Tea World

Lesson 6

Winter Dormancy in tea

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What is winter dormancy? Tea bushes in some tea growing countries become dormant   during winter. But in some regions near the equator tea bushes continue to flush throughout the year. The dormancy induced during winter is called the winter dormancy. The length of dormant period increases progressively with the increasing distance from the equator and beyond about 160,the tea bushes show complete dormancy. In N.E. India, we can harvest green leaves only for some 8-9 months and in the rest 3-4 months, there is no crop. However, tea cultivated in those countries located on the equator or near the equator (upto160), there is no dormancy and crops are harvested all the year round. The table below shows how the dormancy period varies with the location of the place.

Mean latitude and approximate period of winter dormancy in some tea growing regions

Country

Mean latitude

Months of winter dormancy

Georgia, Russia

420N

6

Turkey

410N

6

Iran

370N

5-6

North East India

260N

3-4

South India

110n

0

Sri Lanka

60N

0

Kenya

0

0

Indonesia

50S

0

New Guinea

60S

0

Malawi

160S

0

Maritius

200S

2-3

Argentina

300S

3-4

What is the reason of winter dormancy?

In the past, we believed that low temperature was responsible for winter dormancy at higher altitudes. However, low temperature is not the sole cause. Soil-water stress and nutrition are also ruled out as the cause of winter dormancy.Because even with ample supply of water and nutrient, tea bushes fail to flush during winter. Then what is the cause? We know that long and short days regulate plant growth by altering the levels of endogenous growth regulators. Tea plant is sensitive to photoperiods. When the day length during winter falls below11 hours 15 minutes for at least six weeks, tea bushes pass through a period of complete winter dormancy. It is now thought that winter dormancy in tea is a matter of short day length acting through the internal plant growth regulators. Short days alter the balance of endogenous regulators in favour of dormancy and long days in favour of growth.

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