Unit 6: Production Technology of Plantation Crops

I. Orientation — Principles of Plantation-Crop Production

Plantation crops are perennial commercial crops cultivated mainly in tropical and subtropical regions, commonly on estates or specialized farms. Their profitability depends on long-term field establishment, climate-specific management, skilled harvesting, and careful primary processing because the harvested produce often requires curing, fermentation, drying, or industrial extraction before marketing.

A. Plantation-crop production framework

The production system links ecological suitability with sustained yield, quality, and economic life.

• Perennial character: Tea, coffee, cocoa, cashewnut, and rubber remain productive for several decades; establishment decisions therefore have long-term consequences.
• Climate dependence: Rainfall distribution, temperature, humidity, altitude, shade, and wind strongly influence growth and product quality.
• Planting material: Seedlings, clones, grafts, or budded plants must be selected for yield, quality, stress tolerance, and resistance to major pests and diseases.
• Plantation layout: Contour planting, terracing, drainage, windbreaks, shade regulation, and cover crops conserve soil and reduce erosion.
• Canopy management: Pruning, training, tipping, centering, or branch regulation maintains a convenient harvesting surface and balances vegetative and reproductive growth.
• Nutrient management: Fertilizers are generally applied in split doses based on crop age, expected yield, soil tests, and nutrient removal.
• Harvesting standard: Maturity and plucking or tapping method determine both yield and processing quality.
• Primary processing: Tea leaves are manufactured, coffee berries are pulped or dried, cocoa beans are fermented, cashew nuts are roasted or steamed, and rubber latex is coagulated or concentrated.
• Sustainability: Mulching, recycling of crop residues, integrated pest management, soil-cover maintenance, and efficient water use protect long-lived plantations.

II. Tea — Production of Tender Shoots for Beverage Manufacture

Tea is obtained from the tender shoots of Camellia sinensis (family Theaceae), a perennial evergreen shrub originating in the China–Assam region. Commercial fields are maintained as low, continuously plucked bushes rather than allowed to develop into trees.

A. Tea

Tea production aims to maintain a broad, healthy plucking table that continuously supplies tender shoots of acceptable biochemical quality.

• Types and regions:
  • China type: C. sinensis var. sinensis has small leaves and relatively greater cold tolerance.
  • Assam type: C. sinensis var. assamica has large leaves and is adapted to warm, humid conditions.
  • In India, major regions include Assam, Darjeeling, the Nilgiris, Kerala, and parts of Karnataka.
• Climate: A humid climate, about 18–30°C, well-distributed rainfall near 1,500–2,500 mm, and high atmospheric humidity favour shoot growth. Drought, frost, and waterlogging reduce yield.
• Soil: Deep, well-drained, acidic soils rich in organic matter are preferred; an approximate pH of 4.5–5.5 promotes nutrient availability suited to tea.
• Propagation: Seeds may be used, but single-node or internodal cuttings from selected clones produce uniform plantations. Rooted cuttings are raised under nursery shade and hardened before planting.
• Planting: Bushes are planted in contour rows on slopes, commonly at close spacing sufficient to develop a continuous hedge. Shade trees and grasses on risers help moderate temperature and erosion.
• Nutrition and water: Nitrogen is the principal yield nutrient because the harvested product is vegetative growth. Nitrogen, phosphorus, and potassium are supplied in split applications; irrigation or mulching sustains flushing during dry periods.
• Training and pruning:
  • Centering and tipping: Removal of the main stem and repeated tipping promote lateral branches and establish a plucking table around 60–75 cm high.
  • Pruning cycle: Periodic light or medium pruning removes unproductive wood, renews shoots, and keeps bushes within plucking reach.
• Plucking: The standard fine pluck is “two leaves and a bud.” Coarser plucking raises bulk yield but lowers quality. Plucking rounds may occur roughly every 7–15 days, depending on shoot growth.
• Manufacture:
  1. Black tea: Withering → rolling or CTC maceration → enzymatic oxidation → firing → grading.
  2. Green tea: Heating or steaming first inactivates oxidative enzymes, followed by rolling and drying.
• Protection: Blister blight, red spider mite, tea mosquito bug, and root diseases require sanitation, canopy aeration, resistant material, monitoring, and need-based control.

