Tea Handout 2024 PDF

1 Chap II : TEA 2.1 INTRODUCTION Tea Camellia sinensis belongs to the family of Theaceae which has about 20 genera and 200 species. The only important economic species being Camellia sinensis. Camellia sinensis is a dwarf slow growing tree with small erect a...

1 Chap II : TEA 2.1 INTRODUCTION Tea Camellia sinensis belongs to the family of Theaceae which has about 20 genera and 200 species. The only important economic species being Camellia sinensis. Camellia sinensis is a dwarf slow growing tree with small erect and comparatively narrow dark green leaves. The probable origin of Tea is said to be near the source of Irrawaddy river and from there it spread to South eastern China, Indo-China and Assam. In these areas tea is found growing in the wild. Tea has spread into tropical and subtropical countries and during the 19th century it developed into an important plantation crop. Its spread was championed by the British Empire; first in the Indian subcontinent then in East Africa where it reached later in the 20th century. Tea has grown in China from very long times and it was probably used for medicinal purposes but leaves have been used as beverages for the last 2000 to 3000 years. Green tea is made from leaves, which are streamed and dried without wilting or fermenting. On the other hand the main form of tea is the black tea leaves which have been wilted, rolled, fermented and then dried. Although tea was taken later than coffee (16th century) to Europe, it gradually replaced the latter in UK and consequently in the British Empire. In the world trade, tea comes second after coffee in beverage. By far the largest consumer of tea is UK, which takes the half of World’s import and where the per capita consumption is nearly 4.5 kg per year, the second largest importer is the USA but their per capita consumption is only 0.35 kg per year. In Rwanda, Tea crop was introduced in 1960’s as cash crop for export purpose. Black tea manufacturing followed in 1965 at Mulindi tea factory in the Northern Province. Since mid 1970 tea sector has become significant and is now the most important source of export earnings after the coffee market plunged in recent years. Tea contributes up to 34% to national exports. Tea has a high potential in Rwanda’s agriculture for the following reasons: - 1/3 of the Rwanda’s arable land is acid and tea has been found to grow successfully on such lands, - Tea crop provides an essential soil cover, on steep hill, prone to soil erosion where it is currently growing, - Rwanda tea is among the best quality tea in the world, - Rwanda needs to diversify its export crops (especially Rwanda being a small producer can never influence the world market). - Tea provides employment and cash in the rural area where both are very much needed. 2.2 TAXONOMY AND VARIETAL DIVERSITY Various botanical varieties have been selected from time to time. The term jat is used to indicate seed derived from different districts or plantations or to separate types on the basis of  2 foliar characteristics. The correct botanical name of cultivated tea is Camellia sinensis (L.) O. Kuntze, regardless of varietal differences, and it consists of three distinct three main groups:  China teas, Camelia sinensis var. sinensis These are slow-growing dwarf trees, with small erect comparatively narrow markedly serrate, dark green leaves; flowers borne singly; low jats, resistant to cold and adverse conditions but rather low yielding and originated from China.  Asian teas, C. sinensis var. assamica They are quick-growing taller trees with large, drooping leaves; flowers in clusters of 2 - 4; high jats; well adapted to tropical conditions. These are sometimes divided into: i) Assam types proper: these have light green leaves giving larger yields of better quality tea, less hardy and were restricted to the Brahmaputra valley where climatic conditions are not so severe. ii) Manipuritea types: these have dark green leaves and are drought resistant but with poor yield and quality. The important variety mentioned is macrophylla Makino; it is a large-leaved triploid from Japan, which gives a bitter decotion.  Cambod – C. sinensis var. assamica ssp lasiocalyx (Planchon ex Watt). It is a hybrid between China and Assam varieties, with semi-erect leaves. It is found in Indonesia but it is not common in Africa Numerous hybrids between China and Assam types are known and are grown around Darjeeling in India. As tea is largely cross pollinated and most commercial tea is raised from seeds, the crop is very heterogeneous. Using chosen vegetative characters commercial tea types from a clone (mixture) extending from plants of Chinese origin to those of undoubted Assam origin. 2.2.1 CLARIFICATION OF NOMENCLATURE Originally, Linnaeus classified tea as Thea sinensis (1752). Later, two varieties were identified and classified by Masters (1844) as Thea sinensis (China type) and Thea assamica (Assam type). Thea and Camellia were thought to be separate genera. However, Thea is actually classified as a section within the genus Camellia, and C. sinensis is classified under this section. The genus resembles and interbreeds freely with tea. However, hybrids with tea do not produce suitable tea beverages. C.sasanqua Thumb is a wild non-tea species found in Japan. Some of the wild species are resistant to environmental stress (e.g. drought, cold temperatures, pests and diseases) and, therefore, can be used as a source of resistance genes in tea breeding. 