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Science of Tea Technology
About the Editors
Dr. P.S. Ahuja, FNA Director CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific & Industrial Research) Post Box No. 6 , Palampur (H.P.)- 176061, India. E-mail: [email protected]; [email protected]
Dr. Arvind Gulati Chief Scientist CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific & Industrial Research) Post Box No. 6, Palampur (H.P.)- 176061, India. E-mail: [email protected]
Dr. R.D. Singh Chief Scientist CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific & Industrial Research) Post Box No.0000 6, Palampur (H.P.)- 176061, India. E-mail: [email protected]
Dr. R.K. Sud Principal Scientist CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific & Industrial Research) Post Box No. 6, Palampur (H.P.)- 176061, India. E-mail: [email protected]
Dr. R.C. Boruah, FNA Sc Outstanding Scientist CSIR-North East Institute of Science & Technology (Council of Scientific & Industrial Research) Jorhat- 785006, Assam. E-mail: [email protected]
Science of Tea Technology
Editors
Dr. P.S. Ahuja, Dr. Arvind Gulati, Dr. R.D. Singh, Dr. R.K. Sud CSIR-Institute of Himalayan Bioresource Technology (IHBT), Palampur (H.P.), India
Dr. R.C. Boruah CSIR-NEIST, Jorhat (Assam)
Published by:
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© CSIR-Institute of Himalayan Bioresource Technology, Palampur (H.P.), India (Website: www.ihbt.res.in), 2013
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ISBN: 978-81-7233-831-2 eISBN: 978-93-87741-08-9 Cover page designed by: PS Ahuja, Pabitra Gian and Mukhtiar Singh (CSIR-IHBT, Palampur, H.P.)
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PREFACE
Tea is the most popular non-alcoholic drink among masses in the beverage sector, gaining prominence for its nutraceutical attributes in the health sector and an employment generating source in the social sector. It is a source of revenue to many developing countries viz., Sri Lanka, Kenya, India, China and Turkey. Tea cultivation has spread in 3.43 m ha in 34 odd countries globally. China, India, Sri Lanka, Kenya, Indonesia and Vietnam are the major players accounting for nearly 83-85% of each i.e. area, production and export. Crop product-ivity is rising and new areas are brought under tea in traditional and non-traditional regions. In the last decade, China expanded about 0.58 m ha of plantations, an area equal to the present acreage under tea in India. In India, expansion has been mainly by the small growers and tea has become the livelihood to 1 lakh 57 thousands of such growers who command 26% of the national production. But as a whole the earlier strength of tea being labour intensive is now transforming into the biggest weakness due to rise in the socio-economic status of the society and even countries like Kenya, Malawi, Ethiopia and Sri Lanka are facing the problem of declining farm work force. In Japan, a variety of farm machines have been introduced to cope up the labour shortage and cut down the labour expenses. Agrotechnologies for farm mechanization are known and need to be evaluated and adopted. At the processing front, new machinery with precise and controlled steps of manufacture are being introduced. A pre-withering machine, introduced by CSIR-IHBT in association with M/s. Mesco Equipment is a disruptive concept in tea processing that requires attention of the tea manufacturers. Beside traditional black and green tea, high value oolong tea, white tea, yellow tea and speciality teas are being introd-uced and marketed. Furthermore, tea processing is also undergoing process of transformation due to advancement in tea biochemistry. Over the past decade many scientific studies have focused on tea properties for its purported health benefits and evidences are now convincing that tea is a health drink because of its multiple preventive and therapeutic effects. Various diversified health care products e.g. theaflavins, polyphenols, theanine and decaffeinated tea are getting a niche identity in the tea market. Fast teas viz., Ready-to-Drink teas, tea concentrates, instant tea, tea based juices, tea wines are now
vi Science of Tea Technology
popular. Advances in the field of biotechnology and molecular biology has revolutionised the tea improvement programmes. Under a joint project, different Indian premier institutes have finger-printed the entire tea germplasm and shortlisted the core collections for adding efficiency to breeding programmes in the future. Advances in elucida-ting tissue culture technology, catechins biosynthetic pathway, development of molecular markers to identify adulterants in tea and major plant responses during winter dormancy and drought response, efficient protocols for somatic embryogenesis for the production of synthetic seeds and protocols for development of transgenic tea plants will have their impact in near future. CSIR-IHBT has been engaged in applied, fundamental and high science cutting edge technology ever since its establishment in the year 1983-84 and has contributed immensely for the global tea industry. This book provides information on some of the latest aspects of tea husbandry, physiology, biochem-istry, manufacture and biotechnology in its chapters. Chapter-wise highlights are highlighted hereunder:
