UNIT 1
Structure
1.1Introduction
1.2Objectives
1.3Plant biodiversity
1.3.1Plant biodiversity : concept
1.3.2Types of biodiversity
1.3.3Biodiversity at global levels
1.3.4Status in India
1.3.5Utilization of plant biodiversity
1.4Sustainable development
1.4.1Basic concept
1.4.2The elements of sustainable development
1.4.3Different ways of viewing sustainable development
1.4.4Importance of sustainable development
1.4.5The need for sustainable development
1.4.6What we can do?
1.5Origins of agriculture
1.5.1Ancient origin
1.5.2Middle ages
1.5.3Modern era
1.5.4Ancient Indian economic botany
1.6World centres of primary diversity of domesticated plants
1.6.1Origin of crop plants
1.6.2Plants domestication
1.6.3World centres of origin of domesticated plants
1.6.4Process of domestication of crop plants from their wild progenitors
1.7Let us sum up
1.8Check your progress : the key
1.9Assignments/ Activities
1.10References/ Further Readings
1.1INTRODUCTION
A Upanishadic rhymes is
“A Guru (i.e., master) asked his disciple to bring some waste plants, thereupon the disciple goes in search of these plants and later comes only to report to his guru that he could not find a single plant which is 'waste'.”
This means that plant on earth has some value.Nature has given plenty of plant resources to human beings and he started tailoring them ever since the beginnings of civilization in manifold ways to suit his needs whether knowingly or unknowingly. The civilization of man went hand in hand with the domestication and cultivation of crop plants and their evolution took place according to the evolution of mind and thought. Millions of years, the evolution of crop plants has been taking place with the direct human agency either consciously or unconsciously.
The quest for more knowledge of plant resources continues concomitant with the rise in population and depletion of food materials. Many new plants have been added to the existing ones with the modern techniques and trends in human utilization.
Plants bring about economy to the country at large and it is a fact that the wealth of any country largely depends upon its agriculture and plant products.
In this unit, we shall review all aspect of plant diversity, sustainable development, and origin of plants and their domestication.
1.2OBJECTIVES
The main objectives of this unit are to know the plant wealth present on the earth, sustainable use of its components and their conservation. The major objectives of present study are :
To understand the plant biodiversity and its component;
To study the sustainable development and identify the sustainable use of natural resources;
To understand origin of agriculture and primary centres of domesticated plants;
To explain the process of domestication of crop plants.
1.3PLANT BIODIVERSITY
1.3.1Concept and definition
Planet Earth is endowed with a rich variety of life forms and the teeming millions of these living organisms have been well-knit by the laws of nature. The inter-dependence of the various life forms starting from the unicellular primary producers to the complexly built higher plants and animals is a unique feature of this green planet.
Bio-diversity, as this assemblage of life forms is referred to, has now been acknowledged as the foundation for sustainable livelihood, and food security. Scientists have estimated that more than 50 million species of plants and animals including invertebrates and micro-organisms occur on earth and hardly 2 million of them have been described by man so far. Scientists are also aware of the immense potentials of the various life forms especially in the context of recent advances made in science and technology. The incessant human assault on forests has left indelible scars on nature. One result of the United Nations Conference on Environment and Development held in Rio de Janerio in June 1992 was a “Convention on Biological Diversity” which was signed by 156 countries and European community.
Definition
Biological diversity refers to the variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequency. For biological diversity, these items are organized at many levels ranging from complete ecosystems to the chemical structures that are the molecules basis of heredity. Thus the term encompasses different ecosystems, species, genes and their relative abundance.
1.3.2Types of Biodiversity
The term biodiversity includes three different aspects, which are closely related to each other. Following are the types of biodiversity:
Genetic Diversity
It refers to the variation of genes within the species. This constitutes distinct population of the same species or genetic variation within population or varieties within a species.
Species diversity
It refers to the variety of species within a region. Such diversity could be measured on the basis of number of species in a region.
Ecosystem Diversity
In an ecosystem, there may exist different landforms, each of which supports different and specific vegetation. Ecosystem diversity is difficult to measure since the boundaries of the communities, which constitute the various sub ecosystems, are elusive.
Ecosystem diversity could best be understood if one studies the communities in various ecological niches within the given ecosystem; each community is associated with definite species complexes. These complexes are related to composition and structure of biodiversity.