2.3.ORIGIN, EVOLUTION AND DISPERSAL The probable origin of Tea is near the source of Irrawaddy River and from there it spread to south-eastern China, Indochina and Assam (India). It is variously stated that tea is found wild in  3 Assam and Upper Burma and in South Yunnan and upper Indo-china, but the possibility of these plants being escapes from cultivation must not be overlooked. From the main centers in south eastern Asia, with traditional peasant cultivation, tea has spread into tropical and sub-tropical countries and during the 19th century it developed into an important plantation crop. It was introduced into Japan at an early date. Experimental plantings were first made in India between 1818-1834 from seeds originating in China. With the discovery of wild tea in Assam and Manupur, commercial plantings were made with these local types from 1836 onwards. The main areas of cultivation are hilly districts of north eastern and southern India. Tea was unremunerative until Assam types were introduced in 1878. Extensive tea plantations began in Ceylon (now Sri-Lanka) in 1870 replacing coffee, which had been devastated by Coffee leaf rust. Tea was first planted in Russia in 1846, but the first successful plantations in Georgia were begun in 1895. Tea has been tried in most tropical and subtropical countries including the New World and there are small plantations in Argentina, Brazil, Chile and Peru in the Andean regions. Tea was first successfully introduced into Nyasaland (now Malawi) in 1886 and the first estate was planted in 1891. Introduction into East Africa at the beginning of 20th century led to commercial production in the 1920s – 1960s in Kenya, Tanzania and Uganda. In Rwanda, Tea crop was introduced in 1960’s as cash crop for export purpose. Black tea manufacturing followed in 1965 at Mulindi tea factory in the Northern Province. 2.4 CHEMICAL COMPOSITION I. The most important constituents which give tea its distinctive character as a beverage are polyphenols, caffeine and essential oils. II. Fresh plucked tea contains 75 - 80% water, the soluble and insoluble constituents on an approximate dry weight % include: polyphenols 25; caffeine 2.5 – 4.5; crude fibre 27; carbohydrates 4; pectin 6. III. The polyphenols derivatives of gallic acid and catechin, but not tannins in the normal sense, are oxidized by enzyme action during maceration and fermentation to produce O- quinones, which polymerise to produce coloured astringent condensation products and these are partially extracted in brewing tea (they are little changed in green tea where no fermentation is done). IV. The polyphenol and caffeine contents are highest in the bud and top leaf of a flush and diminish in successive leaves and stalk. V. Good quality tea is a product of good leaf with high polyphenol content and high enzyme activity; it also shows a correlation with the hairiness of a flush:  Coarse plucking in which more than the bud and 2-3 leaves are taken reduces quality;  4  Slow growth at high altitudes in the tropics (perhaps because it increases the concentration of polyphenols) increases quality. VI. The aroma and flavor are also affected by various substances including essential oils. VII. Fresh manufactured tea should have moisture content of about 3%. VIII. The professional tea tester infuses tea for 5 minutes and the extract contains about ½ the polyphenol products, ¾ of the caffeine and about ½ the total extractable solids. IX. Seeds contain 20% of non-drying oil, but it is not extracted commercially. 2.5 ECOLOGICAL REQUIREMENTS I. Tea cultivation is confined mainly to the subtropics and mountainous regions of the tropics, near the Equator between 1200 – 1900 m. II. Tea requires equable (moderate) temperature and moderate to high rainfall and high humidity throughout the greater part of the year, it will not tolerate frost and China teas are more tolerant to colder conditions. III. Best quality tea is produced in a cool climate e.g Himalayan foothills of north eastern India. IV. Regardless of whether or not other climatic factors are favourable, tea, like other plants, does not grow when temperatures are either too low or too high. Mean minimum temperature should not fall below 12.8oC and the mean maximum temperature should not go above 23.9oC. V. The minimum annual rainfall considered adequate for the successful cultivation of tea is about 1200 mm without irrigation. Water is removed from the soil by tea roots and lost from the leaves by evapo-transpiration at a rate which varies from 120 mm to 180 mm per month depending on the prevailing weather conditions. Ideally therefore water should be available to the roots in amounts which are of this order each month. Where there are prolonged periods when rainfall is less than the water lost by evapotranspiration, the plants must rely on stored ground water. If irrigation is intended to be used or is found desirable on consideration of the climate, the availability of water must be investigated. VI. Hail can cause much damage. VII. Tea is known to demand, perhaps more precisely than any other crop, soils with special characters if economic yield is to be obtained. The best soils for growing tea are deep, permeable, well-drained and are often tropical red earths, the pH should be between 4.5 and 6.0. VIII. Tea is calcifuges (not liking free CaCO3) and is an aluminium accumulator and this element should be available in these soils. IX. The vegetation on the area is a very useful guide. If the area is already cultivated the condition of the crops can give some indication of the fertility status of the soil. Analysis of natural vegetation where this is largely of one species can sometimes give some guidance. One characteristic property of the tea plant, its ability to accumulate aluminium, gives rise to a very convenient method of recognising a potential tea area. Albizia spp., Dissotis spp. and brachen (igishiha) are sometimes used as indicator plants in selecting sites for tea.  5 2.6 PHYSIOLOGICAL DESCRIPTIONS The commercial cultivated variety of Tea is a population of heterogeneous hybrids between varieties assamica and sinensis with introgression with other species of Camelia. That material is well adapted to high altitude conditions. Tea is diploid and has 30 chromosomes. There are considerations with several physiological implications concerning pruning; height; importance of photosynthesizing leaves; manner of plucking and types of clones