Introduction
Where would we have been had it not been for the discovery of the art of collecting seeds and cultivating them for food? Life would surely have been very different!
Early man was a food gatherer, depending on nature for all his needs. He gradually moved on to being a food grower with the discovery of agriculture, and settled down in one place, learning to live in a group. This was the beginning of civilization as we know it today.
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Early knowledge of agriculture was an accumulation of experiences that were passed on from father to son. Some of these have been preserved as religious commandments and some in the ancient inscriptions. There is evidence to show that as early as 2000 BC the Egyptian civilization followed particular dates for sowing and reaping. Some Greek and Roman classics give instructions on how to get a higher yield.
The development of agriculture made it apparent that more food could be extracted from a given area of land by encouraging useful and hardy plant and animal species, and discouraging others.
At the turn of the 19th century, a movement began in central Europe to train farmers in specific farming skills. A truly scientific approach was begun by Justine von Liebig of Darmstadt who in his classic work introduced the systematic development of agriculture science. From the 19th century onwards plant production became a scientific discipline.
In the early 20th century, the legendary work of Gregor Mendel laid the foundation of modern day genetics. His work explained the basics of inheritance in terms of the factor we today call genes.
Apart from selection and hybridization, new and innovative techniques such as genetic engineering that aid plant breeders have been developed in the recent past. One example of this is BtCotton. With advances in human and plant biology, more intricate details about the cell – the basic unit of life – were illuminated. The possibility of raising whole plants from various plant tissues, commonly know as tissue culture, has thrown open the doors for expedited evolution both in terms of generation of genetic variability and multiplication of elite plant types. The knowledge of the wonder molecule DNA has also opened a new area of plant breeding research. These new technologies have been collectively referred to as biotechnology. It is a collective effort for plant breeding in the future and will compliment man's crusade for more and better food. In India, the reen Revolution saw the rapid progress of agriculture and the application of different methods to enhance production. Biofertilizers have been proven to be more environmentally friendly fertilizers that do not cause harm to life. Bioremediation methods have been used to clear oil spills using bacteria.
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Biotechnology is short for biological technology. Technology is the ability to better utilize our surroundings. Biotechnology applies the same principles to living organisms as do other technologies. Biotechnology can be defined as the application of our knowledge and understanding of biology to meet practical needs. It is as old as the growing of crops. Today’s biotechnology is largely identified with applications in medicine and agriculture based on our knowledge of the genetic code of life. Fermentation, used in making bread, beer, and cheese, is an example of biotechnology. Modern biotechnology simply allows scientists to be more specific in their work.
Different types of crops have been produced using the molecular tools of biotechnology and are beginning to be utilized in agricultural systems all over the world. At the same time, an increasing number of farmers are adopting sustainable cultural practices.
Biotechnology has the potential to assist farmers in reducing on-farm chemical inputs and produce value-added commodities. Conversely, there are concerns about the use of biotechnology in agricultural systems including the possibility that it may lead to greater farmer dependence on the providers of the new technology.
Plant Breeding
As a part of agriculture, man started rearing plants and animals to meet his requirements. This is when humans started to learn how to influence the process of natural evolution so as to breed plant or animals.
Slowly and gradually, this process of expedited evolution, through selection and cultivation of plants, acquired the form of a routine endeavor—what we today call ‘plant breeding’. In this, heredity, which refers to the passage of various characteristic features from the main plant (the parent) to the plantlets (the progeny), plays an important role. The effects of heredity had been apparent to early man and he had taken advantage of them ever since the advent of agriculture.
Various methods have evolved in plant breeding. One of the most important methods is that of selection.
The ability to choose gave birth to the idea of selection. This is the most primitive and by and large the most successful method of plant breeding. Selection as a part of plant breeding started with the domestication of plants by early man. Domestication refers to the process of bringing wild species under human management. Not all selection over the years have been human influenced—many of the important crop species have resulted from the natural selection process, which is an integral part of evolution. As human knowledge of agriculture grew, man started shuffling crop species from one geographical terrain to another, thus making new introductions.
The first prerequisite of selection is the availability of variability, i.e. different types of forms. After a variable population is recognized, individuals that are the best performers for the desired feature, say fruit size in the case of tomatoes, are chosen and the rest of the population is discarded or rejected. The progeny of the selected individuals is grown further and again screened for the desired feature. This process is repeated until a uniform plant population is attained which has the best-desired characters. Eventually, a desired uniform crop variety is produced by this successive selection followed by multiplication of the selected individuals.
Selecting higher yielding plant varieties is no easy task. Various tools have been devised to deal with plant selection. In fact, the birth of genetics as an independent discipline in plant science started with some clever mathematical computations. This brainchild of yesteryears is now an important branch of genetics known as biometrics. Biometrics is defined as the application of statistics in biology. This has contributed greatly to the development of various systems based on which selection of plants is done. There are various methods by which plant selection is carried out, namely selection for uniform plants, known as pure line selection; selection from field-grown plants, known as bulk selection or mass selection; and selection from a well-documented list of parentage, commonly known as the pedigree system. Overall, the hallmark of selection lies in human ability to chose the best plants from a cluster of many.
Hybridization
In traditional terms, hybridization refers to the union of the male and the female gamete to produce a zygote. In plant science, hybridization also refers to the crossing or mating of two plants. The story of scientific hybridization of crop plants started with J G Kolreuter, who in 1761 published his work on the scientific bases of hybridization. Since then, hybridization followed by selection, has been the major tool of plant breeding.