1. History of Tea in India (Brajinder Singh and R.K. Sud)
Tea was discovered by the Chinese Emperor Shen Nung in 2737 BC and thereafter became a popular beverage and health drink in China. It was introduced to Japan in the early part of eighth century but the rest of the world was ignorant about tea until about middle of seventeenth century. Interesting stories of origin of the tea plant and how the British introduced the Chinese tea in India and subsequently discovered an India tea variety in Assam jungle have been described. Tea was introduced to India in 1774 by a Botanist, Mr. Robert Fortune. Later on, in 1823 a native species of tea plant growing wild in Assam was discovered by Major Robert Bruce. Commercial culti-vation began on 12 February, 1839 when the world’s first privately owned tea company – the Assam Tea Company – was established at Jorhat, Assam with the directives from British Parliament. Today majority of tea plantations around the world are based upon Assam type tea. A detailed account of setting up and development of tea plantations in different parts of India with specific account of Kangra valley in Himachal Pradesh, which is lesser known distinctive flavoured tea, has been portrayed.
2. Genetic Improvement of Tea (S. Singh et al.)
Like any other agricultural crop, availability of high yielding quality clones with greater tolerance to pest, diseases and environm-ental stresses is a basic need for sustaining production levels. With
Preface vii
the introduction of improved clonal cultivars, the tea industry has shown significant and sustained progress over the years. However, at present tea production has stagnated and is beset with new problems which are widespread or region specific. Improvements in terms of quality and productivity can only be achieved through development of new varieties. Therefore, tea breeding programs in the world need to be given impetus through germplasm appraisal, use of molecular markers associated with the traits of interest for early selection in segregating progenies, redefining parameters constituting plant ideotype and utilizing tools of phenomics for evaluating plant responses to environmental variations and stresses. Descriptive details of all these parameters are highlighted.
3. Tea Applied Genomics: Utilizing Genetic Variability and Current Genomic Tools to Enhance Productivity (R.K. Sharma et al.)
Genetic improvement of tea involves identification, characteri-zation, evaluation, domestication, maintenance and utilization of germplasm for development of superior plant material. Conventional breeding programme in tea, however, limited by long-gestation period, out-breed nature and self-incompatibility. This chapter links status of emerging molecular genomic information that can expedite the genetic improvement in tea and hence increase the productivity. This will provide a background of possibilities for modern tea breeding together with some current efforts for development of sequence based markers and links genetic diversity of existing gene pools, identification of diverse parental groups, efficient phenotyping to support operational breeding. Preliminary attempts on quantitative trait locus (QTL) mapping in tea were also reviewed and prospective is also provided to exploit the power of association genetics to dissect quantitative traits. Challenges and opportunities owing to advent of next generation sequencing (NGS) technologies to generate genome wide makers and to integrate genomic information into directional selective breeding are also discussed.
4. Tea Propagation (R.K. Sud)
One of the reasons for the stagnation of the tea production in India is that majority of the plantations have crossed their peak production phase and therefore call for replanting and new planting in a phased manner. Overall requirement of nursery tea plants for new planting, replanting and infilling and interplanting is enormous as presently, nearly 12,000 plants are planted in one hectare area. Both
viii Science of Tea Technology
clonal and seed-raised plants are needed to cope up the climatic, environmental and biotic stresses. Nursery techniques involve several steps starting from appropriate soil to erecting nursery structure, suitable seed/cutting to hardening of the raised plants. Adoption of recent advances in each step is necessary to grow plants in the shortest possible time with a minimum of losses. Growing composite plants with scions-cuttings of high yielding clones grafted on hardy rootstock-cuttings is gaining momentum. The Chapter provides latest information on all aspects of plant propagation.
