1) Cultivation means production of medicinal plants or drug using prepared land.
2) The advantages of cultivation may be briefly summarized as follows:
a- It ensures quality and purity of medicinal plants. Crude drugs derive their utility from chemical
contents in them. If uniformity is maintained in all operations during the process of cultivation,
drugs of highest quality can be obtained. If the cultivated plants are kept free of weeds, the
contamination of crude drugs can be conveniently avoided.
b- Collection of crude drugs from cultivated plants gives a better yield and therapeutic quality.
However, it is a skilled operation and requires some professional excellence, if the collection of
crude drugs for market is done from cultivated plants by skilled and well experienced personnel,
the high yield and therapeutic quality of drugs can be maintained.
c- Cultivation ensures regular supply of a crude drug. In other words, cultivation is a method of crop-
planning. Planning a crop cultivation regularizes its supply and as a result the industries depending
upon crude drugs do not face problem of shortage of raw material.
d- The cultivation of medicinal and aromatic plants also leads to industrialization to a greater extent.
The cultivation of coffee and cocoa in Kerala has given rise to several cottage and small-scale
industries. The cultivation of cinchona in West Bengal has led to the establishment of the
cinchona-alkaloid factory near Darjeeling.
e- Cultivation permits application of modern technological aspects such as mutation, polyploidy and
Methods of Plant Propagation: -
Medicinal plants can be propagated by two usual methods are referred as sexual method and asexual
A- Sexual method (seed propagation): -
i. In case of sexual method, the plants are raised from seeds and such plants are known as seedlings.
ii. For propagation purpose, the seeds must be of good quality. They should be capable a high
germination rate, free from diseases and insects and also free from other seeds, used seeds and
iii. The germination capacity of seeds is tested by rolled towel test, excised embryo test, etc. The
seeds are preconditioned with the help of scarification to make them permeable to water and
gases, if the seeds are not to be germinated in near future, they should be stored in cool and dry
place to maintain their germinating power.
iv. Long storage of seeds should be avoided. Before germination, sometimes a chemical treatment is
given with stimulants like gibberellins, cytokinins, ethylene, thiourea, potassium nitrate or sodium
v. Gibberellic acid (GA3) promotes germination of some type of dormant seeds and stimulates the
Methods of sowing the seeds: -
Following methods are used for sowing seeds: -
a- Broadcasting: -
i. If the seeds are extremely small the sowing is done by broadcasting method. In this method
the seeds are scattered freely in well prepared soil for cultivation. The seeds only need
ii. If they are deeply sown or covered by soil, they may not get germinated. Necessary
thinning of the seedlings is done by keeping a specific distance, e.g. Isapgol, Linseed,
b- Dibbling: -
i. When the seeds of average size and weight, they are sown by placing in holes. Number of
seeds to be put in holes vary from three to five, depending upon the vitality, sex of the
plants needed for the purpose and the size of the plant coming out of the seeds.
ii. For example, in case of fennel four to five fruits are put in a single hole keeping suitable
distance in between two holes. In case of castor, only two to three seeds are put. In case of
papaya, the plants are unisexual and only female plants are desired for medicinal purposes.
Hence, five to six seeds are put together and after the sex of the plants is confirmed,
healthy female plant is allowed to grow while male plants and others are removed.
c- Miscellaneous: -
i. Many a times the seeds are sown in nursery beds. The seedlings thus produced are
transplanted to farms for further growth, such as cinchona, cardamom, clove, digitalis,
d- Special treatment to seeds: -
i. To enhance germination, special treatments to seeds may be given, such as soaking the
seeds in water for a day e.g. castor seeds and other slow-germinating seeds.
ii. Sometimes, seeds are soaked in sulphuric acid e.g. henbane seeds. Alternatively, testa is
partially removed by grindstone or by pounding seeds with coarse sand, e.g. Indian senna.
Several plant hormones like gibberellins, auxins are also used.
i. Seedlings are long-lived (in case of perennial drugs) and bear more heavily (in case of fruits).
ii. Seedlings are comparatively cheaper and easy to raise.
iii. Propagation from seed has been responsible for production of some chance-seedlings of highly
superior merits which may be of great importance to specific products, such as orange, papaya,
iv. In case of plants where other vegetative methods cannot be utilized, propagation from seeds is
the only method of choice.
i. Generally, seedling trees are not uniform in their growth and yielding capacity, as compared to
ii. They require more time to bear, as compared to grafted plants.
iii. The cost of harvesting, spraying of pesticides, etc. is more as compared to grafted trees.
iv. It is not possible to avail of modifying influence of root stocks on scion, as in case of
vegetatively propagated trees.
B- Asexual method: -
In case of asexual method of vegetative propagation, the vegetative part of a plant, such as stem or
root, is placed in such an environment that it develops into a new plant. Asexual method of vegetative
propagation consists of three types:
a- Natural methods of vegetative propagation.
b- Artificial methods of vegetative propagation.
c- Aseptic method of micropropagation (tissue-culture).
