long been clonal teas, the equivalent of cross-breeding cultivars – varieties within a shared genetic heritage. There has been a flow of development of drought-resistant clonals, but new ones take 10-25 years from parent candidate identification, nursery testing and propagation, field trials and planting, and productive yield. The emerging developments extend this to the genome itself and to molecular engineering. Management methods help improved short-term remediation, most notably fertigation, highly targeted and timed irrigation plus fertilizer feed.
At the start of drought conditions, the plant’s chemistry is marshalled to adapt. It accumulates soluble sugars that improve its ability to retain water, for instance. But over time if the root system and nutrients cannot maintain a water absorption balance, the leaves begin to wilt then scorch and fall off. After the drought, damaged bushes must be pruned and retrimmed, and nutrients and fertilizer added to restore soil vitality.
The plant puts to work around a known 100 amino acids, 30,000 protein-coding genes, 300 MiRNA (micro RNA) sequences, to adjust leaf size and structure, tailor the root system, and allocate stimulant and inhibitory nutrients. There are probably 750 or so unexplored compounds. Much of the balancing affects flavor and taste. Drought response adjusts the soothing theanine and the many anti-oxidants that are believed to generate health benefits for humans. Caffeine levels are generally not affected. Their Darwinian role is to dissuade and overdose pests.
Clonal development has been promising. Now, molecular biology is in early research and piloting. CRISPR – “genetic scissors” – will permit tweaking, adding to, or blocking the structure and interactions of the genome. There’s a risk that the narrowing down of genetic diversity will add new risks, a commonplace concern with GM crops –genetically modified. Agroforestry and biomanagement methods add some buffers to drought: reforestation to help plant and water collection, soil care, replanting, and organic fertilizers. Farmer education helps disseminate lessons and techniques. Whether they are enough to provide a bulwark against drought as the norm is questionable.
Drought kills plants and crops. The challenge is to mitigate it from killing entire plantations and tea regions, vulnerable economies, and even the economies of tea-dependent nations.