5. Tea Seed and its Biology (Amita Bhattacharya et al.)
In tea, biclonal and polyclonal seeds are produced through hybridization between two or more superior clones. These play an important role in the selection of new varieties. The complete reproductive cycle from flower initiation to anthesis and seed maturity as well as the physiology of seed development involving endogenous changes in hormone and subsequent germination pattern have been discussed. Tea seeds are recalcitrant and cannot withstand desiccation and dehydration. Thus, the storage of seeds is unconventional and requires the maintenance of appropriate moisture levels. Seeds are also the source of saponins, edible oil, cakes, cosmetics, insecticides, molluscicides etc.
6. Young Tea Management (R.D. Singh)
This chapter discusses raising of young tea plantation for early canopy cover to facilitate manual or mechanical harvesting of tea shoots. It deals with time and method of pruning, bending and pegging, tipping, and use of plant growth regulators as pruning agents in young tea. Method and importance of mulching as well as intercropping in young tea has been also discussed.
7. Tea Pruning (R.K. Sud)
Pruning is referred to as a “necessary evil” in tea parlance as it causes severe crop loss on the year and involves extra expenditure. Yet it is a fundamental need to maintain vegetative regeneration and sustained productivity. Appropriate pruning cycle i.e. pruning with different skiffing-types in different years, is a key to strike a balance with yield and quality as per the market needs. Understanding of physiological basis of pruning is imperative to rationalise source-sink relationship and formulate the pruning cycle. Time of pruning, linked with maximum root starch reserve period, is the most important factor for minimising mortality and achieving better post-prune recovery.
Preface ix
Interaction of pruning times with insect-pests and diseases is another significant factor. Rejuvenation pruning may be adopted as a short measure to revive the aging plantation but it cannot substitute replanting especially in Assam type tea. Dilapidated china hybrid tea plantations have been successfully revived to the point of maximum productivity.
8. Tea Plucking (R.K. Sud)
Plucking, apparently refers to removal of the apical shoots as a crop. In fact, it is a much wider and deeper subject, having implica-tions of productivity and quality of crop, garden and factory manage-ment, marketing and economics and social dimensions. Principals of the plucking are based on physiology of tea bush. Establishment of plucking table, tipping measures, system of plucking etc. are guided by photosynthetic efficiency of the leaves and source-sink relationship. Pruning, tipping and plucking are inter-related operations in tea and severity of one is compensated by leniency of the other to maintain the productivity. A comprehensive information on shoot growth, tipping measures, systems and standards of plucking in relation to physio-logical, environmental and biochemical parameters have been discus-sed. Keeping the chinary planting material of Kangra/Darjeeling gardens on the forefront, guidelines have been given in the chapter for management of different flushes and harvesting quality crop.
9. Mechanization in Tea (K.K. Singh)
Due to significant rise in socio–economic status, per capita income and education status, the farm workers are not readily available for tea plantations. Continuous labour wage hike is another deterrent in the economics of tea plantation, compelling to look for alternatives. The mechanization of farm operations in tea plantations across the tea growing countries has evolved as a way to tackle the labour shortage particularly for harvesting of leaves. Different machines of the varying capacities and types have been developed and are in use. New models are being developed to meet the specific needs. In this chapter, tea farm operations that can be mechanized viz., fertilizer application, chemical spraying, mechanical weed control, pruning and skiffing, plucking, bush uprooting and other operations have been discussed to mitigate labour shortage and make tea growing a sustainable venture.
10. Plant Nutrition (R.D. Singh)
Fertilizer is an expensive input in tea production, accounting up to 15-25% of total cost of cultivation. This chapter deals with
x Science of Tea Technology
deficiency of important nutrient elements viz., N, P, K, Ca, Mg, S, B, Mn and Zn. Time, sources and method of application of different fertilizers for supplying major and trace elements including Cu, Al and selenium in tea are discussed. This chapter also deals with influence of the fertilizers on tea yield and quality of made tea, age of tea plantation and fertilizer use, effect of mulching on nutrient uptake, and leaf analysis for diagnosis of plant nutrient deficiency.