Agro-Biodiversity
The agricultural biological diversity more commonly referred to as the agro-biodiversity has been fast emerging as a strong, evolutionary divergent line from the biodiversity, which deals with the life forms at large. It has been specifically recognized to differentiate between concern for ecosystems versus agro-ecosystems, wild forest flora and fauna versus agriculture related plants, reptiles, insects, avian and microbes; in situ conservation of wild forms versus on farm conservation of landgraves and traditional/ primitive cultivars or ex-situ conservation of plant genetic resources, etc.
Agro-biodiversity in a traditional farming system is as follows (adopted from Altieri, 1991 and UNDP, 1995):
Rich in plant and animal species
A wide diversity of niches in the local environment utilized
Reuse of organic residues, consuming biomass enabled
Ecosystem functions, such as pest, weed and disease management enhanced
Locally available resources consumed to an advantage
Reduction of risk and optimization of resources use
Associated with farmers time tested local knowledge about resources.
1.3.3Biodiversity at Global Levels
It is estimated that there exists 5-30 million species of living forms on our earth and of these, only 1.5 million have been identified and include 3,00,000 species of green plants and fungi, 8,00,000 species of insects, 40,000 species of vertebrates and 3,60,000 species of micro-organisms.
Recently it has been estimated that the number of insects alone may be as high as 10 million, but many believe it to be around 5 million.
The tropical forests are regarded as the riches in biodiversity. According to the opinion of the scientists more than half of the species on the earth live in moist tropical forests, which is only 7% of the total land surface. Insects (80%) and primates (90%) make up most of the species.
Table 1.1 : Estimated number of species worldwide
Taxonomic Group / Number of SpeciesBacteria / 3600
Blue Green Algae / 1700
Fungi / 46983
Bryophytes / 17000
Gymnosperms / 750
Angiosperms / 250000
1.3.4Status in India
During the last few years, the subject of conservation of biological diversity has attracted considerable attention at the national and global levels. India is a rich centre of biodiversity and has contributed many economic plants to the world and many useful genes for genetic upgrading of cultivated plants and domesticated animals.
India has a land mass of 329 million hactares with a diversified eco-geographical regions. Almost all types of habitats available in the world are found in India. Ther are two biogeographical realms in India and it is the confluence of floras and faunas of Africa, Mediterranean, European, Sino-Japanese and Malayan rgions. As a result, we have a rich biological diversity (Gadgil, 1992).
Plant Species diversity
At present 1.7 million species have been recorded so far in the world (Global Biodiversity, 1995). India’s contribution to this record stands at 7 %. Surveys conducted so far have inventorised over 47,000 species of plants and over 89,000 species of animals. Survey and inventorisation of India’s biodiversity is still far from complete especially the lower groups of plants and invertibrate animals (Table 1.2).
Table 1.2 : India’s Biological Wealth
Plant Taxa / Species / Animal Taxa / SpeciesBacteria / 850 / Protista / 2577
Viruses / Unknown / Mollusca / 5070
Algae / 6500 / Arthropoda
(Insecta, Crustacea etc.) / 68389
Fungi / 14500 / Other Invertebrates / 8329
Lichens / 2000 / Protochordata / 119
Bryophytes / 2850 / Pisces / 2546
Pteridophytes / 1100 / Amphibian / 209
Gymnosperms / 64 / Reptilian / 456
Angiosperms / 17500 / Aves / 1232
Mammalian / 390
Total / 45364 / Total / 89317
Based on the available data, India ranks 10th in the world and 4th in Asia in plant diversity and ranks 11th in the number of Angiosperm species (table 1.3). India ranks 10th in the number of mammalian species and 11th in the number of endemic species of higher vertebrates in the world.
Table 1.3 : Number of angiosperm species in different countries.
Country / Angiospermic speciesBrazil / 55000
Colombia / 45000
Ecuador / 29000
China / 27000
Mexico / 25000
Australia / 23000
South Africa / 21000
Indonesia / 20000
Venezuela / 20000
Peru / 20000
India / 17000
Floristic status
As noted earlier 47,000 species of plants representing about 12 % of the recorded world’s flora have already been identified. Comparative statement of recorded number of plant species in India and the world is given in Table 1.4.
Table 1.4 : Comparative statement of Recorded number of
plant species in India.
