Factor affecting Cultivation of crude drugs

  AS per PCI Syllabus

(S. Y.  B. Pharm Sem IV) Unit -II

 

 

Cultivation of crude drugs:

Cultivation of medicinal plants requires intensive care and management.

The conditions and duration of cultivation required vary depending on the quality of medicinal plant materials required.

 

Factors affecting cultivation

1. Altitude

2. Temperature

3. Rainfall

4. Soil

5. Soil fertility

6. Fertilizers

7. Pest and pest controlled

 

1. Altitude –

Altitude is an important factor which affects the cultivation of medicinal plants.

With an increase in altitude above sea level there are changes in values of temperature, humidity, solar radiation etc. Due to these changes vegetation at different altitudes differ much.



2. Temperature  

Temperature profoundly affects the plant growth and metabolism. It also affects the rate of transpiration and regulates the activity of enzymes which in turn regulates the physiological processes. 

Extremes of temperature both on cold and hot sides affects the quality of
medicinal plants. Although each species has become adapted to its own natural
environment, plants are frequently able to exist in considerable range of temp.

 



3. Rainfall

Different regions of earth receive different quantities of rainfall depending upon geographical features. The quantity, duration & intensity of rainfall regulates the plant life.


The effects of rainfall on vegetation must be considered in relation to the annual rainfall, its distribution throughout the year & its effects related to the water holding capacity of the soil. 

Majority of the plants need sufficient amount of rainfall for the growth. 

 

Excessive or less rainfall affects the plant life and constituents of the plant. For example in Cassia angustifolia it has been proved that short term drought increases the concentration of sennosides A and B but in longer term it causes loss of biomass.

 

Day- length and radiation characteristics –

Light plays an important role in photosynthesis. Light also regulates CO2 and oxygen exchange between plants and atmosphere.

Plants vary in both the amount and intensity of light which they require. Light in some plants determines the content of constituents.

 

For example in cinchona and belladonna a full sunshine gives a higher content of alkaloids as compared to shade. 

 

4. Soil –

Soil is the medium in which root grows, anchor the plants and from which the derive water and nutrients. All the soils have the following components;

The mineral matter the soil organism and the organic matter soil water and soil solution the soil atmosphere. 

 

The mineral particles such as sand, silt or clay are the primary material that constitute the soil.

Depending upon the size of mineral matter the International Society of soil. science has given different names to these mineral particles which are as follows  

 



Clay is formed as the final product of weathering and through precipitation of aluminum and silicon salts present in dissolved state in the soil moisture.



It provides adhesive and cohesive properties to the soil. The relative percentage of coarse sand, fine sand, silt and clay determines soil texture. 

On the basis of the proportion of different sized particles soils are classified into different textural groups as follows –

 



The organic matter in soil is received from the dead bodies of plants and animals of all types and sizes. Organic matter is the chief source of mineral's return to soil.

 

The quantity and availability of soil water to the plants is a great determining factor of the nature and composition of vegetation of any place. Rain is the principle source of water for the soil. An ideal soil required for the plant growth should have half of the pores filled with water and rest with air as good aeration stimulates the root development.

 

The pH values of soil shows much correlations with the soil type, vegetation type thus affecting plants growth, lime requirement and mineral nutrition. The pH of the soil strongly affects the microbial activities. The maximum nutrients are available to the plants in between the pH range of 6.5 to 7.5.

 

5. Soil fertility is defined as the capacity of the soil to provide nutrition to the plants in balanced and adequate amount.

 

6. Fertilizers- Plants need 16 nutrient elements for their growth and metabolism. Depending upon the quantity needed the nutrients are classified into macronutrients and micronutrients. 

Macronutrients are needed in large quantities and micronutrients in trace. Carbon, hydrogen, nitrogen, oxygen, calcium, potassium, phosphorous, sulphur and  magnesium are the macronutrients and copper, zinc, boron,molybdenum, iron, manganese, chlorine are the micronutrients (Trace elements).Carbon, hydrogen and oxygen are obtained, from air and water.

These elements are supplied to the plants through the soil. These elements can also supplied to the plants through animal manures and chemical fertilizers because soil is unable to cater the needs of plants. 

Each element has its own role in growth and development of plants and their deficiency may cause disease.

 

7. Pests and pest control – Pest is an undesired animal or plant species. The various types of pest which infests the plants are like virus, fungi, weeds, insects and non insect pests.

These pests directly affects the plant growth and development and produce disease which ultimately influences the quality and yield of crude drugs.

Hence, control of pest is essential and it should be given importance.

Types of Pests – The various types of pests which infests the plants are like virus, fungi, weeds, insects and non insect pests.

 

Virus 

Various types of virus causes disease in medicinal plants. Strains of Cucumber mosaic virus causes disease in hyoscyamus whereas Tobacco mosaic virus, Tobacco ring spot virus and Cucumber mosaic virus are known to cause infection in digitalis.

