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Crop Cultivation Guidence

Plantation Crops : Tea

Introduction

The oldest known beverage, tea is native of China in South East Asia. It was known to the Chinese as early as 2737BC, but attained the status of a popular drink in England in 1664 AD. India is the largest producer, consumer and exporter in tea industry.
Tea belongs to the genus Camellia and family Camelliaceae.

Tea Cultivation Guidence

The original species, which produces tea, were C.assamica (Assam jats), C.sinensis (China jats) and their natural hybrid, C.assamica subspecies lasiocalyx (Indo China or cambod type). Being a highly cross pollinated crop, the present day seedling populations are mixture of both the above two species, however, from their major share of characters – Assam or China type can be distinguished by the following characters.

Assam China
It is a tree It is a shrub
Few robust branches Branches abundant and whippy
Large, glossy leaves Small leathery leaves.
Light to medium green Dark green colour
High yield and medium quality Low yield but good quality
Susceptible to drought and frost Hardy and resistant
Sparse flowering Profuse flowering

Morphologically, tea is an evergreen shrub or tree, leaves are simple, alternate, serrate, flowere bisexual, with superior ovary, fruit is a capsule.

Varieties

Clonal selection from seedling population was taken up by UPASI, Tea Scientific Department, Cinchona and also by other Tea Research Institutes. UPASI has so far released 27 clones. Certain outstanding clones released by other Institutes are also used in South India.

Clone Characters
URASI-2 (Jayaram) An average yielding clone, suitable for all elevations, tolerant to drought and wind.
URASI-3 (Sundaram) Very high yielding and quality clone.
URASI-6 (Brooklands) Fares well at mid and higher elevations.
URASI-8 (Golconda) High yielding, suitable for all elevations.
URASI-9 (Athrey) High yielding, fairly tolerant to drought, Can withstand slightly high pH.
URASI-10 (Pandian) Hardy clone, resistant to drought and wind; suitable for high elevation.
URASI-14 (Singara) Quality clone, suitable for higher elevations.
URASI-17 A high yielding clone.
TRI-2024 (Sri Lanka) High yielding clone.
URASI-2025 (Sri Lanka) Average yielding;hardy clone.

Climate and soil

Tea is exacting in its climatic requirements. The temperature may vary from 16 to 320C and annual rainfall should be 125 to 150 cm, which is well distributed over 8-9 months in a year. The atmospheric humidity should be always around 80% during most of the time. Very dry atmosphere is not congenial for tea. It is grown in plains in North Eastern States but in South India, it is grown in hill ranges from 600 to 2200 m above M.S.L.

Tea is a calcifuge crop requiring comparatively low amounts of calcium but high quantities of potassium and silicon. They can be grown in lateritic, alluvial and peaty soils. Optimum pH range is 4.5 to 5.0 and soil depth should be 1.0 to 1.5m.

Propagation

Tea can be propagated by seed and by cuttings. Seeds collected from the fruits of seed baries are soaked in water and only heavy seeds, which sink, are alone used for sowing in beds. Germination occurs in 20 to 30 days. At that stage they are carefully lifted and transplanted in polythene sleeves. They will be ready for planting in 9 months.

Vegetative propagation

The site for the nursery can be selected in a flat land or gentle slope, near to a perennial water source and easily accessible by road. It should have a good drainage and should be protected from wind, frost and wild animals etc. approximately, 0.15 ha nursery area is required to produce 1.25 lakhs cuttings. Nursery area is to be provided with overhead shade by erecting concrete or stone pillars at a spacing of 3x3m and spread with 6mm2 mesh double strand coirmat which provides about 67% shade.