Natural methods of vegetative propagation: -
It is done by sowing various parts of the plants in well prepared soil. The following are the
examples of vegetative propagation: -
Plant part Example
Bulb Squill, garlic
Corm Colchicum, saffron
Tuber Jalap, aconite
Rhizome Ginger, turmeric
Sucker Mint, pineapple
Offset Aloe, valerian
Stolon Arrow root, liquorice
Artificial methods of vegetative propagations: -
The method by which plantlets or seedlings are produced from vegetative part of the plant by
using some technique or process is known as artificial method of vegetative propagation. These
methods are classified as under:
a- Cuttings: -
1. Stem cuttings
2. Soft wood cuttings: Berberry.
3. Semi hard wood cuttings: Citrus, camellia.
4. Hard wood cuttings: Orange, rose and bougainvillea.
5. Root cuttings: Brahmi.
6. Leaf cuttings: Bryophyllum.
7. Leaf bud cuttings.
b- Layering: -
1. Simple layering: Guava, lemon
2. Serpentine layering: jasmine, clematis
3. Air layering (Gootee): Ficus, mango, bougainvillea, cashew nut
4. Mount layering
5. Tip layering
c- Grafting: -
1. Whip grafting: Apple and rose
2. Tongue grafting
3. Side grafting: Sapota and cashew nut
4. Approach grafting: Guava and Sapota
5. Stone grafting: Mango
Aseptic methods of micropropagation (tissue culture): -
i. In micropropagation, the plants are developed in an artificial medium under aseptic conditions
from fine pieces of plants like single cells, callus, seeds, embryos, root tips, shoot tips, pollen
grains, etc. They are also provided with nutritional and hormonal requirements.
i. The plants are uniform in growth and yielding capacity. In case of fruit trees, uniformity in fruit
quality makes harvesting and marketing easy.
ii. Seedless varieties of fruits can only be propagated vegetatively e.g. grapes, pomegranates and
iii. Plants start bearing earlier as compared to seedling trees.
iv. Budding or grafting encourages disease-resistant varieties of plants.
v. Modifying influence of root-stocks on scion can be availed of.
vi. Inferior or unsuitable varieties can be over-looked.
i. In comparison to seedling trees, these are not vigorous in growth and are not long-
ii. No new varieties can be evolved by this method.
Factors influencing cultivation of medicinal plants: -
i. Altitude is a very important factor in cultivation of medicinal plants. The following are the examples
of medicinal and aromatic plants indicating the altitude for their successful cultivation:
Plant Altitude (Meters)
Tea 1000 – 1500
Cinchona 1000 – 2000
Camphor 1500 – 2000
Cinnamon 250 – 1000
Coffee 1000 – 2000
Clove Upto 900
Saffron Upto 1250
Cardamom 600 – 1600
i. Temperature is a crucial factor controlling the growth, metabolism and there by the yield of
secondary metabolites of plants. Many plants will grow better in temperate regions during summer,
but they lack in resistance to withstand frost in winter.
ii. The following are few examples of range conducive for luxuriant of certain medicinal plant:
Plant Optimum temperature (℉)
Cinchona 60 – 75
Coffee 55 – 70
Tea 70 – 90
Cardamom 50 – 100
i. Each and every plant species have its own soil and nutritive requirements. The three important basic
characteristics of soils are their physical, chemical and microbiological properties.
ii. Soil provides mechanical support, water and essential foods for the development of plants. Soil
consists of air, water, mineral matters and organic matters.
iii. Variations in particle size result in different soils ranging from clay, sand and gravel. Particle size
influences the water holding capacity of soil. The type and amount of minerals plays a vital role in
iv. Calcium favors the growth of certain plants whereas with some plants it does not produce any
effects. The plants are able to determine their own soil pH range for their growth; microbes should
be taken in to consideration which grows well in certain pH.
v. Depending upon the size of the mineral matter, the following names are given to the soil:
Types Particle size
Fine clay <0.002 mm
Coarse clay or salt 0.002 – 0.02
Fine sand 0.02 – 0.2
Coarse sand 0.2 – 2.0
vi. Depending upon percentage covered by clay, soils are following types:
Types of soil Percentage covered
Clay soil >50
Loamy soil 30 – 50
Slit loam soil 20 – 30
Sandy loam soil 10 – 20
Sandy soil >70
Calcareous soil >20% of lime
Soil fertility: -
i. It is the capacity of soil to provide nutrients in adequate amounts and in balanced proportion to
ii. If cropping is done without fortification of soil with plant nutrients, soil fertility gets lost. It is also
diminished through leaching and erosion.
iii. Soil fertility can be maintained by addition of animal manures, nitrogen-fixing bacteria or by
application of chemical fertilizers.
Fertilizers and Manures: -
Fertilizers are chemical substances supplied to the crop to increase their productivity. The fertilizers
contain the essential nutrients required by the plant, including nitrogen, potassium, phosphorus.