Potato virus -X causes mosaic disease in potato in which inter-veinal mottling of leaves is common and it is followed by necrosis. 

The affected leaves droop and wither. Banana virus- I causes bunchy top in banana which results in marginal chlorosis and curling of leaves and ultimately plant remains stunted.

 

Fungi –

The various types of fungi are known to cause disease in medicinal plants. Cerscospora  dioscorea produces leaf-spot on dioscorea and Alternaria tennussima produces leaf spot on datura.

Uromyces hobosonii produces rust. Uromyces ciceris-arietini and Uromyces fabae produces rust on gram and pea respectively. 

Cerscospora personata and Cerscospora  arachidicola causes tikka disease in groundnut. Similarly several other pathogenic fungi infest the medicinal plants and causes disease.

 

Weeds –

A weed is an undesired plant growing in crop field. Weeds causes drastic damages to the plants and this problem is common in agriculture. Majorly it causes loss of nutrients and water in all the plants. It also causes loss of space, increases the attacks of Fungi, bacteria, virus and insects which causes disease and ultimately it influences the quality and price of crude drugs.

There are few weeds which causes allergies like medican tea and ragweed causes hay fever. Varnish tree and western poison oak causes dermatitis. Therefore weeds should be controlled properly.

 

Insects –

 Different types of insect pests are reported which attacks on plants and causes severe problems. The plants should be protected from them. The various examples of insects pest are like Ephestia elutella (Moth)" attacks on tobacco, rose petals and cocoa.

 Tinea pellionella and Ephestia kuechniella (Moths) attacks on almond, tobacco and capsicum.

The other types of insect pests which causes damage to medicinal plants are like aphids, caterpillar, termites, grass-hoppers, spiders, mites and locusts.

 

Non - insect pests –

Non insect pests are classified into two groups viz. vertebrates and invertebrates. Vertebrates includes rabbits, monkey, rat, squirrel, pigs, hares and deer etc.

Invertebrates are like snails, crabs, mites and nematodes etc. The rodents have sharp and gnawing incisor with which they causes severe damage to stored crude drugs. The fecal material of these animals causes contamination of crude drugs.

 

Methods of pest control -

1. Agricultural method – It involves various types of methods. One of the method is that in which fields are deeply ploughed which removes the weeds and insects. Crop rotation can also be followed. In this method crops are grown alternatively.

Another method which is common now a days is crop improvement. It is achieved by a technique called as plant breeding. By this technique hybrid varieties of the plants are produced which are resistant to disease and pest.

 

2. Biological method – Biological control brings about reduction in activity of pest mostly insect, by another organism. This may be biocidal or biostatic. In biocidal biological control one organism kills the other while in biostatic the organism only inhibits the other.

 

Biological control is defined by Garrett as "any condition under which or practice. whereby survival or activity of a pathogen is reduced through the agency of any other living organism (except man) with the result that there is a reduction in the incidence of the disease caused by pathogen".

 

Mechanism of Biological control –

1. Antibiosis- where one species secretes some chemicals which inhibits the growth of the other.

2. Exploitation - where one is parasitic or predatory on other.

3. Competition - the organism competes for a substances which is in short supply. The real value of the biological control does not lie in natural methods but in abstracting their underlying mechanism and applying them.

3. Chemical control- Pests can be controlled by using pesticides. Pesticides are the chemicals derived from natural or chemical sources effective against pest in small concentrations Pesticides posses toxic effects so their, use is governed by Insecticide Act in India.

Pesticide are classified according to the type of organism against which they are effective viz fungicides, nematocides, molluscicides, rodenticides, bactericide etc.

 

Fungicides-

These are the agents that destroy fungi Examples are Chlorophenols, Bordeaux mixture, Azoxystrobin, Benomyl, Benzalkonium chloride, Allyl alcohol etc.

 

Insecticides-

Agents which kill the insects are termed as insecticides. Examples are Parathion, Malathion, "D.D.T, D.D.E, Sodium arsenate, Benzene hexachloride (BHC), Hep-tachlor, Phorate, Demeton, Carbaryl, Dieldrin, Aldrin, Methoxychlor etc.

 

Herbicides-  

The weed killers are termed as herbicides. Examples are Sulphuric acid, Calcium arsenate, 2,4-dichlorophenoxy acetic acid etc.

 

Rodenticides-

These agents are destructive to rodents. Examples are Strychnine, Red squill, Wärfarin, Bromodiolone, Brodifacoum, Zinc phosphide, Yellow phosphorous etc.

 

4. Mechanical control- This method involves the destruction of pests by manual labour using different devices. The techniques used are hand-picking, pruning, burning and trapping of pests.

Flying insects can be trapped by placing flavoured attractants (flavoured with anise oil, rose oil etc.) mixed with saw-dust in funnel shaped container.

These containers are designed in such a way that entry into these containers is easy but it is very difficult to come out. Rodents like rats, rabbits etc. can be trapped by using rat traps.


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