The cuttings for rooting are collected from mother bushes, which are well maintained near the nursery area. Such mother bushes are pruned well in advance to induce juvenile shoots. These juvenile shoots are collected in the morning hours and 3cm long cutting each with a healthy mother leaf and an active axillary bud is prepared. Cuttings from top tender and bottom brown wood should be avoided. These cuttings are planted in polythene bags (30cmx10cmx150 gauge), filled with growing medium (Jungle soil: river sand 3:1) in the bottom and rooting medium (Red/subsoil:sand 1:1) in the top 8-10cm. The soil used for rooting media should have an optimum pH range of 4.8 to 5.0, if high, i.e., 5.1 to 5.5, or 5.6 to 6.0, it must be drenched with 1 or 2% aluminum sulphate solution respectively @ 1 litre per cubic foot of soil. This treatment should follow with drenching of twice the volume of plain water to wash excess aluminum sulphate. The cuttings are carefully planted at the centre of the bags in such a way that the petiole should not touch the soil and then they are watered. These bags are then covered with polythene sheets over the G.I. wire arhes and the sides are tugged well to preserve moisture content. Callusing starts in 4-6 weeks and rooting occurs in 10 to 12 weeks. When 80% of the cuttings have rooted, the tents are opened in stages and the overhead shade is gradually reduced to harden the plants.

Planting

The land is cleared of the roots of the fallen trees and drains are taken at suitable intervals depending upon the slope to conserve the soil. In the olden days, up and down system of planting at 1.2x1.2m are followed. Presently, contour planting either in a single hedge or double hedge system is followed.

Sr. No. Type Spacing Population/ha.
1. Up and down 1.2 x 1.2m 6,800
2. Contour planting single hedge. 1.2 x 0.75m 10,800
3. Contour planting double hedge. 1.35 x 0.75 x 0.75m 13,200

The last method has many advantages over the first two viz., early and high yield, better soil conservation, less weed growth in the hedge and efficient cultural practices. Planting season normally coincides with June/July and September/October for SouthWest monsoon and North East monsoon areas. Pits of 30x30x45cm size are dug and plants of 12-15 months old are planted by removing the polythene sleeves. Immediate after planting, plants are staked to prevent wind damage.

After care

Immediately after planting, the soil surface around the plants should be mulched, usually cutgrasses of gautemala are employed for this purpose. About 25 tonnes of grass is required to mulch one hectare. Care must be taken to keep the mulch materials away from the collar region last they may cause collar diseases. If there is a dry weather, mud tubes or etah tubes may be buried 15cm deep near the plant in a slanting position and one litre of water per plant may be poured or injected at weekly intervals. This subsoil irrigation helps to minimise the causality besides encourages developing deeper roots.

Shade management
Tea requires filtered shade and if it is exposed to direct sun, its growth is affected. Shade is hence essential and beneficial to tea as

  • It regulates the temperature.
  • It minimises the effects of drought and radiation injury.
  • It increases the soil fertility
  • It helps in recycling of nutrients.
  • It helps in getting even distribution of crop.
  • It serves as windbreak.
  • It reduces the incidences of pests.
  • It generates additional income by way of timber and fuel.
The desirable characters of a good shade tree like
  • It must be an evergreen tree, easy to propagate having quick growing and deep rooted characters.
  • It provides filtered shade and withstands frequent lopping.
  • It tolerates wind and frost.
  • It does not have allopathic effect.
  • It has commercial timber value also.

Weed control

Weeds will be a problem in young and pruned fields. Manual weeding is never recommended in tea lest more soil erosion and damage to surface roots and collar regions. Therefore, the following chemical weed control is alone recommended in tea.

Type of weeds Herbicides Dosage
Dicots Paraquat (gramoxone) 1.12 lit. /ha.
Dicots Sodium salt of 2,4-D (Fernoxone) 1.4 kg. /ha.
Grasses 2,2-Dichloro propionic acid (Dalapon) 5.6 kg. /ha.
  Glyphosate 2.3 lit. /ha.

Training and Pruning

In the young tea, when it has established well, centering i.e. removing the growing point leaving 8 to 10 mature leaves from the bottom, is done to induce secondaries. When the secondaries reach more than 60 cm, they are tipped at 50-55 cm height by removing 3 to 4 leaves and bud to induce tertiaries. Therefore, plucking at mother leaf stage is continued for better frame development. It takes nearly 18 to 20 months from planting to reach regular plucking field stage.

Pruning is done in tea

  • to maintain to convenient height for plucking
  • to induce more vegetative growth
  • to remove dead and de funct wood and
  • to remove the knots and interlaced branches.