A- Chemical fertilizers: -
i. Plants are in need of sixteen nutrient elements for synthesizing various compounds. Some of
them are known as primary nutrients like nitrogen, phosphorus and potassium. Magnesium,
calcium and sulphur are required in small quantities and hence, they are known as secondary
ii. Trace elements like copper, manganese, iron, boron, molybdenum, zinc are also necessary for
plant growths are known as micronutrients.
iii. Carbon, hydrogen, oxygen and chlorine are provided from water and air. Every element has to
perform some specific function in growth and development of plants. Its deficiency is also
characterized by certain symptoms.
Elements of fertilizers: Functions, deficiency symptoms and forms
Function Deficiency symptoms
Forms in which
Builds up plant proteins
Improves the quality of leaf
appearance of the
plant, shunted growth,
less flowering, pre-
mature shedding of
are namely ammonium
nitrate sulphate (ANS),
nitrate (CAN) and
Being active part of the
nucleus of the plant cell, it
is essential for plants
Stimulant of seed and fruit
formation and also a
stimulant of root
Brings early maturity of
Shunted root growth.
Delays maturity and
retards the plant
growth in general.
are of two types: -
Mainly responsible for
resistance of plants against
diseases and adverse
Starch and sugar formation
are enhanced and their
movements in plant-parts
browning of tips of
Shriveled seed, fruits
Synthesis of various
proteins and oils, formation
of nodules and chlorophyll.
Leaves turn to
Essential constituent of
green plant pigment
Helps in carrying the
phosphorus and other plant
Essential for oil and fat
formation in plants.
Discoloration of leaves
and leaves tend to
Susceptible to fungal
Forms in which
Promotes root formation
and responsible for
hardness of plant tissue.
Detoxifying agents for
organic acids in plants (by
way of formation of calcium
oxalate and calcium
Translocation of carbon
hydrates necessary for
Drying of plants,
weaken the stem
structure, falling of
buds and blossoms
Root growth retarded
Hooking of the leaf
Formation of growth
hormone like Indole acetic
acid, essential part of most
of enzymes, helps in
utilization of phosphorus
and nitrogen in plants
Various symptoms in
different plants. In
general plants are
Yellow colored spots
develop on leaves
Zinc sulphate or Zinc
Activator for many plant
activities such as
and formation of vitamin A
Visible in certain
plants. Brown spots on
citrus fruits, yellowing
of younger leaves in
Involved in plant
catalyst for several
physiological reactions in
plants. Also, in synthesis of
leaves turn to yellow
Necessary for synthesis and
maintenance of chlorophyll,
as enzyme components
of young leaves,
yellowish green in
colour of leaves.
calcium ratio uptake and
utilization of calcium in
plants. Involved in lignin,
Terminal buds turn to
light green in colour,
death of growing
For nitrogen utilization and
Mottling of lower
necrosis, in-folding of
Stiffness of cell walls
Resists fungal infestations
Susceptible to fungal
B- Manures: -
i. Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of
animal feces, compost and green manure.
ii. Farm yard manure, castor seed cake, poultry manures, neem and karanj seed cakes vermin
compost, etc. are manures.
iii. Oil-cake and compost normally consists of 3–6% of nitrogen, 2% phosphates and 1–1.5% potash.
They are made easily available to plants. Bone meal, fish meal, biogas slurry, blood meal and
press mud are the other forms of organic fertilizers.
C- Biofertilizers: -
i. It is a substance which contains living micro – organism. These consist of different types of
microorganisms or lower organisms which fix the atmospheric nitrogen in soil and plant can use
them for their day to day use. Thus, they are symbiotic.
ii. Rhizobium, Azotobactor, Azosperillium, Bijericcia, Blue-green algae, Azolla, etc. are the
examples of biofertilizers.
Pests and Pests Control: -
Pests are undesired plant or animal species that causes a great damage to the plants. There are different
types of pests; they are microbes, insects, non-insect pests and weeds.
Fungi and viruses: -
Different types of fungi occur in medicinal plant cause diseases. Some examples are as follows –
Name of fungi Disease Characteristics
Ascochyta atropae Leaf necrosis Grayish – white irregular spot on leaf
Cercospora atropae Leaf spot
Round to angular brown spot with
chestnut colored margin
Phytophthora nicotianae Phytophthora root rot
Young leaf and branches are drops, whole
apical portion dries off
Dampening of young seedling, and wilt in
Pythium spinosum Pythium rhizome rot
Currularia prasadii Leaf bright
Collectotrichmm fuscum Anthracnose on digitalis
Many different viruses are responsible for some plant disease. They are mosaic causing necrosis of
leaves, petioles, and stem of different Solanaceous plants. Tobacco mosaic virus, cucumber mosaic
virus, and tobacco ring spot virus are observed on digitalis.
i. Ants of different varieties like Argentine ant: Linepithema humile, Gray ants: Formica aerata and
Formica perpilosa, Pavement ant: Tetramorium caespitum., Southern fire ant: Solenopsis xyloni,
Thief ant: Solenopsis molesta, spoil the soil by making nest and they feed honey dew secreted in
ii. Branch and Twig Borer (Melalgus confertus) burrow into the canes through the base of the bud or
into the crotch formed by the shoot and spur. Feeding is often deep enough to completely conceal
the adult in the hole. When shoots reach a length of 10–12 inches, a strong wind can cause the
infected parts to twist and break.
iii. Cutworms (Peridroma saucia) injures the buds and so the buds may not develop. Leaf hoppers
(Erythroneura elegantuhi) remove the contents of leaf cells, leaving behind empty cells that
appear as pale-yellow spots.
iv. Oak twig pruners are known as shoot, twig and root insects that affects the above-mentioned.