used: - Tea must be pruned as low as possible to limit the excesses of the frame. - The photosynthesizing foliage must be large enough to provide for the regrowth of young leaves and roots. - The removal of the ageing photosynthesizing foliage is necessary for more efficient photosynthesis. - The clones used must be the most performing types in terms of density, weight and quick growth of young leaves and high quality tea. 2.7 TEA RESPONSE TO WATER STRESS In Rwanda the dry season experienced from June to September results in the decline of production. Different responses to droughts are manifested by different tea clones. The clones most tolerant to water stresses are those which can maintain a high gas exchange during day time and those, which can retain their cellular turgidity. These two conditions are necessary to keep photosynthesis going on. The maintenance of cellular turgidity is related to the great efficiency of the rooting system capable of extracting enough water from soil or to the possibility of adjusting osmotic pressure at stomata level. To maintain a reasonable production during the dry seasons demands that clones tolerant to water stress be used. 2.8 BASIS OF VARIETAL IMPROVEMENT Most tea has been planted from seed and as the flowers are cross-pollinated tea is very heterogeneous. Much of the yield of an individual field is contributed by a relatively small number plants i.e in Ceylon, in an improved field, the number of pluckable shoots on 1,515 bushes, randomly selected, varied from 20 to 1000 and less than 5% of the bushes gave count above. There is a considerable variability on which to base selection including hybrids of China & Assam types: - It should be possible to combine: Aroma and hardness of China tea with the hardness, vigour, large leaves of Assam; - Then clones can be propagated vegetatively. The final aim is a high yield of tea of acceptable quality from clones, which may be successfully propagated vegetatively. Yielding capacity is based on the yield per unit area of bush surface, which is dependent upon the number of plucking points and the size of the shoots. The following characters are used in selections:  6 - Vigour, with a bush that comes into plucking quickly and gives continuously high yields; - Adaptability to local conditions including drought resistance for dry area and frost resistance where required; - Hairiness of terminal buds indicating high polyphenol content; - Bushes with spreading habit & tight plucking table with ample leaves below the plucking tables; - Few dormant and without tendency to flower; - Evenness of flush: even first growing of leaves; - Large, heavy shoots with long internodes without markedly erect leaves (as they are more difficult to pluck). - Flexible leaves which are easier to roll during processing; - Leaves fermenting easily, of good colour (in the finished product) aroma and astringency; - Clones that root easily from cuttings; Selection will involve visual selection in the field, in which pickers with an intimate knowledge of the bushes may use:  Testing in the nursery for rooting ability of the cuttings,  Testing in field trials for growth habits,  Testing quality of final tea. 2.9 CULTURAL PRACTICES Tea plants can be raised from seed, cuttings and tissue culture (micropropagation). Propagation from seed is less common nowadays following the development of operationally easy, rapid and cheap techniques of vegetative propagation (VP), which facilitate easy production of clones. However, if required, open pollinated seed can be supplied from tea breeding seed baries (gardens). Tissue culture is rapid and economical on space. However, it is costly for use in micropropagation and is appropriate mainly for breeding purposes. 2.9.1 Seed propagation (i) Selection and treatment of seeds: - Bushes of high quality and yield are selected as seed bearers. They will have been planted in well fertilized and looked after gardens. - There are normally plants from selected clones propagated vegetatively. The trees are shaped to low branching. - Ideally, the seeds should be collected from the ground daily, and should not be left longer than two days. To facilitate collection, ensure that the ground is smooth and free of weeds. Start the season by sweeping away all the old seeds. - Selected seeds are then graded by passing through mesh and rejecting those going through the 12.7 mm mesh. They are then immersed in water for 24 hours and rejecting those which float. The large seeds should then be picked up by hand and all bad seeds discarded, e.g.  7 the black, very pale, rotten or empty seeds. Cracked seeds should be planted immediately. Small seeds are likely to be genetically inferior and should be discarded. The selected seeds (of good quality) can be treated using methyl bromide, in which case they are planted immediately or they could be treated by immersing them in hot water (52oC) for 30 minutes (this treatment kills insects and speeds up germination). (ii) Germinating the seeds: - Tea seeds loose viability quickly; they should be germinated as soon as they are picked. - Cracking the seed coat will speed germination. They are germinated on sand covered with a wet heasin. (iii) Site of nursery and land preparation: The site should be protected against wind, cold and be near water source. The soils should be deep (2 m), free draining and friable, marsh lands and alluvial soils should be avoided. Both the top soil and sub-soil should be tested for pH, which should be between 5.0 and 5.8 with 5.6 being optimum. If the soil pH is higher than 5.8, acidify the soil with sulphur at the time of digging the nursery beds. Areas liable to damage by hail should be avoided, or protective measures using high polythene nets with appropriate mesh are used for important breeding stocks during periods when hail may be prevalent. The Assam (Camellia sinensis var. assamica) type of tea takes 4-5 years to flower at high altitudes and about three