Pruning is normally done 4 to 6 years interval depending upon the altitude of the garden, nature of the materials etc. the bushes marked for pruning should have adequate starch reserves in roots otherwise the sprouting following pruning should have adequate starch reserves in roots otherwise the sprouting following pruning will be less. This can be normally tested by the common Iodine test and if the starch reserve is less, bushes are allowed to rest for 2 to 3 months. The different types of pruning are as follows: -

Sr. N. Type of pruning Pruning height (cm) Season Remarks
1. Rejuvenation pruning 20 – China Jat,
30 – Assam Jat
April - May Done is old bushes affected with cankar and wood rot to invigorate the new healthy branches. Not done regularly.
2. Hard pruning 30 – 45 Apr. – May First formative pruning done to a young tea.
3. Medium pruning 45 – 60 Aug. – Sept. Normal pruning whereever frames are healthy.
4. Light pruning 60 – 65 Aug. – Sept. Normal pruning whereever frames are healthy.
5. Skiffing 65 Aug. – Sept. Mainly to postpone pruning and to encourage better frame development.

Immediately after the rejuvenation or hard pruning, the cut ends are smeared with a paste made of copper oxychloride and linseed oil (1:1). The prunings, consisting of only small twings and leaves are buried in trenches of 30cm width and 45cm depth taken across the slope in alternate rows. The pruned bushes are given washing with 10% lime solution using No. IV nozzle of power sprayers in order to kill the epiphytic growth of moss and lichen so as to induce early and even bud break. Lime washing also minimises sunscorch to the bush frame.

The buds from the pruned shoots grow in a steady succession without any cessation of growth. These are known as a periodic shoots or primary shoots. These primary shoots should be induced to produce flush shoots, otherwise known as periodic shoots by regular tipping operation. Tipping is the removal of terminal portion of the shoot and it varies with jats and pruning height as given below. Tipping height refers to the number of leaves that must be left above the pruned cut while tipping in material refers to that portion of the terminal shoot, which must be tipped off.

Pruning height (cm) Tipping height (cm) Tipping in material
China Hybrid Assam/
Assam Hybrid
China Hybrid Assam/
Assam Hybrid
China Hybrid Assam/ Assam Hybrid
35-45 35-55 5 4 3 leaves and a bud 4 leaves and a bud
45-55 55-60 4 3 4 leaves and a bud 4 leaves and a bud
55-75 60-75 2 2 4 leaves and a bud 4 leaves and bud
- > 75 - 1 - 4 leaves and a bud

Manures and fertilisers

Tea responds to manuring and it has been estimated that to produce 100kg of made tea, tea plant utilises on an average 10.2, 3.2 and 5.4kg of Nitrogen, Phosphorus and Potash per ha. Manuring in tea starts from nursery stage itself. Once they strike roots (after 4 months) 30g of soluble mixtures (Ammonium phosphate (20:20) 35 parts, potassium sulphate and Magnesium sulphate each 15 parts and zinc sulphate and Magnesium sulphate each 15 parts and zinc sulphate – 3 parts) is dissolved in 10 litres of water and is applied with rosecan for about 900 plants. This must be repeated at 15 days intervals.

Nitrogen: The recommendation for mature tea is based mostly on soil organic matter status and anticipated yield. For a field with medium organic matter status the following rates of application is suggested for every 100kg of made tea anticipated:

Yield level (kg/ha) Rate of Nitrogen (for 100 kg. of made tea) No. of split applications
<3000 10 kg 4
3000 8 kg 5
3000 and above 9 kg 6

Twenty per cent of the total nitrogen is given in the form of Ammonium sulphate during March/April. Urea is recommended in May/June and receding monsoon months avoiding very wet and very dry periods and it will come to 65% of total nitrogen. Fifteen percent of the total nitrogen is applied in the form of Calcium Ammonium Nitrate during pre-winter (November-December).

Potassium: Nitrogen and potassium are always applied together. NK ratio of 1:1 is used for plucking fields while for a pruned field 2:3 NK ratio is recommended. For rejuvenation pruned field 1:2 NK ratio is suggested. The enhanced rates of potassium application in the pruned year is to encourage formation of healthy farmers. Muriate of potash is the sources of potassium used in tea fields. The NK fertilizers are applied by broadcast for mature tea and is broadcast and dibbled in along the drip circle for young tea. The interval between two successive applications should be atleast 3-4 weeks.

Phosphorus: Phosphorus is applied once in alternate years @ 90kg P2O5/ha for fields yielding less than 3000kg/ha for fields yielding between 3000 and 4500kg/ha, 60 to 80kg P2O5/ha is suggested every year. The soils being acidic, rock phosphate could be advantageously used. The fertilizer should be placed at 15-22cm depth.