Tilling the soil will also affects the nesting sites of ants and help to reduce their populations, collection
and destruction of eggs, larvae, pupae and adults of insects, trapping the insects, insecticides, creating
a situation to compete among males for mating with females, cutworms can be prevented by natural
enemies like, predaceous or parasitic insects, mammals, parasitic nematodes, pathogens, birds, and
i. Weeds reduce growth and yields of plants by competing for water, nutrients, and sunlight. Weed
control enhances the establishment of new plants and improves the growth and yield of established
ii. Soil texture and organic matter influence the weed species that are present, the number and timing
of cultivations required, and the activity of herbicides.
iii. Annual species, such as puncturevine, crabgrass, horseweed, and perennials like johnsongrass,
nutsedge, and bermudagrass are more prevalent on light-textured soil while perennials such as
curly dock, field bindweed, and dallis grass are more common on heavier-textured soils.
iv. Few common weeds are, Bermuda grass, It is a vigorous spring- and summer-growing perennial,
Dallis grass, it is a common perennial weed that can be highly competitive in newly planted plants.
v. The other weeds are pigweeds Amaranthus spp., pineapple-weed Chamomilla suaveolens,
nightshades Solanum spp., etc.
Use of low rates of herbicides:
Herbicides are traditionally discussed as two groups: those that are active against germinating weed
seeds (pre-emergent herbicides) and those that are active on growing plants (post-emergent
herbicides). Some herbicides have both pre-and post-emergent activity.
Preemergent herbicides are active in the soil against germinating weed seedlings. These herbicides are
applied to bare soil and are leached into the soil with rain or irrigation where they affect germinating
Post emergent herbicides are applied to control weeds already growing in the vineyard. They can be
combined with preemergent herbicides or applied as spot treatments during the growing season.
Plant growth regulators and their regulation: -
1. Plant hormones (phytohormones) are physiological intercellular messengers that control the complete
plant lifecycle, including germination, rooting, growth, flowering, fruit ripening, foliage and death.
2. The term ‘plant growth factor’ is usually employed for plant hormones or substances of similar effect
that are administered to plants. Five major classes of plant hormones are mentioned: auxins,
cytokinins, gibberellins, abscisic acid and ethylene.
1. The term auxin is derived from the Greek word auxein which means to grow. Generally, compounds
are considered as auxins if they are able to induce cell elongation in stems and otherwise resemble
indoleacetic acid (the first auxin isolated) in physiological activity.
2. Auxins were the first plant hormones discovered. Charles Darwin described the effects of light on
movement of canary grass coleoptiles. The coleoptile is a specialized leaf originating from the first
3. When unidirectional light shines on the coleoptile, it bends in the direction of the light. If the tip of
the coleoptile was covered with aluminum foil, bending would not occur towards the unidirectional
4. Darwin’s experiment suggested that the tip of the coleoptile was the tissue responsible for perceiving
the light and producing some signal which was transported to the lower part of the coleoptile where
the physiological response of bending occurred. It is confirmed, when he cut off the tip of the
coleoptile and exposed the rest of the coleoptile to unidirectional light curvature did not occur.
5. Salkowski discovered indole-3-acetic acid (IAA) in fermentation media. IAA is the major auxin
involved in many of the physiological processes in plants.
6. Indole acetic acid (IAA) is the principle natural auxin and other natural auxins are indole-3-
acetonitrile (IAN), phenyl acetic acid and 4-chloroindole-3-acetic acid.
7. The exogenous or synthetic auxins are indole-3-butyric acid (IBA), α – naphthyl acetic acid (NAA),
2-napthyloxyacetic acid (NOA), 1 – naphthyl acetamide (NAD), 5-carboxymethyl- N, N-dimethyl
dithiocarbamate, 2,4-dichlorophenoxy acetic acid (2,4-D), etc.
8. Structure of auxins: -
Function of auxins: -
1. Stimulates cell elongation.
2. The auxin supply from the apical bud suppresses growth of lateral buds. Apical dominance is the
inhibiting influence of the shoot apex on the growth of axillary buds. Removal of the apical bud
results in growth of the axillary buds.
Replacing the apical bud with a lanolin paste containing IAA restores the apical dominance. Auxin
(IAA) causes lateral buds to make ethylene, which inhibits growth of the lateral buds.
3. Differentiation of vascular tissue (xylem and phloem) is stimulated by IAA.
4. Auxin stimulates root initiation on stem cuttings and lateral root development in tissue culture
5. Auxin mediates the tropistic response of bending in response to gravity and light.
6. Auxin has various effects on leaf and fruit abscission, fruit set, development, and ripening, and
flowering, depending on the circumstances.
