By Mark Tully Former BBC India correspondent

The north-eastern Indian state of Assam is renowned for its tea - the backbone of its economy. The traditions of the old estates, including hand-picking, make the tea expensive. But any drop in quality would undermine the Assam brand.

Spending the night in an old fashioned British Raj bungalow on a tea estate in Assam, I was awoken at six in the morning by a siren.

For more than 1,000 men and women this was the alarm call which got them out of bed to prepare for eight hours plucking tea, planting new tea bushes, weeding, digging ditches, or doing any of the other tasks required to produce high quality tea.

The siren also summoned the planters who manage the estate to a meeting with the senior manager at which he allotted them their work for the day.

Assam tea estates look like a vast billiard table cloth - acre after acre of squat green tea bushes huddled together and kept flat by regular plucking.

The tea estate I stayed on was run in the military manner that my autocratic uncle used to manage his estate during the British Raj.

The planters attending the early morning meeting are the officers. They still wear the traditional uniform - shorts and long socks.

The senior manager is the commanding officer. He lives in a bungalow, the splendour of which is a symbol of his authority.

The officers' mess is the local planter's club, founded by the British. Twirling a white, magnificent, military moustache, Deo Raj, the soldierly senior adviser to the company which owns the tea estate said to me: "This regimental system worked for the British and it has worked throughout my 50 years in tea."

The soldiers, the workers, live on the estate in what have always been known as "labour lines". The early British planters could not find workers locally so labour contractors collected not just men, but women and children too, from distant parts of India and sent them on boats up the Brahmaputra river which flows through Assam.

The conditions on the long journey were so hazardous that it was not uncommon for half the workers to die before they reached the estates.

Many of today's tea plantation workers are descendants of the people who somehow survived that journey.

Deo Raj says workers are now "looked after from womb to tomb". Apart from their wages agreed by the government - and their homes - they get free rations, wood for cooking and electricity. There is a hospital and a school on the estate too.

This old-fashioned, paternalistic style of management makes workers very expensive but Deo Raj opposes reducing their number by mechanising the tea plucking.

Watching women nimbly plucking the bright green, new leaves off the top of tea bushes, he explained that machines cannot differentiate between stalks and leaves, and went on to say: "A mixture of leaves and stalks, which is what you will get with a machine, does not make good tea."

But now the Tea Estates that Deo Raj supervises may be forced to mechanise because there is a shortage of people willing to pluck tea and maintain the bushes.

He puts this down to the low social status of tea garden work and the survival of another tradition, the designation of the workers as "coolies".

Deo Raj says: "The young people tell us that they may have been born as coolies but they are not prepared to be known as that for the rest of their lives."

However, in an other garden, workers told me that the work provided under the government's comparatively new unemployment scheme was attracting tea garden labour. When I asked why, I was told: "On that scheme you are meant to work but nobody makes sure that you do. Here, they watch you all the time."

The ever-increasing number of small-holders who grow tea represent another threat to the quality of Assam tea. The small-holders beat the estates on price because they do not have the same high costs. The problem is that they do not match the estates' quality.

There are also estates which do not maintain the quality of their tea. Deo Raj insists that no bush on an estate he supervises should be more than 40 years old because after that the quantity and quality of the leaf declines.

Nevertheless, uprooting and replanting is very expensive, so a number of estate owners retain bushes as long as they produce some leaf, no matter what its quality may be.

Poor quality tea undermines the Assam brand, and it is only because of the brand's reputation for quality that the tea competes with the leaf produced in Kenya and Vietnam where costs are much lower.

So protecting the brand is vital for Indian tea exports, which have fallen by 12% over the last five years.

Deo Raj says: "You can only maintain quality if you manage tea estates as I have seen them managed for the last 50 years."

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