Micronutrients: Among the micronutrients, zinc deficiency is often manifested in young shoots characterised by reduced leaf size, rosetting, chlorosis and formation of more banji shoots. Application of zinc sulphate @ 6 to 8kg/ha for high yielding fields every year is the general recommendation. The above quantity can be given in 4 to 5 split applications during has been found beneficial to combine other micronutirents viz., Manganese sulphate @ 15.5g/10 litres and boric acid @ 5.5g/10 litres of spray volume along with zinc sulphate spray.

Liming: In the hill soils, due to the leaching of bases by rain and also due to the incessant application of acid forming fertilizers, the soil pH is often reduced which affects the physical and chemical properties of soil. Therefore, periodical application of lime is essential properties of soil. Therefore, periodical application of lime is essential to amend the soil and maintain optimum pH. Agricultural lime (Calcium carbonate) and dolomitic lime (Calcium Magnesium carbonate) are generally recommended for tea soils. The rate of application is based on soil pH, rainfall, fertilizer usage and length of the pruning cycle. Roughly lime @ 1.5mt/ha for a pH between 4.5 to 4.9, 3.0mt/ha for a pH between 4.0 to 4.4 and 4.0mt/ha for a pH of less than 4.0 is suggested.
The lime is applied by evenly broadcasting prior to pruning once in a pruning cycle. First manuring following liming can be had after 6 weeks and a minimum of 15cm rainfall should have been received during this period.

Harvesting or Plucking

Plucking consists of harvesting 2 to 3 leaves and a bud. It is the most labour intensive operation in a tea industry and also decides the yield and quality of made tea. Normally, a pluckable shoot takes 60 to 90 days for harvesting since its sprouting from the axillary buds. When the shoot is plucked upto mother leaf, it is known as light plucking and if it is plucked below mother leaf, it is called hard plucking. The plucking interval and plucking standard in relation to cropping is given below:

Cropping pattern Months Plucking interval
High cropping or Rush cropping (60% of total crop) April – June and October – December 7 – 10 days
Low cropping or lean cropping (40% of total crop) July – September and
January – March
12 –15 days
It is essential to add one tier of active maintenance foliage to the bush every year. This is done by mother leaf plucking during January to March. During the rest of the period level plucking can be carried out.

Consequent to plucking, bush height increases every year in the order of 10cm over tipping height in the first year, 7.5cm, 7.5cm, 5cm and 5cm over the previous year height in the second, third, fourth and fifth year respectively.

Yield

Yield of made tea per hectare depends upon many factors such as elevation, clonal or seedling jats, management practices, severity of pruning, processing techniques etc., Generally, in tea industry, a field which yields upto 2000kg of made tea/ha is considered as low yielding and 2000 to 3000kg as medium yielding and anything above 3000kg as high yielding fields.

Manufacturing of Tea

Basically, there are two types of processing viz.,

  1. Orthodox method in which the rolling operation is done in a series of rollers. The rollers have rotary tables with battens, jacket for loading the leaf and a pressure cup,
  2. CTC method (cutting, tearing and curling) which has a CTC machine, consisting of series of a pair of rollers mounted in such a way they rotate in opposite directions and the clearance between them is so adjusted to crush and tear the leaves.

Irrespective of the method, manufacturing of tea involves the following steps:

Withering: The objective of withering is to reduce the moisture content of leaves by spreading them in troughs which receive artificial air from fan fitted on one end. At the end of withering, the leaves attain a flaccid condition for which it may take 12 to 18 hours depending upon the weather condition.

Rolling: This operation is carried on by a series of machines or in a single roller, during which the cells in the leaves are broken to liberate the sap containing the polyphenol oxidase, an enzyme, which in the presence of oxygen, oxidises the polyphenols to produce theaflavins and thearubigens. These are responsible for colouring of the tea and is a 30-40 minutes. Afterwards, the fine sifted rolled ones are sent for fermentation while the coarse ones are again sent for rolling.

Fermentation: Rolled tea materials are either spread in concrete floors or kept in aluminum trays. In the presence of high humidity and proper step decides the quality i.e. strength, colour and briskness of tea. Fermentation requires 1 hour or 2 hours depending upon the environmental conditions.