In his quest to find more variability, man started experimenting with hybridization of plants so as to achieve the perfect plant type. This process was actually the beginning of expedited evolution since it led to the formation of new plant types artificially or due to human intervention at a much faster pace than it would have happened in nature. For example, the bread wheat that we eat today has taken about 500 years to evolve to its present form through human intervention. This form of wheat would have taken thousands of years to evolve had it been left to the natural evolution process.
Ways in which hybridization is used
Some of the ways in which hybridization has been exploited in breeding crop plants are given below
Combination breeding: The main aim of combination breeding is to transfer one or more characters into a single variety or plant type from many others. For this, an existing plant variety may be used as the recipient parent while many other crop varieties or wild relatives may contribute as donor parents. The most commonly used method to achieve this goal is known as the backcross method. The plant type in which the character or the trait is being transferred is known as the recipient parent and the other as the donor parent. For this, the two plants are mated or crossed and the progeny is screened for the desired trait. The progeny plants possessing the desired trait are then selected and crossed back to the recipient parent. This process is repeated until the desired plant type having all the characteristics of the recipient in addition to the trait being transferred is finally obtained. This exercise is known as backcrossing. Backcrossing involves both hybridization and selection.
Hybrid varieties: Plant scientists exploit the characteristic feature of better yielding ‘hybrids’ in plants. Hybrid vigour, or hetrosis as it is scientifically known, exploits the fact that some offspring from the progeny of a cross between two known parents would be better than the parents themselves. Many hybrid varieties of several crop species are being grown all over the world today. An example of this is the hybrid tomatoes that we eat commonly. The philosophy of hybridization has been extended from ‘within the same species or genera (the same type of plants)’ to ‘different species or genera (totally different plants)’. This is known as wide or distant hybridization. Wide hybridization has helped breeders to break what is known as the species or genera barrier for gene transfer, i.e. it has helped breeders to transfer beneficial characteristics from wild and weedy plants to the cultivated crop species.
The Green Revolution
The world's worst recorded food disaster occurred in 1943 in British-ruled India. Known as the Bengal Famine, an estimated 4 million people died of hunger that year in eastern India (which included today's Bangladesh). Initially, this catastrophe was attributed to an acute shortfall in food production in the area. However, Indian economist Amartya Sen (recipient of the Nobel Prize for Economics, 1998) has established that while food shortage was a contributor to the problem, a more potent factor was the result of hysteria related to World War II, which made food supply a low priority for the British rulers.
When the British left India in 1947, India continued to be haunted by memories of the Bengal Famine. It was therefore natural that food security was one of the main items on free India's agenda. This awareness led, on one hand, to the Green Revolution in India and, on the other, legislative measures to ensure that businessmen would never again be able to hoard food for reasons of profit.
The Green Revolution, spreading over the period from1967/68 to 1977/78, changed India’s status from a food-deficient country to one of the world's leading agricultural nations. Until 1967 the government largely concentrated on expanding the farming areas. But the population was growing at a much faster rate than food production. This called for an immediate and drastic action to increase yield. The action came in the form of the Green Revolution. The term ‘Green Revolution’ is a general one that is applied to successful agricultural experiments in many developing countries. India is one of the countries where it was most successful.
There were three basic elements in the method of the Green Revolution
 | Continuing expansion of farming areas |
| | Double-cropping in the existing farmland |
| | Using seeds with improved genetics. |
The area of land under cultivation was being increased from 1947 itself. But this was not enough to meet the rising demand. Though other methods were required, the expansion of cultivable land also had to continue. So, the Green Revolution continued with this quantitative expansion of farmlands.
Double cropping was a primary feature of the Green Revolution. Instead of one crop season per year, the decision was made to have two crop seasons per year. The one-season-per-year practice was based on the fact that there is only one rainy season annually. Water for the second phase now came from huge irrigation projects. Dams were built and other simple irrigation techniques were also adopted.
Using seeds with superior genetics was the scientific aspect of the Green Revolution. The Indian Council for Agricultural Research (which was established by the British in 1929) was reorganized in 1965 and then again in 1973. It developed new strains of high yield variety seeds, mainly wheat and rice and also millet and corn.
The Green Revolution was a technology package comprising material components of improved high yielding varieties of two staple cereals (rice and wheat), irrigation or controlled water supply and improved moisture utilization, fertilizers, and pesticides, and associated management skills.
Benefits
Thanks to the new seeds, tens of millions of extra tonnes of grain a year are being harvested.
The Green Revolution resulted in a record grain output of 131 million tonnes in 1978/79. This established India as one of the world's biggest agricultural producers. Yield per unit of farmland improved by more than 30% between1947 (when India gained political independence) and 1979. The crop area under high yielding varieties of wheat and rice grew considerably during the Green Revolution.
The Green Revolution also created plenty of jobs not only for agricultural workers but also industrial workers by the creation of related facilities such as factories and hydroelectric power stations.
Shortcomings
In spite of this, India's agricultural output sometimes falls short of demand even today. India has failed to extend the concept of high yield value seeds to all crops or all regions. In terms of crops, it remains largely confined to foodgrains only, not to all kinds of agricultural produce.
In regional terms, only the states of Punjab and Haryana showed the best results of the Green Revolution. The eastern plains of the River Ganges in West Bengal also showed reasonably good results. But results were less impressive in other parts of India.
The Green Revolution has created some problems mainly to adverse impacts on the environment. The increasing use of agrochemical-based pest and weed control in some crops has affected the surrounding environment as well as human health. Increase in the area under irrigation has led to rise in the salinity of the land. Although high yielding varieties had their plus points, it has led to significant genetic erosion.
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