Plant Taxa / Species / Percentage of India to the WorldIndia / World
Bacteria / 850 / 4000 / 21.25
Viruses / Unknown / 4000 / -
Algae / 6500 / 40000 / 16.25
Fungi / 14500 / 72000 / 20.14
Lichens / 2000 / 17000 / 11.80
Bryophytes / 2850 / 16000 / 17.80
Pteridophytes / 1100 / 13000 / 8.64
Gymnosperms / 64 / 750 / 8.53
Angiosperms / 17500 / 25000 / 7.00
Flowering plants accounts nearly 17,500 among 45,000 species of plants. The important economic species includes rice, sugar cane, coix, beans, cowpeas, banana, Citrus, mango, coconut, cardamoms, nutmeg, tea, cotton, jute, colocasia, pepper, ginger, Rhododendron, Jasmines, bamboos, Orchids, betel leaf etc.
Two regions of our country harbours maximum diversity, they are North-East and Sourth-West India. The North- East region is a very active centre of evolution and has diversity for a number of plants like Rhododndron, Camelia, Magnolia, Buddleia, etc. (Khosoo, 1991).
On the basis of distribution pattern of plants, Good (1953), divided plant wealth into 37 floristic zones. With in these zones, pockets of diversity of plants species arose and they were domesticated by human kind during the past 10,000 years.
During these years enormous variability was genertated because of mutation, recombination and selection process. The result being complex variation pattern in plants. These evolved plants bear little or no resemblance with their ancestorsss.
Endemic Species
Every major habitat, from areas of heavy rainfall to the dry desert, from coldest to the hottest climatic conditions, from highest elevation down to the sea level is found in the country. India has a rich endemic flora.
Endemism of Indian biodiversity is significant. About 4950 species of flowering plants or 33% of this recorded flora are endemic to the country. These are distributed over 141 genera belonging to 47 families. These are concentrated in the floristically rich areas of North-East India, the Western Ghats, North-West Himalayas and the Andaman & Nicobar Islands.
The Western Ghats and Eastern Himalayas are reported to have 16000 and 3500 endemic species of flowering plants, respectively. These areas constitute two of the 34 hot spots identified in the world.
Cultivated plants
Indian region alone has given to the world nearly 167 economical plants whose centre of origin/ diversity lie in India along with their 320 species of wild relatives and land races.
India is considered to be the centre of origin of rice, sugar cane, minor millets, pigeon pea, brassicas, rice-bean, Asiatic vignas, egg plant, banana, citrus, mango, cardamom, jack fruit, jute, edible diascorea, black pepper, seed amaranths, turmeric, ginger, several umbellifers and cucurbits, bittergourd, colacasia, okra, coconut, bamboo, taro, indigo, sun hemp, gooseberries and many herbal drugs, rhododendron, jasmine, some orchids and betel nut. This remarkable diversity of life-forms in a single country is because of the great diversity of ecosystems.
The gene bank of National Bureau of Plant Genetic Resources (NBPGR) has a collection of over 1,59,080 varieties. The details of the active germplasm holding and base collections of NBPGR are given in Table 1.5.
Table 1.5 : Active germplasm holding and base collections at NBPGR.
Crop groups / Activegermplasm / Base collection holdings
Cereals / 12086 / 43409
Pulses / 38695 / 22269
Millets & Minor Millets / 10349 / 14488
Oilseeds / 19808 / 14278
Vegetables / 12146 / 5681
Medicinal & Aromatic Plants / 870 / 942
Pseudocereals / 4739 / 736
Tuber Crop/ Spices / 2053 / -
Forage Crop / 4060 / -
Horticultural/ Ornamentals / 22212 / -
Fibre Crops / - / 3212
Released crop Varieties / - / 904
Reference Samples
(Medium Term) / - / 53161
Total / 107018 / 159080
Wild relatives of Crops
There are several hundred species of wild crop relatives distributed all over the country. A major centre for wild rice is the eastern peninsular India, i.e., West Bengal, Orissa and Andhra Pradesh. The North-Eastern hills and Tamil Nadu hills are rich in wild relatives of millets. Wild relatives of wheat and barley have been located in the western and North-Eastern Himalaya. Table 1.6 gives the statement of wild relatives of crops recorded so far.