III. Coffee — Production and Processing of Ripe Coffee Berries

Coffee is prepared from seeds of Coffea species (family Rubiaceae). Coffea arabica produces high-quality, mild coffee, while C. canephora—robusta—is generally more vigorous, heat-tolerant, and productive.

A. Coffee

Coffee production integrates regulated shade, blossom irrigation, selective berry harvest, and rapid post-harvest processing.

• Climate and elevation:
  • Arabica: Performs best under cooler conditions, commonly around 15–25°C and at higher elevations.
  • Robusta: Prefers warmer, humid conditions, commonly around 20–30°C and at lower elevations.
  • Rain followed by a dry period supports flower-bud development; showers or irrigation then trigger synchronized blossoming.
• Soil and shade: Deep, friable, well-drained loams rich in organic matter are suitable. Two-tier shade, using temporary and permanent shade trees, protects plants from heat, wind, and moisture loss.
• Propagation: Arabica is usually seed-propagated because it is largely self-fertile; robusta may be propagated vegetatively to preserve superior cross-pollinating clones. Nursery seedlings are planted with the ball of earth intact.
• Training:
  • Single-stem system: The main stem is topped at a manageable height, and unwanted vertical suckers are removed.
  • Handling and pruning: Old, weak, crossing, and diseased branches are removed to improve light penetration and renew bearing wood.
• Water and nutrition: Blossom irrigation after the dry period promotes flowering; backing irrigation supports fruit set. Fertilizers are split around pre-blossom and post-monsoon growth, while lime is used where excessive acidity requires correction.
• Harvesting: Selective picking of fully red, ripe berries gives better quality than stripping mixed green, ripe, and overripe fruits. Arabica generally matures earlier than robusta.
• Processing:
  1. Wet method: Pulping → mucilage fermentation → washing → drying produces parchment coffee and usually a cleaner cup.
  2. Dry method: Whole berries are sun-dried and hulled to produce cherry coffee.
• Protection: Coffee leaf rust is especially important in arabica; white stem borer, berry borer, and black rot are managed through resistant cultivars, regulated shade, timely harvest, sanitation, trapping, and approved plant-protection measures.

IV. Cocoa — Production of Fermented Beverage and Confectionery Beans

Cocoa, Theobroma cacao (family Malvaceae), is a small evergreen tree native to tropical America. Its seeds supply cocoa solids and cocoa butter, but characteristic chocolate flavour develops mainly during fermentation and roasting.

A. Cocoa

Successful cocoa production requires a warm, humid, shaded environment and correct fermentation of fully mature beans.

• Climate: Temperatures near 21–32°C, high humidity, and annual rainfall around 1,500–2,500 mm are favourable. Strong winds, prolonged drought, and water stagnation are harmful.
• Cropping system: Cocoa is commonly grown as an intercrop under coconut or arecanut because their canopy provides partial shade. Excessive shade reduces flowering, whereas insufficient shade causes leaf scorching and moisture stress.
• Soil: Deep, fertile, well-drained loams with high organic matter are preferred. Drainage channels are essential in high-rainfall plantations.
• Propagation: Seeds are sown soon after extraction because they lose viability rapidly. Superior trees may be multiplied by budding, grafting, or rooted cuttings to obtain uniform yield and bean quality.
• Planting and canopy management: Seedlings are established under temporary shade. A jorquette—where the main stem divides into fan branches—is maintained, and chupons arising below it are removed. Diseased, crowded, and low branches are pruned.
• Pollination and bearing: Tiny flowers arise directly on the trunk and older branches, a condition called cauliflory. Small midges are major pollinators; only a small proportion of flowers develop into pods.
• Nutrition and irrigation: Organic manure and split NPK applications sustain continuous flowering and pod filling. Mulching and irrigation are particularly valuable during dry months.
• Harvesting: Mature pods show a characteristic colour change and are cut carefully without damaging flower cushions. Pods are opened without cutting the beans.
• Fermentation and drying: Beans with adhering pulp are fermented in heaps, baskets, or wooden boxes for about 5–7 days with periodic turning. Fermentation kills the embryo, reduces bitterness, and forms flavour precursors; beans are then dried to roughly 6–7% moisture.
• Protection: Black pod, stem canker, vascular-streak dieback, mealybugs, and pod borers require field sanitation, shade regulation, drainage, removal of infected pods, and integrated control.