1. Cytokinins are compounds with a structure resembling adenine. Kinetin was the first cytokinin
identified and so named because of the compounds ability to promote cytokinesis (cell division).
Though it is a natural compound, it is not made in plants, and is therefore usually considered a
2. The common naturally occurring cytokinin in plants today is called zeatin which was isolated from
3. There are more than 200 natural and synthetic cytokinins identified. Cytokinin concentrations are
more in meristematic regions and areas of continuous growth potential such as roots, young leaves,
developing fruits, and seeds.
4. The first cytokinin was isolated from herring sperm. This compound was named kinetin because of
its ability to promote cytokinesis (cell division). The first naturally occurring cytokinin was isolated
from corn called zeatin.
5. The naturally occurring cytokinins are zeatin, N6 dimethyl amino purine, isopentanyl aminopurine.
The synthetic cytokinins are kinetin, adenine, 6-benzyl adenine benzimidazole and N, N’-diphenyl
6. Structure of cytokinins: -
Function of cytokinins: -
1. Stimulate cell division (cytokinesis).
2. Stimulate morphogenesis (shoot initiation/bud formation) in tissue culture.
3. Stimulate the growth of lateral (or adventitious) buds release of apical dominance.
4. Stimulate leaf expansion resulting from cell enlargement.
5. May enhance stomatal opening in some species.
6. Promotes the conversion of etioplasts into chloroplasts via stimulation of chlorophyll synthesis.
7. Stimulate the dark-germination of light-dependent seeds.
8. Delays senescence. Promotes some stages of root development.
1. All gibberellins are derived from the ent-gibberellane skeleton. Gibberellins are classified on the
basis of structure as well as function. The gibberellins are named GA1…, GAn in order of discovery.
2. Gibberellic acid was the first gibberellin to be structurally characterized as GA3. There are currently
136 GAs identified from plants, fungi and bacteria.
3. They are a group of diterpenoid acids that functions as plant growth regulators influencing a range of
developmental processes in higher plants including stem elongation, germination, dormancy,
flowering, sex expression, enzyme induction and leaf and fruit senescence.
4. The origin of research into gibberellins can be traced to Japanese plant pathologists who were
investigating the causes of the ‘bakanae’ (foolish seedling) disease which seriously lowered the yield
of rice crops in Japan. Symptoms of the disease are pale yellow, elongated seedlings with slender
leaves and stunted roots. Severely diseased plants die whereas plants with slight symptoms survive
but produce poorly developed grain, or none at all.
5. In 1898 Shotaro Hori demonstrated that the symptoms were induced by infection with a fungus
belonging to the genus Fusarium, probably Fusarium heterosporium Necs.
6. In 1912, Sawada suggested that the elongation in rice seedlings infected with bakanae fungus might
be due to a stimulus derived from fungal hyphae.
7. In the 1930s, the imperfect stage of the fungus was named Fusarium moniliforme (Sheldon) and the
perfect stage, was named as Gibberella fujikuroi.
8. In 1934, Yabuta isolated a crystalline compound from the fungal culture filtrate that inhibited growth
of rice seedlings at all concentrations tested. The structure of the inhibitor was found to be 5-n-
butylpicolinic acid or fusaric acid. The formation of fusaric acid in culture filtrates was suppressed by
changing the composition of the culture medium. As a result, a non-crystalline solid was obtained
from the culture filtrate that stimulated the growth of rice seedlings. This compound was named
gibberellin by Yabuta.
9. In 1955, members of Sumuki group, succeeded in separating the methyl ester of gibberellin A into
three components, from which corresponding free acids were obtained and named gibberellins Al,
A2, and A3. Gibberellin A3 was found to be identical to gibberellic acid.
10. Structure of gibberellins:
Function of gibberellins: -
1. Stimulates stem elongation by stimulating cell division and elongation. GA controls internode
elongation in the mature regions of plants. Dwarf plants do not make enough active forms of GA.
2. Flowering in biennial plants is controlled by GA.
3. Breaks seed dormancy in some plants that require stratification or light to induce germination.
4. Stimulates α-amylase production in germinating cereal grains for mobilization of seed reserves.
5. Juvenility refers to the different stages that plants may exist in. GA may help determine whether a
particular plant part is juvenile or adult.
6. Stimulates germination of pollen and growth of pollen tubes.
7. Induces maleness in dioecious flowers (sex expression).
1. It is a simple organic molecule present in the form of volatile gas. It is present in ripening fruits,
flowers, stems, roots, tubers, and seeds.
2. It is produced by incomplete burning of carbon rich substances like natural gas, coal, and petroleum.
3. Ethylene is produced in all higher plants and is produced from methionine in essentially all tissues.
Functions of ethylene: -
1. Production stimulated during ripening, flooding, stress, senescence, mechanical damage, infection.
2. Regulator of cell death programs in plants (apoptosis).
3. Stimulates the release of dormancy.
4. Stimulates shoot and root growth and differentiation (triple response).
5. Regulates ripening of climacteric fruits.
6. May have a role in adventitious root formation.
7. Stimulates leaf and fruit abscission.
8. Flowering in most plants is inhibited by ethylene.
9. Mangos, pineapples and some ornamentals are stimulated by ethylene.
Abscisic Acid: -
1. ABA is a naturally occurring sesquiterpenoid (15-carbon) compound in plants, which is partially
produced via the mevalonic pathway in chloroplasts and other plastids.