11. Water Management in Tea (K.K. Singh)
Tea is a perennial crop requiring high amount of water during growth period but in most of the area tea plantations are rainfed. Rainfall, which often occurs most evenly in rainy season, also leads to deficit in dry periods. Irrigation is essential not only for producing higher crop but also in reducing seasonal dormancy during deficit and cold dry periods. Both over irrigation and under irrigation affect the soil moisture status and environment and the projected benefit might result into loss. So an optimum quantity of water should be applied at proper time. In designing irrigation or drainage system, it is essential to determine tea crop water requirement, which depends mainly on weather data relating to crop on temporal basis. The meteorological observation on evaporation and rainfall for sufficient period can be used for estimating crop water requirement, which can be replenished by border irrigation system on mild slopes. Sprinkler irrigation system (pressurized irrigation) can be used for water application in undulating and high slope area. The excess water from precipitation, over irrigation, seepage may be drained off by different surface and sub-surface drainage systems. Effective irrigation and drainage in tea with relevant technologies should make tea management a lucrative and profitable venture.
12. Disease Management in Tea (Arvind Gulati and R.K. Sud)
Like any other cultivated crop, tea is prone to attack by several diseases, causing heavy crop loss. The diseases attack various parts of the bush, and result in defoliation, debilitation and even mortality of the bush. Fungal organisms account for most of the diseases, apart from a few diseases caused by bacteria, viruses, and algae. In this chapter common diseases of economic importance and their management based on the latest information are briefly described.
13. Managing Weeds in Tea (R.D. Singh)
Weed control in tea is the second most expensive input after plucking. In tea plantations, grasses generally predominate the weed
Preface xi
flora followed by broad-leaf weeds. Weed competition is critical during warm and humid weather conditions and is severe in young and pruned tea sections. Delay in weeding after critical period adversely affects branching, growth and yield of young tea. In mature tea, weeds often interfere plucking, pruning and fertilizer application thereby reduce efficiency of farm workers. In general, weeds cause 10-25 % yield loss in tea depending on severity and type of weeds and pruning of tea plantation.
This chapter also deals with reasons for weed infestation in tea, weed management by physical, chemical and biological methods in young and mature tea sections and in pruned tea. It reveals that use of herbicides like glyphosate, 2,4-dichlorophenoxy acetic acid, paraquat and simazine is common practice for effective weed management in tea plantations. Mulching with straw, tea pruning-litter or black low density polyethylene sheet is also effective for weed control in mature as well as young tea planted on slopes.
14. Insect and Mite Pests of Tea and their Management (Gireesh Nadda et al.)
Tea provides a relatively steady microclimate and food supply to insect and mite pests. Each tea growing country has its own distinctive pests, however, several of them are common. Globally, 1031 species of arthropods are associated with tea monoculture. The plant is attacked by nearly 250 insect species causing serious damage to productivity and quality. Most of the tea pests are seasonal; some attack only during dry season while a few are abundant in wet weather. Among the various pests, tea mosquito bug, mealy bug, thrips, aphids, scale insects, leaf hoppers, tortricids, leaf rollars, borers, looper caterpillar, mites, termites and nematodes cause severe loss of crop yield. However, the magnitude of pest infestation varies based on factors like altitude, climate and cultural practices. Weeds, a major component of the tea ecosystem serve as alternative hosts for pests as well as a refuge for natural enemies. The concept of pest control has undergone a considerable change over the past few decades. Rising concern about the pesticide residue in made tea, its toxicity hazards to consumers, the cost of pesticides and their application have necessitated a suitable planning which will ensure a safe, economic as well as effective pest management in tea. This chapter contains information on the major and minor pests of tea, damage that they cause and appropriate control methods to combat the pest population in the field for sustainable crop production.
xii Science of Tea Technology
15. Pesticide Residues in Tea (Yogesh B. Pakade and Adarsh Shanker)
Tea is an important export commodity and keeping it completely free from pesticide residues is desired. However, it is impractical in view of the serious pest and disease problems where chemical pesticides have to be applied for their management. As tea is subjected to infusion prior to consumption, pesticide residues in tea and its transfer in brew must be monitored prior to marketing. Various international authorities have regulated the use of pesticides by fixing maximum residues levels (MRLs) for commercial purposes. The factors involved in the degradation of pesticides on tea plant are discussed in this chapter. This chapter also explores the fate of pesticide during manufacturing processes as well as during infusion of tea. Alternative extraction methodologies are discussed for pesticide residue analysis in tea which play an important role.