Table 1.6 : Wild relatives of crop
Crop / No. ofWild relatives
Millets / 51
Fruits / 104
Spices and condiments / 27
Vegetables and pulses / 55
Fibre crop / 24
Oil seeds, tea, coffee,
tobacco, & sugarcane / 12
Medicinal plants / 3000
1.3.5Utilization of plant biodiversity
Biological resources contribute much to the social and economical development of the nation. Utilizing the species for industry and medicine and developing new products for national and international market provides good opportunities. Greater agricultural production and prevention of diseases and pests are also important. Biological and genetic diversity are fundamental to the proper functioning of any ecosystem and hence to human welfare.
The most important contribution of the earth’s biota is to maintain the ecosystem ability to provide essential life support functions, e.g. fixation of solar energy. Genetic resources are most precious asset. They are nature’s tool for harvesting solar energy and processing mineral resources in to food, fibre, fertilizer etc. They are crucial for human survival in the physical environment. They are the result of evolution over million of years.
Biological resources are active entities and extremely vulnerable. Once they are lost, they can not be replaced at any cost.
Success of genetic engineering depends upon genes (the basic building blocks) from plants, animals and micro-organisms. Therefore, ensuring success in genetic engineering, we need to conserve biological resources.
Genetic diversity is heritable with in and between of the species of a genus. Genetic diversity is very critical to our agriculture, horticulture, forestry and animal husbandry. Many germplasms from India have made many distinctive contributions in plant improvement. Broadly speaking biological diversity satisfies human needs in two different ways, direct and indirect.
Biodiversity will not only help in increasing agricultural productivity but also in developing disease resistant varieties. It was evident in the early 1970’s when epidemic called grassy stunt virus destroyed more than 1,60,000 ha of rice in Asia, could be controlled from a single sample of wild rice Oryza nivara from Central India, which was found to be the only known genetic source of resistance to the grassy stunt. Besides 20 major genes from wild for disease and pest resistance are used in rice improvement programmes.
Besides food and other basic needs, human health has gained priority in welfare programmes. Once all medicines used to come from plant and animal resources. Worldwide medicines from plants are now worth 40 billion dollars a years. Even now 80 percent people in the developing countries depend upon traditional medicines.
Indirect benefits include nutrient trapping, maintaining water cycles, soil production and protection of soil, absorption and break down of pollutants, provision of recreational, aesthetic, scientific, spiritual etc.
It is estimated that more than 25 percent of all medicines available today are derived from tropical plants. Over 40 percent of Pharmaceuticals available in the USA depend on natural sources.
In 1960, a child contracting Leukemia had one chance in five survival, since then scientists have developed a drug – Vincristine from a plant of the tropical forests, Vinca rosea, that now allow leukemia sufferer four chances in five of survival.
The National Cancer Institute near Washington DC has screened 29,000 plant species, and at least five may come to rival vincristine. The institute believes that mass extinctions of species could represent a serious back to the future of anti-cancer campaigns.
Among other medical products the “pill” that is swallowed by million women each day contains sex hormone combination derive from a Mexican forest yam. Over-the-counter sales of the pill are re worth one million dollar a year.
Prioritization approach and patenting
The list of species to be conserved is ever-increasing. There are also other plants and animals, which are likely to be important in future. There is a whole range of threatened/ endangered plants numbering around 2000 in India. Resource constraints do not allow, all these to be saved and it would be totally unrealistic even to attempt this.
Approach of prioritization, both of economic importance and academic interest are needed. With in a country different states could select an indigenous mammal, bird, wild flower and a tree. These could then be declared as state mammal, bird, flower and tree. Rajasthan state has declared Great Indian Bustard (Ardeotis nigriceps) as state bird and Khejri (Prosopis cineraria) as state tree. Based on indepth study, an agreed list of species could be arrived and the best way of conservation method(s) to b employed.
Patents are meant to stimulate innovation and increase public perception about new ideas and inventions. A patent is, therefore, a limited monopoly for a given number of years during which patentee has exclusive rights to the invention. In view of expanding role of “Genetic raw materials” is genetic engineering, patenting of cultivars by multinationals has to be looked in a proper manner. During patenting, legal, economical and technical issues may be taken into account.
Each country needs to critically review their network of conservation areas, together with their future plans. The conservation of just wild animals alone will not succeed unless, the carefully chosen ecosystem need to be taken up for conservation purpose. Special attention must be paid to forests having large biological diversity of plants and animals.