Drying: This step aims at stopping the fermentation process and slowly removing the moisture content without a burnt smell but preserving the inherent quality. This is achieved by passing the fermented tea in thin layers through conveyors into a drier in which the inlet temperature is maintained around 250 – 2800F and outlet temperature is a round 150-2000F. Proper drying takes 30-40 minutes.

Grading: Before grading, the dried tea is removed of the stalky fibres, which affect the quality, by passing through fibre separate machines. The bulk tea is passed through different sized meshes which aid in separation into different grades.

Orthodox grades Mesh size CTC Grades Mesh size
Pekoe >8 mesh sieve Flowery Pekoe (FP) >8 mesh
Tippy golden Orange pekoe (TGOP) 8-12 Pekoe 8-10
Broken orange pekoe (BOP) 12-16 BOP 10-12
BOP – Fannings 16-18 Pekoe Fannings 12-16
BOP –dust 18-24 BOP – fannings 16-20
Dust – I 25-30 Pekoe dust (PD) 20-30
Dust – II Below 30 Red Dust (RD) 30-40
    Super Reddust (SRD) 40-50
    Finel dust (PD) 50-60
    Superfine dust (SD) Below 60

Plant Protection

Many pests and diseases are known to infect tea bushes and cause economic losses. The important pests and diseases, their typical symptoms and control measures are

Pests
Sr. No Pest Symptoms Control measures
1. Tea mosquitoes
(Helopeltis antonii)
Small adult bugs and hairy orange nymphs suck the sap from fresh leaves and tender shoots; leaves curl up, dry and die; active from January to September. Collect and destroy bugs during the initial stages; spray 0.1% Malathion or 0.05% Lindane
2. Shot-hole borer (Xyleborus fornicatus) Grubs make a typical short-hole on the branches and inside gallaries. A serious problem in low and mid elevation areas Badly affected branches are pruned off. Heptachlor 20 EC is sprayed @ 8.5 l in 675 lit. of water/ha on the pruned frames and prunings
3. Red spider mite (Oligonychus coffeae) Infests upper surface of mature leaves Tetradifon (8 EC) 1 to 1.25lit/ha.
4. Scarlet mite (Brevipalpus californicus) Discolouration of leaves often leads to defoliation  
5. Purple mite
(Calacarus carnatus)
Leaves exhibit smoky grey colour
6. Pink mite
(Acaphylla theae)
Young leaves turn pale and get twisted. Dicofol or Ethion @ 1lit. /ha.
7. Yellow mite (Polyphagota rosnemus latus) Infest pluckable shoot, leaves become rough, brittle and corky in under surface.
8. Thrips
(Scirtothrips bispinosus)
Leaf surface becomes uneven, curly and metty, exhibiting parallel lines of feeding marks on either side of the midrib Phosalone or endosulfon 1lit/ha.
9. Nematodes (Meloidogyne javanica,
M. incognita)
Occur in tea nursery, infested roots develop galls. Pre heat treatment of soil media upto 60-800C and application of carbofuran 3G @ 80g/m3 of medium.
Diseases
Sr. No Disease Symptoms Control measures
1. Blister blight (Exobasidium vexans) Infects tender leaves and stem and develops translucent spot. Cloudy and wet weather favour infection. Copper oxychloride 350g in 67lit of water with power sprayer for pruned field at 3-4 days interval. In the plucking Oxychloride + 210g Nickel chloride in 45lit of water/ha at 7 days interval.
2. Black root diseases (Rosellinia arcuata) Infested roots show black mycelium on the roots, white star shaped mycelium between bark and wood and Black lead shot like perithecia seen on collar region. The soil may be drenched with Dithane M-45 @ 30g/10 litres.
3. Red root disease
(Poria hypolateritia)
Infected roots exhibit blood red mycelium on washing. It spreads fast but slowly kills.
  1. Take trenches of 1.2m deep and 45 cm width sorrounding the infected bushes and uproot and burn the bushes in situ.

  2. Rehabilitate soil with gautemala grass.

  3. Soil fumigation with methyl bromide carbon-di-sulphide
4. Brown root disease (Fomes noxius) Infected root wood turns soft and spongy, it spreads slowly but kills quickly.