2. Because it is synthesized partially in the chloroplasts, it makes sense that biosynthesis primarily
occurs in the leaves. The production of ABA is by stresses such as water loss and freezing
3. Two compounds were isolated and named as abscisin I and abscisin II. Abscisin II is presently called
abscisic acid (ABA).
Functions of abscisic acid: -
1. The abscisic acid stimulates the closure of stomata.
2. Involved in abscission of buds, leaves, petals, flowers, and as well as in dehiscence of fruits.
3. Production is increased by stresses such as water loss and freezing temperatures.
4. Involved in bud dormancy.
5. Prolongs seed dormancy and delays germination (vivipary).
6. Inhibits elongation.
7. ABA coming from the plastids promotes the metabolism of ripening.
8. Promotes senescence.
9. Can reverse the effects of growth stimulating hormones.
Collection, processing for quality assurance, storage and preservation of herbal
i. Collection is the most important step which comes after cultivation.
ii. Drugs should be collected when they contain maximum amount of constituents in a highly scientific
manner. The season at which each drug is collected is so important, as the amount, and the nature of
the active constituents could be changed throughout the year. For example, Rhubarb is collected
only in summer seasons because no anthraquinone derivatives would be present in winter season but
anthranols are converted to anthraquinones during summer.
iii. Not only the season but also the age of the plant should be taken in to great consideration since it
governs not only the total amount of active constituents produced in the plants but also the
proportions of the constituents of the active mixture. High proportion of pulegone in young plants of
peppermint will be replaced by menthone and menthol and reduction in the percentage of alkaloids
in datura as the plant ages are examples of the effect of aging in plants.
iv. Generally, the leaves are collected just before the flowering season, e.g. vasaka, digitalis, etc., at this
time it is assumed that the whole plant has come to a healthy state and contain an optimum amount
v. Flowers are collected before they expand fully, e.g. clove, saffron, etc. Some fruits are collected after
their full maturity while the others are collected after the fruits are ripe.
vi. Barks are usually collected in spring season, as they are easy to separate from the wood during this
season. The barks are collected using three techniques, felling (bark is peeled off after cutting the
tree at base), uprooting (the underground roots are dug out and barks are collected from branches
and roots) and coppicing (plant is cut one meter above the ground level and barks are removed).
vii. Underground parts should be collected and shaken, dusted in order to remove the adhered soil;
water washing could be done if the adhered particles are too sticky with plant parts.
viii. The unorganized drugs should be collected from plants as soon as they ooze out, e.g. resins, latex,
Harvesting of crude drugs: -
i. Harvesting is an important operation in cultivation technology, as it reflects upon economic aspects
of the crude drugs. An important point which needs attention over here is the type of drug to be
harvested and the pharmacopoeial standards which it needs to achieve.
ii. Harvesting can be done efficiently in every respect by the skilled workers. Selectivity is of advantage
in that the drugs other than genuine, but similar in appearance can be rejected at the site of
iii. In certain cases, it cannot be replaced by any mechanical means, e.g. digitalis, tea, vinca and senna
leaves. The underground drugs like roots, rhizomes, tubers, etc. are harvested by mechanical
devices, such as diggers or lifters. The tubers or roots are thoroughly washed in water to get rid of
iv. Drugs which constitute all aerial parts are harvested by binders. Flowers, seeds and small fruits are
harvested by a special device known as seed stripper.
v. The technique of beating plant with bamboos is used in case of cloves. The cochineal insects are
collected from branches of cacti by brushing. The seaweeds producing agar are harvested by long
vi. Peppermint and spearmint are harvested by normal method with mowers, whereas fennel, coriander
and caraway plants are uprooted and dried. After drying, either they are thrashed or beaten and the
fruits are separated by winnowing.
Drying of crude drugs: -
i. Before marketing a crude drug, it is necessary to process it properly, so as to preserve it for a longer
time and also to acquire better pharmaceutical elegance.
ii. This processing includes several operations or treatments, depending upon the source of the crude
drug (animal or plant) and its chemical nature.
iii. Drying consists of removal of sufficient moisture content of crude drug, so as to improve its quality
and make it resistant to the growth of microorganisms. Drying inhibits partially enzymatic reactions.
iv. Drying also facilitates pulverizing or grinding of a crude drug. In certain drugs, some special methods
are required to be followed to attain specific standards, e.g. fermentation in case of Cinnamomum
zeylanicum bark and gentian roots.
v. Drying can be of two types - (1) natural (sun drying) and (2) artificial.