years at low altitudes, but as a long term investment, the differences on the initial time to flowering should not be regarded as a major constraint. For seedling stumps, the nursery site should be dug over to a depth of not less than 75cm. The soil should then be roughly levelled and beds marked out; the beds should be no wider than 1½ m, and between adjacent beds there should be a path about 45cm wide. The beds should be aligned so that these paths can act as drains. Soil should be removed from the paths and placed on the beds until the beds become raised 15cm above the paths. The beds should then be raked to provide a soil of fine tilth. For sleeved plants forking to a depth of about 30 cm should loosen the soil below sleeves. The sleeves must be supported by light walls or wire round each bed; walls are preferable as they will later shade the sleeves on the edges of the beds and prevent the roots in these sleeves from being sun-scorched. The nursery should be provided with light dappled shade which in a high shade nursery, should be raised at least 2 metres above the beds so that it is easy to walk in the nursery. Some areas need no shade, but if there is any doubt it is safer to have the shade. The shade should be thinned out gradually so that it is completely removed three to six months before transplanting stumps. Sleeved plants can be transplanted as soon as the shade has been completely removed. (iv) Transplanting the germinated seeds: Germinated seeds are transplanted in beds at a spacing of 12.5 cm x 12.5 cm. It is better to have seeds of same germinating stage to have homogeneous seedlings.  8 (v) Maintenance, fertilizer and irrigation of the nursery: The material from shade is removed gradually and weeding is done regularly. Fertlizer to produce strong stump with NPK 1:2:2 or 1:2:3 at rate of 150 g/m2 with many applications in 2 years. Fertilizing starts when plants have 6 to 8 leaves; the first applications are done in solution every 15 days applying 50 g in 10l of water for 25 m2 applied between rows. Application can also be done foliarly, but then rinsing with water to avoid plant burning. Irrigation is done quite regularly. 2.9.2 Vegetative propagation 1. Necessary conditions and selection of cuttings: Successful vegetative propagation is possible under the following conditions: (1) using rootable clones, (2) using substrata of poor organic matter, (3) maintenance of high relative humidity and providing beds with good draining system. Cuttings are selected from high performing clones. 2. Choice of nursery sites: The site should be near a water source because of irrigation needs. The site should be protected from wind, sun and cold (avoids valleys in the high altitude where temperatures can be very low). The site should be near source of sub-soil. For large nurseries the site should be accessible (good roads) to facilitate transportation. 2.9.3 Land preparation In a new area, which has been under forest, it is necessary to clear the forest thoroughly in order to avoid disease transmission to tea. Trees are destroyed by ringing them or using herbicide (245 - T) before uprooting. Old stumps must also be removed if they show any symptoms of the diseases (Armillaria mellea). Land shall be leveled after wood is cut; it is then thoroughly ploughed removing all woody trash. In case of grassland, grass shall be cut and removed before ploughing. After ploughing, the land shall be leveled, and the roads and paths put in place where appropriate. Then there will be a picketing to determine the contours for soil erosion measures. The basic lines are put in first and the lines for tea later (placed in between lines depending on spacing). 2.9.4 Field planting Plants raised from seeds are ready for planting when the collar size is 15 mm in diameter. It is approximately after 24 – 30 months of nursery at an altitude of more than 2000 m. The place is subjected to decapitation at 10 cm from the collar and to the treaming of the root cuttings, thus leaving a stump 55 cm long. Seed bed which had been ploughed thoroughly and thus with soft soils the plant can be pulled out, always with care to avoid damaging the root. The hard seed bed, the plant can be pulled out after making a hole in front of the plant and with the use of a spade the plant can be uprooted in both methods. The soils removed by making the  9 holes is mixed with 30 kg of N, P, K and put back to fill the hole after planting, to avoid depletion around the tree, the soil level shall be raised around the plant making a small mound. Immediately after planting the plant is shaded using a few ferns. The rooted cutting is ready for transplanting when its roots reach the bottom of the bag; the plant shall be about 20 cm tall and have 10 to 12 months after planting. For transplanting, always choose the most vigorous rooted cutting. It must have been acclimatized for 3 – 6 months before transplanting. Transportation must be carefully done to avoid disturbing cuttings in transit (keep the lump of soil around roots intact and humid), irrigate plants before transport and in transit, pack the plants closely and in a vertical position. The hole is 40 cm deep, (15 cm longer than the bag). After making the hole, the soil is mixed with fertilizer 30 g of (TSP, DAP & K2SO4) each plus 2000 g of compost. The bag is moved and the rooted cutting is placed in the middle of the hole still with a lamb of soil which should be 2.5 cm above the hole. 2.9.5 Planting time Planting should be avoided in excessively wet weather to prevent soil from puddling around new plants. The ideal planting time is when the soil is damp, rather than wet, and the weather is cloudy. Once the rains have started, planting should normally commence as soon as the soil is found to be damp to a depth of at least one metre. Therefore November and December period is the most favorable, soil is sufficiently moist from September/October rains. Planting in January is also favorable as plants should have a long period (5 months) of rain before being exposed to dry season. It is also possible to plant just after the small dry season of February but not later than March (Because dry season would be soon approaching). 