16. Organic Tea Farming (R.D. Singh)
In tea plantations, use of agrochemicals is substantially higher than field crops. Consequently, threat from residual effects of pesticides applied in tea is also high, especially in made tea. This chapter deals with the present status and scope of organic tea farming involving cultural practices like planting disease free seed-stocks, using organic mulch materials, organic manures and bio-fertilizers, recycling farm residues/wastes, and plant protection by bio-pesticides.
17. Plant Physiological Approaches for Enhancing Productivity in Tea (S.K. Vats and P.K. Nagar)
The physiological basis of growth and yield in tea depends on the potential of photosynthetic process, and the rate of transfer of photosynthates to different organs. Both the processes that also decide the operational physiological range are dependent on the genotypic and environmental factors. Often, the interplay of environmental parameters become location specific and assumes greater manage-ment role. For instance, shade that also influences canopy tempera-ture and to some extent soil moisture has a greater significance in tropical than temperate areas. Optimal performance in tea, therefore do not depend on light, temperature or soil moisture conditions per se but the interaction of it. The role of nutrients, irrigation during dry period, and application of growth regulators have quite well been exploited to improve yield and tackle winter dormancy in tea in areas away from equator. Good Management Practices, thus need to account for these.
Preface xiii
18. Tea Biochemistry (Ashu Gulati)
The chapter concentrates on the nature of the non-volatile compounds such as polyphenols and catechins, and their oxidized products viz., theaflavins and thearubigins, theanine, lipids, caffeine and the factors affecting their concentration in the tea shoots. In tea, volatile components though present in minute quantities, yet play pivotal role in the flavoury teas. These volatile compounds are either liberated from their glycosidic precursors by hydrolysis during manufacture, or are formed by thermal degradation or oxidative degradation of fatty acids and carotenoids. The hydrolysis of volatile flavour component precursors is mediated by β-glucosidases.
19. Tea Manufacture (Ashu Gulati)
Teas are classified into three main categories according to the degree of fermentation during manufacturing: non-fermented (green and white teas), partially fermented (oolong tea), and fully fermented (black tea). Activation or non-activation of the enzyme polyphenol oxidase present in tea leaves is the key player for processing of these tea types. Genetic material of the shoot, the environmental conditions under which it grows, and process conditions during manufacturing determine quality of tea. In traditional factories, human judgement plays a vital role in the standardization of process parameters in the made tea. A preconditioning machine developed by CSIR-IHBT based on the concept of physical and chemical wither in black tea manufac-ture has demonstrated considerable reduction in withering time with improvement in tea quality. Recently, fuzzy logic based system being tried to automate the tea processing. Chemical sensors using metal oxides are being developed for optimizing the fermentation step.
20. Diversified Tea Products (H.P. Singh et al.)
The natural nutrceutical compounds in tea leaves rich in antioxidant activities are the host of these attributes. There is a spurt in research activities the world over for the development of various diversified tea products. CSIR-IHBT has also developed some tea based products such as ready to drink black and green tea concen-trates, tea wines, tea polyphenols free from caffeine, amino acids and soluble sugars, high grade bio-processed theaflavins which have potential in the world market. Modern trend exhibits further scope for the formulations of more exotic, fruity flavours, rich in nutrients, herbal and ethnic teas for value addition and fortification of human health.
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21. Some Recent Innovations in Tea Biotechnology (Anil Sood et al.)
There was an urgent need to characterize the existing tea germplasm and molecular markers are developed to categorize the accessions. For effective multiplication of superior clones, protocols for micropropagation are now available. Major strides are made towards improvement of tea quality and yield by dissecting the catehcins biosynthesis pathway, winter dormancy and drought responses. Plant improvement using molecular markers and also by genetic manipu-lations and transformations are discussed and now standardised for application in tea.