A- Natural Drying (Sun-Drying): -
i. In case of natural drying, it may be either direct sun-drying or in the shed. If the natural
colour of the drug (digitalis, clove, senna) and the volatile principles of the drug
(peppermint) are to be retained, drying in shed is preferred.
ii. If the contents of the drugs are quite stable to the temperature and sunlight, the drugs can be
dried directly in sunshine (gum acacia, seeds and fruits).
B- Artificial Drying: -
Drying by artificial means includes drying the drugs in:
a- An oven; i.e. Tray-dryers: -
i. The drugs which do not contain volatile oils and are quite stable to heat or which need
deactivation of enzymes are dried in tray dryers.
ii. In this process, hot air of the desired temperature is circulated through the dryers and
this facilitates the removal of water content of the drugs
iii. Example: belladonna roots, cinchona bark, tea and raspberry leaves and gums are dried
by this method.
b- Vacuum dryers: -
i. The drugs which are sensitive to higher temperature are dried by this process, e.g.
Tannic acid and digitalis leaves.
c- Spray dryers: -
i. Few drugs which are highly sensitive to atmospheric conditions and also to temperature
of vacuum-drying are dried by spray-drying method.
ii. The technique is followed for quick drying of economically important plant or animal
constituents, rather than the crude drugs.
iii. Examples of spray drying are papaya latex, pectin, tannins, etc.
Garbling (dressing): -
i. The next step in preparation of crude drug for market after drying is garbling. This process is desired
when sand, dirt and foreign organic parts of the same plant, not constituting drug are required to be
ii. This foreign organic matter (extraneous matter) is removed by several ways and means available and
practicable at the site of the preparation of the drugs.
iii. Excessive stems in case of lobelia and stramonium need to be removed, while the stalks, in case of
cloves are to be deleted.
iv. Drugs constituting rhizomes need to be separated carefully from roots and rootlets and also stem
v. Pieces of iron must be removed with the magnet in case of castor seeds before crushing and by
shifting in case of vinca and senna leaves.
vi. Pieces of bark should be removed by peeling as in gum acacia.
Packing of crude drugs: -
i. The morphological and chemical nature of drug, its ultimate use and effects of climatic conditions
during transportation and storage should be taken into consideration while packing the drugs.
ii. Aloe is packed in goat skin. Colophony and balsam of tolu are packed in kerosene tins, while
asafoetida is stored in well closed containers to prevent loss of volatile oil.
iii. Cod liver oil, being sensitive to sunlight, should be stored in such containers, which will not have
effect of sunlight, whereas, the leaf drugs like senna, vinca and others are pressed and baled.
iv. The drugs which are very sensitive to moisture and also costly at the same time need special
attention, e.g. digitalis, ergot and squill. Squill becomes flexible; ergot becomes susceptible to the
microbial growth, while digitalis loses its potency due to decomposition of glycosides, if brought in
contact with excess of moisture during storage. Hence, the chemicals which absorb excessive
moisture (desiccating agents) from the drug are incorporated in the containers.
v. Colophony needs to be packed in big masses to control autooxidation. The crude drugs like roots,
seeds and others do not need special attention and are packed in gunny bags, while in some cases
bags are coated with polythene internally.
Storage of crude drugs: -
Crude drugs are normally stored in glass containers or in gunny bags on commercial scale
Following measures will preserve the crude drugs suitably: -
1. Floor area of store room should be tidy, dry, hygienic, without any cracks and easy to clean.
2. Air conditioning facility with dehumidifier is desired for the store room.
3. Crude drugs should be stored on shelves with sufficient distance from walls to permit free movement
of trollies used for transport.
4. Protection against rodents, insects and line-stocks should be provided.
5. Arrangements to prevent pest-infestations mould formation should also be provided.
6. Well filled, well closed, air-tight containers are desired for storage of crude-drugs and should be kept
away from direct sunlight and in cool place.
7. Arrangements to inspect the store room (premises) at regular intervals be made.
8. Packaging materials used to store should be non-polluting and should not absorb moisture.
9. Wooden boxes, paper bags, newspapers should not be used for storage of crude drugs.
10. As a safety measure, fire-extinguishers should be available in store room.
11. Aluminum containers should not be used to store volatile oils.
12. Fiber glass or glass lined containers are most suitable for storage.
i. Mutation is represented as variation in characters of the species. It is caused either due to
environmental changes or changes in hereditary constitution.
ii. Normally, as a response to environmental changes, the variations are observed, but the original traits
are restored when changes in environment are also withdrawn or disappeared.
iii. This type of change and restoring is no heritable and also not built into genotype. They are termed
only as phenotypic variations and commonly called as modifications.
iv. However, when a change occurs in the genome of an individual which is no caused due to
environment, it may make a permanent evolutionary change. This is termed as mutation and
represents a sudden change in genotype causing qualitative or quantitative alterations of genetic
v. Mutations are of two types namely chromosomal mutations and point mutations. The former type of
mutation is also called chromosomal aberration, which in many cases leads to changes in amount or
position of genetic material. On the other hand, the changes with a gene or cistron of DNA molecule
cause point mutations and it is permanent and heritable.
vi. Mutation which occurs due to some unknown reason from nature is called as spontaneous mutation.