2.9.6 Fertilizer application Fertilizer for young tea: Young tea plants require much fertilizers,for their size as when in full cropping. Fertilizers should be a compound or mixture providing N,P,K and S in the proportion of 5:1:1:1 or or more concentrated in P and K, as for mature tea. Fertilizers for mature tea: In mature tea plantation fertilizers are applied at a rate of NPK 25:5:5 refering to the percentage of N, P2O5, K2O and S respectively. Tea under severe nutritional stress should receive a curative fertilizer application as soon as practicable. It is assumed that all prunings will be left in the field and decomposing pruning leaves and soft twig will return nutrients to the soil. Splitting the annual fertilizer program may be adopted in order to lessen the risk of increasing already excessive crop in certain seasons. If this is done, the overall efficiency of the fertilizers may be reduced, in terms of quality of crop produced (TBK, 2002). 2.9.7 Wind break Tea is sensitive to wind; because wind reduces humidity around the canopy, this tends to increase transpiration of tea and thus producing a negative effect on the performance of tea. Consequently tea has been reported to benefit from wind breaks. In Tanzania where Hakea  10 saligna was used as a wind break it increased tea yield especially in the dry and cold season. Tea itself may also serve as a wind break. This is easily achieved by allowing one row of tea to grow freely then prune it to produce a continuous belt which is perpendicular to the wind direction. Pruning of lateral branches is done with care to avoid making openings for the wind. Tea as a windbreak is well adapted to plantation in blocks. 2.9.8 Weed control Weeds compete with tea for water and nutrients. Early weed control can ensure early development allowing early and effective pruning thus maximizing yields. Clean weeding on slopes should be avoided to stop erosion. There is also need to devise weeding which does not harm superficial roots of tea. Dicotyledon weeds are removed early before they set seed, it is done by scrapping in order to avoid cutting the feeder roots of tea; monocotyledons especially the cutch grass is removed by the use of hoe or trident. Hand weeding using hoes does not remove all the cutch grass and in addition it harms superficial roots of tea. 2.9.9 Bringing tea into bearing Any operation designed to form a permanent branch system, from the time the plants are in the nursery to the time they are tipped-in to form a plucking table in the field, is defined as ‘’ bringing tea into bearing’’. These are systems of bringing tea into bearing which were developed for the formation of good permanent frames, namely: pruning, pegging and tipping (TBK, 2002)  Pruning Whenever a shoot on a tea plant is removed, axillary buds are stimulated to develop for a distance of about 10 or 12 cm below the cut. This stimulus occurs if soft apical shoots are removed, as at tipping-in to form a table, during regular plucking, or if thick stems are cut, as during hard pruning and during preparation of stumps from the nursery. Tea is a permanent low and branchy frame capable of producing plucking table, which is easily acceptable. - First the shoot is decapitated at 15 cm from the ground when it is 30 cm high and has more than 3 leaves. - When it has less than 3 leaves, it is decapitated later when it reaches 20 – 25 cm. - Two prunings are done after decapitation, the first at 28 cm the second at 40 cm, most branches should be having more than 10 mm in diameter. Generally the first pruning is done 18 – 20 months after plantation and the second 12 to 15 months later.  11 - Tea is never harvested after the first and second prunings, in order to allow sufficient root development; enough reserves of carbohydrates into roots and this ensures greater performance at later stages. - After the second pruning for frame formation the plucking table is allowed to form at 60 cm from the ground. Pruning a seedling stump at 20 cm Pruning a seedling stump at 40 cm Diagrams of bushes immediately after pruning at 20 cm and 40 cm and after tipping at 60 cm.  12  Pegging The shoot which develop from a stump or after the first light prune of a sleeve plant are bent downwards and pegged so that they radiate outwards and upwards from the main stems. These pegged branches form the basis of the permanent frame which is added to the vertical shoots that develop from axillary buds along the branches. The development of these axillary buds is encouraged by pegging the branches so that they slope uniformly and slightly upwards; it is retarded or even prevented if the branches are pegged so as to be horizontal or to slope downwards. If the branches are pegged so that they curve upwards at first and then downwards towards their tips, the axillary buds will generally develop only along the upward-sloping portion near the main stem. Further encouragement to development of the axillary buds is given if two terminal leaves and a bud are removed from the pegged branches at the time of pegging. The pegging system of bringing stump-plants into bearing into bearing (A) Newly pegged bush (B) The same bush after tipping (C) Two types of pegs.  13  Decentring: This system entails tipping shoots (three leaves and a bud) of a tea plants at gradually increased heights. Establishment of a plucking table - The plucking table aims at maintaining foliage (which is the site of photosynthesis) and a flat surface for harvesting high density young growths. It is an important execution which must be done with care to provide a plane which is parallel to the ground level of the whole field. How the plucking table is established? 