This book is a source of latest information on tea. All the chapters have been well compiled with dedication and sincerity and authors own the authenticity of the information. I hope the book will be useful to variety of users including students, teachers, researchers, planners and policy makers as well as the tea information curious people. The editorial board is indebted to Prof. Sudhir K. Sopory, Vice Chancellor of Jawaharlal Nehru University, New Delhi and Research Council Chairman of the CSIR-IHBT who was the motivating force behind the publication of this book. The commitment and hard work of Sh. Mukhtiar Singh, Library Officer of CSIR-IHBT in compilation of the book deserves special mention for which the editors are deeply indebted. Thanks are also due to Dr. Rakesh Kumar for reviewing of the text of the chapters on tea husbandry. Authors have taken the liberty to access to the research findings and other required information from India and abroad, which have been duly referred.
(P.S. Ahuja) Chief Editor
CONTENTS
1. History of tea in India………Brajinder Singh and R.K. Sud 1-21
Introduction 1 Tea in Assam 2 Tea in Darjeeling 4 Tea in South India 6 Tea in Uttarakhand 7 Tea in Kangra valley 8
2. Genetic improvement of tea…..S. Singh, Ashok Kumar, S. Karthigeyan and P.S. Ahuja
22-63
Introduction 22 Origin and distribution 23 Germplasm resources and conservation 24 Problems of tea production and breeding 27 Breeding objectives 28 Inheritance of yield and quality traits 30 Breeding approaches for genetic improvement of tea 30 Future strategies 51
3. Tea applied genomics: utilizing genetic variability and current genomic tools to enhance productivity.….. R.K. Sharma, Pankaj Bhardwaj, Rahul Kumar, Himanshu Sharma and P.S. Ahuja
64-87
Background 64 Population and genetic diversity 67 Assessment of gene flow among the gobal tea cultyivations
other than centre of origin 72
DNA fingerprints for unique identification 73
xvi Science of Tea Technology
Establishment of genetic uniformity 76 SSR marker development 77 Genome mapping and quantitative trait loci (QTLs) mapping 80 Opportunities and prospects 82
4. Plant propagation…..R.K. Sud 88-120
Introduction 88 Requirements 90 Nursery structure 95 Vegetative propagation 98 Raising seedlings 109 Centring of nursery plants 110 Raising grafted plants 112
5. Tea seed and its biology…..Amita Bhattacharya, R.K. Ogra, Om Prakash and R.S. Shekhawat
121-133
Introduction 121 Biclonal and polyclonal seeds 122 Flowering and pollination 122 Fruit and seed development 124 Seed bearing pattern 126 Seed morphology 127 Germination 127 Physiology of tea seeds 128 Storage 129 Uses 130
6. Young tea management……R.D. Singh 134-143
Young tea raising 134 Mulching 137 Intercropping in young tea 139 Root growth in young tea 140 Tillage 140 Water requirement 140
7. Tea pruning……R.K. Sud 144-180
Definition and importance 144 Objectives of pruning 146
Contents xvii
Types of pruning 146 Types of skiffing 151 Level and time of pruning and skiffing 153 Pre-requisites for pruning 157 Pruning and biochemical changes 160 Pruning and hormones 161 Pest infestation in relation to pruning 161 Post pruning care 163 Pruning cycle 164 Other management practices during pruning season 166 Development of unproductive and abandoned tea plantations 168 Future area of work 174
8. Tea plucking…..R.K. Sud 181-219
Definition and importance 181 Basics of plucking 182 Tipping 186 Shoot growth and crop distribution 189 Systems of plucking 192 Standards of plucking 196 Plucking interval 198 Management of different flushes in kangra 204 Yield vs quality 206 Harvesting quality crop 206 Future lines of work 210
9. Mechanization in tea…..K.K. Singh 220-235
Introduction 220 Engine operated sprayers 221 Aeroplanes and helicopter sprayer 221 Tea plucking machine 221 Shear harvesting 222 Motorized harvesting can be classified as follows 222 Self –propelled machines 229 Mechanization of pruning 230 Mechanical up rooting of tea 232 Bio-composting 232