This has been observed in some plants, bacteria, viruses, etc.
vii. Mutations can also be induced by artificial means with certain reagents called mutagens and are called
viii. The various mutagens used are exposure to UV rays, X-rays, ionizing radiations, certain chemicals
abnormal environment etc. The chemical mutagens used are nitrogen mustard, formaldehyde nitrous
acid, ethyl ethane.
ix. The changes caused due to mutations include morphological and anatomical changes, as well as,
changes in the chemical composition of the plants. This is significant for the medicinal plants.
x. The artificial mutations are those which are induced artificially in the living organism by exposing
them to abnormal environment, such as radiations, certain physical conditions like temperature and
chemicals, all of which are called mutagens or mutagenic agents.
a- Radiation mutations:
The electromagnetic waves of short wavelength (ultra violet light, x-rays, gamma-rays, alpha
and beta rays) are radiation mutagens.
The X-rays and gamma rays are called ionizing radiations, and also include alpha particles,
beta rays, thermal and fast neutrons.
Due to ionizing radiations, in many cases, water molecule in a biological system releases one
electron and becomes unstable and eventually splits into hydrogen ion and hydroxyl radical.
Hydrogen ion reacts with O2 and produces hydroperoxyl (HO) radical. Both these radicals viz
hydroperoxyl and hydroxyl are potent oxidizing agents. When chromosomes and their DNA ate
struck by such radicals, they react due to which sugar-phosphate part of DNA may be impaired
leading to chromosomal mutations, like breaks, deletions, additions, inversions and
b- Chemical mutations:
Some chemical mutagens, like nitrogen mustard, formaldehydes nitrous acid and ethyl ethane
sulphonate alter chemical constitution of DNA bases and cause transitional substitution in
But some compounds like 2-aminopurine, urethane, 5-bromouracil, caffeine, triazine, phenol
and certain other carcinogens act as a base analogue and bring out copy error mutations in
In general, the chemical mutagens have profound cellular effects like production of abnormal
DNA (nitrogen mustard), inhibition of deoxyribonucleotide synthesis (deoxyadenosine), and
inhibition of cytochrome oxidase with resultant peroxide formation (inorganic cyanides).
i. Polyploidy is the condition in which a normally diploid cell or organism aquirs one or more additional
sets of chromosomes.
ii. Polyploidy has exhibited various useful effects on medicinal plants like digitalis, mentha species
poppy, plants containing tropane alkaloids, lobelia, etc.
iii. The specific number of chromosomes is a character of each species and is called genome which is
observed in all types of organisms.
iv. The term euploidy is a type of ploidy in which genome contains whole set of chromosomes and
euploidy includes monoploidy, diploidy and polyploidy.
v. When the organism contains more than two genomes, it is called polyploidy. The polyploidy occurs in
a multiple series of 3, 4, 5, 6, 7, 8 etc. of the basic chromosome or genome number and then
accordingly, it is called triploidy, tetraploidy, pentaploidy, hexaploidy, heptaploidy and octaploidy
vi. Polyploidy is caused through cell generation, physical agents like X-rays, centrifugation. temperature
chocks and chemical agents, mainly colchicine, veratrin, sulphanilamide, hexachloro cyclohexane, and
vii. The chemical agents cause disturbance to mitotic spindle of dividing diploid cell and cause non-
segregation of already duplicated chromosome and thus convert diploids into tetraploid cells.
viii. The phenomenon of polyploidy is of greater significance to medicinal plants. It may cause formation of
new species, adaptability to various habitats and mainly accumulation of vitamins.
ix. Perhaps, the best-known chemical to cause polyploidy is colchicine, an alkaloid obtained from
Colchicum species like Colchicum autumnale, C. luteum. Colchicine prevents sister chromatids from
separating into daughter nuclei at anaphase. The colchicine activity is caused due to its interaction
with disulphide bonds of spindle protein and by inhibition of conversion of globular proteins to fibrous
i. The process through which hybrids are produced is called hybridization. A hybrid is an organism
which results from crossing of two species or varieties differing at least in one set of characters.
ii. The resultant hybrids are monohybrids (one pair of different characters), dihybrids (two pairs of
different characters) or polyhybrid (more than two pairs of different characters).
iii. Hybridization helps in inducing in a single variety, the favourable characters of other varieties or
species, and sometimes producing new and favourable characters which are not present in both the
iv. The hybridization of Withania somnifera (Israeli chemotype II) and W. somnifera (South African
chemotype) has led to formation of a new hybrid which contains three new withanolide.
v. The hybrids like Digitalis purpurea with D. lanata and D. purpurea with D. lutea contain principal
glycoside as lanatosides A, along with lanatosides B and E, but devoid of lanatoside C or purpurea
vi. During the cross of Solanum incanum (1.8 per cent solasodine) and S. melongena (traces of
solasodine), first generation bears more fruits (berries) with solasodine up to 0.5 per cent. Second
generation has proved to be a high yielding source for solasodine.