1) It is established after pruning by tipping; 2) After subsequent production pruning, tipping is done at 15 or 10 cm above the plane of pruning depending on the height of pruning; 3) 3 to 4 tippings are necessary to establish correctly the plucking table; 4) Tipping begins with growth reaching the fixed height (60 cm) a. Tipping of top shoots induces axillary buds to grow b. Continuous tipping will result in a dense growth towards the wanted level 5) Interval of tipping depends on the rate of growth of the buds which in terms depends on climatic and nutritional factors. 6) Tipping is done by hand and the use of the frame can assist in indicating the fixed level of the table whose plane must always be parallel to the ground level. Harvesting or plucking - Harvesting involves periodical removal of new growth of the plucking table. - The plucking table is the level at which the regrowth is plucked, one cannot pick below. - The establishment and maintenance of this table is important:  It allows and facilitates to see what to pick;  It permits the supervisor to control the harvesting. - It is difficult to pick on very high or very low levels. - Plucking table is easily formed after pruning and is maintained by correct plucking when it becomes irregular it should be relevelled by appropriate plucking.  14 - It is important to pluck regrowth when it is large enough to ensure sufficient yields, but also not to pick too old leaves, as they will lower the quality. Two groups of terms are used in describing plucking standards. The first pair of terms relates to the type of shoot that is sent to the factory: -  'Fine' plucking is the removal of one or two leaves and the bud.  'Coarse' plucking is the removal of three or more leaves and the bud. The second pair of terms relates to the amount of new foliage left on the plucked shoot above the plucking table: - 'Light' plucking leaves some new foliage above the previous plucking level. 'Hard' plucking means that the shoots are plucked right down to the previous plucking level so that new maintenance foliage can hardly develop. It is possible to combine the pairs of terms to obtain four basic types of plucking: Fine and light, fine and hard, coarse and light, coarse and hard. In general the finer the plucking the better the overall quality of the made tea Light plucking ensures that the adequate depth of maintenance foliage is present on the bush, but if the plucking is too light then the plucking table rises rapidly and the potential crop is thus wasted by leaving pluckable leaf on the bush. On the other hand, hard plucking cannot be continued indefinitely as at some stage new maintenance foliage must be permitted to develop on the surface of the bushes. The leaf standard set by the factory must not be too rigid, but should indicate the maximum permissible proportion of over-standard and damaged shoots that can be accepted. No plucking can be entirely "two leaves and a bud". There will be always be a number of 3+ bud shoots, banjhi shoots, broken shoots and detached leaves. During plucking, soft banjhi shoots must be plucked as soon as they rise above the plucking table; if left they might become too hard at the next plucking round. Thus hard banjhi shoots should not normally be found above the plucking table, but if they do occur they must be plucked and discarded (breaking-back) unless the banjhi state is caused by drought.  15 Banjhi shoots below the plucking table should not be plucked. They are part of maintenance foliage and are useful as their leaves are efficient at manufacturing the sugar, which is utilised by the rest of the bush. Pruning tea bushes in production - Pruning maintains plants in permanent vegetative phase. - Stimulates plants to produce new shoots capable of production in continuous manner new harvestable growth. - Maintain the bush at permanent height permitting easy harvesting. - Renew the branches of the frame. Pruning for production 1. Successive harvesting raises progressively the plucking table (10 cm) per year. This leads to the following situations: - Maintenance foliage gain non functional leaves. - At the end of 3 – 4 years the plucking table is 1.05 m height beyond which plucking becomes difficult to execute. - Productivity of the bushes also declines. 2. The plant wood has thus to be rejuvenated by pruning: - Force buds of the branches to form new branches. - Form new maintenance table. - Re-establish new accessible plucking table. 3. The execution of pruning for production is done as follows: - It is done 5 cm above the level of previous pruning. - A simple transversal cutting is affected without disturbing the centre. - After one production pruning, the plucking table is at 15 cm above the previous one. 4. Frequency of pruning for production - Length of cycle depends on ecological factors (climate & soils); - In tropical Africa the cycle is fixed at 4 years;  16 - In industrial blocks they prune annually all hills making up of ¼ of the total area. 5. Period to prune for production - When carbohydrate reserves in roots is the highest (immediately after dry season). In October when most of carbohydrates shall have gone to roots because of reduced above ground growth. - Bushes showing no exhaustion from plucking can also be pruned in June (end of season). - It is also recommended that 60 g of NPK (30-10-10) per plant be applied after establishment. 2. 10 PROCESSING The process of tea manufacture, converting plucked green tea leaves into the final saleable consumable product, is a vital step in the production of black tea. Good manufacturing practice can produce the best tea from the available good leaf, and hence realise the best market price. It is important to note, however, that the quality of tea produced depends on the leaf that is plucked, the type of tea bush, how the leaf is handled, the time of the day or of the year from prune, the standard of plucking, fertiliser rates and types. The manufactured tea is composed of small particles which give it its special characteristics. Transformation mostly involves polyphenols and their derivatives namely: galatte epigallacatechin, galloacatechin, epigallocatechin, galatte epicatechin, epicatechin, gallocatechin and catechin. These compounds give tea its nature: vivacity, colour and force. The concentration of polyphenols is genetically determined and modified by the environment (i.e decreasing with aging and increasing with altitude).  