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10. Plant nutrition….R.D. Singh 236-263
Deficiency of important nutrient elements in tea 237 Use of Fertilizers 238 Nitrogen 238 Phosphorus 241 Potassium 242 Calcium 244 Magnesium 244 Sulphur 245 Micronutrients 246 Zinc 246 Manganese 247 Copper 247 Boron 247 Aluminum 248 Selenium 248 Trace elements as chelates 248 Fertilizer and tea quality 248 Time of fertilizer application 250 Method of application 250 Plant nutrition in young tea 251 Age of plantation and fertilizer use 252 Fertilizer use and root growth 252 Mulching and nutrient uptake 252 Pruning vs fertilizer levels 253 Leaf analysis for diagnosis 253 Importance of soil testing 255
11. Water management in tea…..K. K. Singh 264-278
Introduction 264 Study of hydrological data 265 Estimation of crop evapotranspiration 265 Water management in tea 270 Irrigation in tea 271 Water application methods 272 Drainage in tea 275
Contents xix
Design discharge of open ditch 276 Design of open drains 276 Sub surface drainage 277 Lay out of drainage system 277
12. Disease management in tea…..Arvind Gulati and R.K. Sud 279-300
Leaf diseases 279 Stem diseases 289 Root diseases 291 Management strategies for primary root disease 293
13. Managing weeds in tea…..R.D. Singh 301-316
Critical period 302 Reasons for weed infestation in tea 302 Losses caused due to weeds in tea 302 Weed management 304 New herbicides 306 Quality of water and bioefficacy of herbicide solution 307 Physical and mechanical methods 307 Weed biology 310 Benefits of weeds in tea crop management 310 Economics of weed management 311 Suggested cultural practices 311
14. Insect and mite pests of tea and their management …..Gireesh Nadda, S.G. Eswara Reddy and Adarsh Shanker
317-333
Sucking pests 320 Lepidopteran pests 324 Coleopteran pests 325 Mite pests (acarina) 327 Soil pests 330 Minor pests 330
15. Pesticide residues in tea…..Yogesh B. Pakade and Adarsh Shanker
334-350
Introduction 334 Fate of pesticides 336 Fate of pesticides residue during processing 340 Fate of pesticides during infusion 342
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Methods for determination of pesticide residues 344 Mrls in tea and global trade 345 Conclusions 346
16. Organic tea farming…...R.D. Singh 351-358
Planting material 354 Manuring 354 Mulching 355 Technical efficiency 356 Scope 356
17. Plant physiological approaches for enhancing productivity in tea…..S.K. Vats and P.K. Nagar
359-376
Introduction 359 Effect of environmental factors on tea 365 Dry matter production 366 Winter dormancy 368 Dormancy and plant growth regulators 369 Plant growth regulators for crop improvement 370
18. Tea biochemistry….Ashu Gulati 377-400
Polyphenols 379 L-theanine (n5-ethyl-glutamine) 381 Caffeine 383 Lipids 386 Biogenesis of aroma during manufacture 389 Polyphenol oxidase 392
19. Tea manufacture…..Ashu Gulati 401-423
Green tea 402 Oolong tea 405 Black tea 407 Leaf preconditioning machine for withering 419 Other developments in tea technology 421
20. Diversified tea products….H.P. Singh, Brajinder Singh and Mahesh Gupta
424-429
Tea as major nutraceuticals base 425 CSIR-IHBT role in developing tea nutraceuticals 426
Contents xxi
Future trends 428
21. Some recent innovations in tea biotechnology…..Anil Sood, Madhu Sharma, Amita Bhattacharya, Sanjay Kumar, R.K. Sharma, P.K. Nagar, Om Prakash and P.S. Ahuja
430-476
Introduction 430 Tea glutamine synthetase: gene isolation, characterization
and exploration 432
Molecular diagnostics using DNA markers 434 Physiological and molecular basis of winter dormancy 435 Response of tea to drought 441 Molecular basis of catechin biosynthesis in tea 442 Tea micropropagation 446 Rooting, hardening and field transfer of tissue culture raised
plants 447
Somatic embryogenesis 452 Synthetic seeds 454 Tea transgenics 456 Conclusion 463