V. Cashewnut — Orchard Production of Nuts and Cashew Apples

Cashewnut, Anacardium occidentale (family Anacardiaceae), is a drought-tolerant evergreen tree native to Brazil. The true fruit is the kidney-shaped nut; the swollen, juicy cashew apple is an accessory fruit.

A. Cashewnut

Cashew production depends on elite grafts, open canopy management, effective flowering, and safe processing of the shell-enclosed kernel.

• Climate: Warm tropical conditions around 20–35°C and a distinct dry period during flowering and fruit development are favourable. Rain during flowering interferes with pollination and encourages diseases.
• Soil: Cashew tolerates lateritic, sandy, and relatively poor soils but performs best in deep, well-drained soil. Waterlogging and severe frost are unsuitable.
• Propagation: Seedling orchards are highly variable; softwood grafting using scions from elite mother trees is preferred. Grafted plants bear earlier and produce more uniform nuts.
• Planting: Regular spacing is commonly about 7–8 m, while high-density planting may begin at closer spacing followed by canopy regulation or thinning. Pits are filled with topsoil and organic manure.
• Training and pruning: Plants are trained to a single stem for approximately the first 0.75–1.0 m. Basal shoots, criss-cross branches, deadwood, and excessively crowded growth are removed after harvest.
• Nutrition and interculture: Farmyard manure and age-based NPK doses improve growth and yield. Legumes, pineapple, or other short-duration crops may be intercropped before the cashew canopy closes.
• Flowering and harvest: Terminal panicles bear male and bisexual flowers. Mature nuts detach with the apple and are collected from the ground; nuts are separated promptly and sun-dried.
• Processing and products: Nuts are steamed or roasted, shelled, kernels dried, peeled, graded, and packed under moisture-proof conditions. Cashew nut shell liquid contains industrial phenolic compounds, while apples can be processed into juice, syrup, or fermented products.
• Protection: Tea mosquito bug damages tender shoots, panicles, and young nuts; stem-and-root borer can kill trees. Orchard sanitation, removal of infested tissue, canopy aeration, and stage-based integrated control are essential.

VI. Rubber — Latex Production through Controlled Tapping

Natural rubber is obtained mainly from Hevea brasiliensis (family Euphorbiaceae), a tree native to the Amazon region. Latex flows through laticifer vessels in the bark and is processed into sheets, crepe rubber, concentrates, or technically specified rubber.

A. Rubber

Rubber production seeks sustained latex yield without excessive bark consumption or physiological exhaustion of the tree.

• Climate: Warm conditions around 25–35°C, rainfall near 2,000 mm or more, high humidity, and minimal strong winds favour growth. Prolonged drought reduces latex flow.
• Soil: Deep, well-drained, acidic loams or lateritic soils are suitable. Terraces, contour drains, and leguminous cover crops reduce erosion on slopes.
• Planting material: Seedlings are mainly used as rootstocks. High-yielding clones are multiplied by brown or green budding, producing budded stumps or polybag plants with uniform characteristics.
• Planting and immature care: Plants are spaced to allow canopy development and tapping access. Mulching, weed control, cover crops, fertilizer application, and wind protection promote rapid attainment of tappable girth.
• Tapping maturity: Trees are generally opened when a specified proportion of the stand reaches about 50 cm trunk girth measured near 1.2–1.25 m above the bud union.
• Tapping system: A sloping cut severs latex vessels without injuring the cambium. A notation such as S/2 d2 means a half-spiral cut tapped once every two days. Correct depth, angle, frequency, and bark consumption determine plantation life.
• Latex collection: Latex flows along the cut into a channel and cup. Ammonia may be added when latex must remain liquid; uncontrolled microbial activity causes premature coagulation.
• Processing:
  • Ribbed smoked sheets: Latex is strained, diluted, coagulated with formic or acetic acid, rolled into sheets, and smoke-dried.
  • Other forms: Field coagulum may become crepe or block rubber, while centrifugation produces concentrated latex.
• Protection and disorders: Abnormal leaf fall, powdery mildew, pink disease, root diseases, wind damage, and tapping-panel dryness affect productivity. Resistant clones, sanitation, balanced tapping, rain guards, and recommended fungicidal or cultural measures reduce losses.