Process of tea manufacturing Reception of leaves Leaves arriving at the factory are weighted first and then unloaded on a dry floor; they are put into canvas netted sacs. Samples are then taken to check the quality and composition. Sacs are hung to the monorail to be transported to the wilting room. Wilting The purpose of wilting the leaves is to give them flaccidity by evaporating some of their water, the operation is done in wilting troughs. The floor of the trough is perforated and permits a flow of air coming from a system of reversible vindications at one end and a radiator at the other, this permits the wilting of the leaves by passing this hot air at flow of 500 m2 per minute over the leaves. Leaves are wilted to 70% water content in a period of 12 - 18 hours.  17 Wilted leaves are reloaded into canvas sacs and conducted to the crush, tearing and curling (CTC) room. Before being put under CTC they are first sieved to remove foreign materials (soil, residues, dried leaves, metallic particles, etc). Crushing, tearing and Curling (CTC) The purpose of crushing, tearing and curling is to break cellular walls and expose polyphenols and enzymes to air. Wilted leaves are chopped first by a rotavane, they are then torn by another machine with 70 – 700 revolutions per minute. After crushing, tearing and curling, chopped/torn leaves are further reduced to finer particles by subjecting them to a Laurie tea processor (LTP). This machine has an added advantage of computerizes and easy maintenance and use. It also adds grade to the product. Fermentation Fermentation begins in the CTC, where crushed and torn leaves will have been exposed the polyphenols and enzymes to the air. It is completed in the fermentation tanks where temperature and humidity are controlled. A certain humidity is maintained to avoid drying. Fermentation must be done slowly to ensure the vivacity, brightness and flavour of tea. Duration of fermentation depends on ambient temperature and last usually 1.30 hours. Drying Drying is interdict to stop fermentation and chemical reaction while reducing the moisture content to 3%. The water of the dhool is reduced to a half by evaporation using a jet of hot air. The drying is gradual: the dhool first comes into contact with warm air of (50 -54)o C which is raised gradually to (90 -95)o C. A uniform drying is achieved in 20 minutes. Driers are made of moving perforated containers placed on stairs and accomplish 180 kg of dry tea per hour. Modern factories are equipped with driers which can dry 350 – 400 kg of tea per hour. Setting and grading tea After drying tea is cooled and graded into several classes called grades depending on the size of particles (the smaller the particle the higher the grade). At the beginning of grading, tea is divided into 2 categories called lines: the first and second lines, which shall be later grades separately. - The first line has the following grades: 1) PF1 (Pekoe Fannings one) 2) PF (Pekoe Fannings)  18 3) PD (Pekoe Dust) 4) BP1 (Broken Pekoe one) - The second line has the following grade: 1) BP (Broken Pekoe) 2) F (Fannings) 3) BMF (Broken Mixed Fanning) Packaging Because the same grades produced on different days are not always similar especially in color, they must be mixed before packaging to produce uniformity. Quality control and factory hygienic conditions Good manufacturing practice can produce the best tea from the available good leaf, and hence realise the best market price. It is important to note, however,that the quality of tea produced depends on the leaf that is plucked, the type of tea bush, how the leaf is handled, the time of the day or of the year from prune, the standard of plucking, fertiliser rates and types. Quality controls are done daily by tea makers who check and note the relative humidity, grades of tea and liquor or quality. Because tea is a food commodity it needs hygienic conditions during its preparations; to avoid its contamination the following measures are taken during tea manufacturing process: a) Leaves should never come into contact with soil. b) Machines should be cleaned of bacteria to avoid contamination. c) Dust should be eliminated in all places the tea passes. d) Corporal clear lines for workers (Washing, clear uniform is obligatory). 2.11 TEA PRODUCTION IN RWANDA In Rwanda, Tea crop was introduced in 1960’s as cash crop for export purpose. Black tea manufacturing followed in 1965 at Mulindi tea factory in the Northern Province. Since then tea sector has become the most important source of export earnings after the coffee market plunged in recent years. Tea contributes up to 34% to national exports (MINAGRI, 2008). 2.11.1 Tea plantation management systems in Rwanda The total planted area is 17,771 ha, and provides employment to 52,838 people (Ocir-the, 2010). There are three systems under which tea plantations are managed in the country:  19 a. Industrial blocks (Factory gardens): These are plantations which are established and managed by OCIR-THE or Private companies. They cover 6310 ha or 35.5% of the total tea production area. b. Coopthe (Cooperatives of tea growers): These plantations are owned by cooperatives of tea growers. They were established by the government with help of the European development fund. They cover 1176 ha or 9.9% of the total tea production area. c. The villageois (TV): These are smallholder plantations belonging to individuals, working in groups or alone. The plot for TV occupy between 0.2-0.5 ha. They depend on family labor and get a regular income throughout the year. TV cover 9685 ha or 54.6% of the total area. d. Recommended agricultural practices of tea in Rwanda 1. Type of soil: Tea is grown in well cold regions on deep and well fertilized soils. 2. Available varieties for dissemination: BWG/5, 31/11, BB/356/8, BB/10, 12/56/, BU/105, 12/19, 11/4 and others. 3. Land preparation: The main activities related to land preparation are: Putting in place erosion control systems, ploughing, digging holes. 4. Fertilization: Use 60gr of NPK 25:5:5 per plant and apply it when it has taken root. 5. Seedling planting: Plant 105 seedlings per are with 130 cm of spacing and 75 cm between holes. The total number of plants per ha is 10500. Tea planting takes place in Octobre- Decembre on hillsides and in February-March in well drained mashlands or valley fields. 6.Planting management: The following activities shall need farmers special attention: weeding and hoeing, drainage, mulching, planting trees to slow down the impact of the wind on the field, pruning, replacing missing seedlings and fighting against diseases and pests to tea plant. 7. Main tea diseases and pests a) Root rot disease: This disease is transmitted by a fungus called Armillaria mellea which attacks the roots of the plant and makes them rot. The symptoms of the disease: The growth of tea plant obviously slows down, its leaves become yellow and fade, and eventually the whole tea plant gets rotten and dry out. A deep crack appears at the base of the trunk and in the main roots. Inside, the crack and white patches develop under the bark. Control measures: Uproot and burn contaminated tea plants as soon as the first symptoms are identified. Note: Stumps of trees surrounding the fields or planted on the embarkment along erosion control ditches often transmit the disease to the plantation. This disease is frequent in wet soil.  20 b)Brown spots: The disease is transmitted by a fungus called staliopsis theae.It attacks leaves and makes brown-greyish round spots on leaves, the spots are whitish inside and grayish on the contour. Control measures:  Avoid anything that could hinder tea plant growth  Avoid fertilizers with high concentration of nitrogen  Early pruning and mulching  If the presence of the disease is confirmed in the nursery apply Mancozeb (Dithan M45) c) Red spider: This disease is transmitted by a spider called Oligonichus coffea.  It is a small insect(0.5mm);with red coulor when it is adult. The young and adult insect live on tea plants and feed themselves on lower faces of the leaves, suck water from them. Attacked leaves become redish.  Progressively, the leaves dry out and eventually fall. Attacks by these insects are particularly frequent during dry season Means of fighting against the diseases: Use Dimethoate In case of dimethoate is used to fight against the red spider leaf harvesting takes place 15 days after. 8. Vegetative cycle: Tea leaves are ready for harvesting after 2 years and half. 9. Harvesting, conditioning and storage:  Harvesting ready and mature leaves after 7 to 15 days  The output is 3.5 to 7.5 tons per ha, i.e 0.7 to 1.5 tons of dry leaves per year and per ha.  After factory processing, dry tea is conditioned in special and moisture-proof packing. 2.11.2 Green leaf production The average green leaf production was 7000 kg/ha in 2009 and the plantations in marshland produced higher yield than hillside. The average yields are generally low as it can reach 15 700kg/ha and none of the tea estates achieves such yield. There are significant differences in productivity levels among various tea factories. The privately owned factory Sorwathe achieves the highest productivity of 11000kg/ha. It is fair to assume that productivity levels will increase within a privatized tea sector (Minagri, 2009).  21 2.11.3 Location of tea production units in Rwanda Rwanda tea is planted on hillsides at high altitude (between 1,900 and 2,500 m), and on well drained marshes at an altitude of between 1,550 and 1,800 m. Tea is grown on 11 estates located in three province (OCIR-THE, 2009). Figure 1: Location of tea production units in Rwanda (source: OCIR-THE) 2.11.4 Tea farmer organization in Rwanda There are different forms of tea farmer organizations functioning in Rwanda. Recent statistics show that there are 13 established tea farmer organizations presently in active operations. The total membership of these organizations is 30,334. These organizations command a total land area of 8 600 ha. The first organization was formed in 1964 in Rushaki-Bungwe in Gicumbi districts. It was named Coopthe Mulindi with 1 000 members. This cooperative was set up initially to supply scarce labour for the estate and later with development of smallholder tea. It was reorganized to supply green leaf to Mulindi factory. The two most recent tea smallholder organizations are COTHENYA in Nyaruguru district supplying green leaf to Mata tea factory and ATP in Rubavu district in western province which  22 supply green leaf to Pfunda tea factory. The former has a member of 1 580 with a total farming area of 361 ha while ATP has 2204 members on 778 ha (www.rwanda tea.com). Note that OCIR-The became NAEB. 2.11.5 Major challenges to tea sector Tea sector is facing challenges that affect both quality and quantity of green leaves. The main challenges are: i. Inadequate capacity of tea farmers to maintain structures like drainage systems, roads, leaf collection hangars, inadequate skills and equipment in tea cooperatives ii. The tea green leaf producers are not remunerated for the quality of leaf delivered to the tea factories. iii. Pluckers are not adequately remunerated for the critically important harvest work done iv. Tea farmers do not yet have sufficient capital funds to invest in fertilizers and transport, which support and promote quality and quantity production v. Lack of information on status of tea pest and disease due to inadequate research. vi. Absence of basic public infrastructures for connecting the new tea factories