Preface Plant Breeding is a scientific exercise to tap the natural variability resulting as a  consequence of evolution due to natural selection or to induce variability by genetic manipulation, introduction and domestication of the plant population and to evolve products of economic value for mankind. As the demand for these basic requirements increased due to population growth, man started selecting improved versions of plant products for cultivation to realise increased production. The art of plant breeding evolved into a science with the rediscovery of Mendels laws and their application. Today Plant Breeding aims at developing varieties or hybrids that are capable of yielding the maximum product of improved quality per unit area of land in unit time or duration, efficiently utilising the available or added plant nutrients and possessing stability in performance with resistance or tolerance to biotic and abiotic stresses. The challenge for plant breeders now, is to determine how best the multitude of available information can be utilised in the improvement of crop performance and production. The purpose of bringing out this publication is to link latest available advancement on stress breeding, horticultural crop breeding, forest tree improvement, genetic resources management with tools and techniques like molecular markers, genetic engineering, tissue culture, bioinformatics with policies on  plant breeders and farmer’s rights and seed policy. This book comprises of 15 chapters contributed by experienced and recognised experts   all around the world, whom have deep knowledge and research experience in modern plant breeding. This book is very useful to researchers and students in the field of genetics and plant breeding using biotechnological tools who may aware of the impact of different aspects of plant breeding in crop improvement.

Crop improvement Crop improvement refers to the genetic alteration of plants to satisfy human needs. It deals with the improvement of crops and production of new crop varieties, which are far superior to existing types in all characters. In pre-history, our ancestors in various parts of the world brought into cultivation a few hundred species from the hundreds of thousands available. In the process they transformed elements of these species into crops though genetic alterations that involved conscious and unconscious selection, the differential reproduction of variants. Through a long history of trial and error, a relatively few plant species have become the mainstay of agriculture and thus the world’s food supply. This process of domestication involved the identification of certain useful wild species combined with a process of selection that brought about changes in appearance, quality, and productivity.

Crops plants are broadly classified into two groups based on their mode of reproduction viz. sexually propagated and asexually propagated. In sexually propagated crops seeds are the primary propagules and it is produced by the fertilization of male and female gametes. Whereas, asexual reproduction or clonal reproduction covers all those modes of multiplication of plants where normal gamete formation and fertilization does not take place and vegetative propagules are the means of reproduction. Since sexual reproduction involves meiosis, segregation and recombination, the creation of variation is a continuous process which is inevitable in these crops. On the other hand, in asexual propagation progenies are identical to the parent clones and they are genetically similar without any variation and they reproduce via mitosis. The most important vegetatively propagated food crops are potato, sugar cane, cassava, sweet potato, yam, plantain/banana, and fruit trees. Other crops with asexual propagations are some ornamentals, grasses, and forages.

The primary purpose in plant breeding is to develop better varieties. In order to realize the potential benefit from an improved variety, it should be distributed widely and sufficient seed must be produced so that the variety can be grown on farms in the areas to which it is adopted.  Otherwise much of the breeders work would be wasted. Variety is a synonym of cultivar and has been defined in the International Code for the Nomenclature for cultivated plants (Anon 1980.) in article 10. ‘’The international term cultivar denotes as assemblage of cultivated plants which is clearly distinguished by any characteristics (morphological, physiological, cytological, chemical or others) and which, When reproduced (sexually or asexually) retains its distinguishing characters”. Indian Seeds Act, under its sub-section 16 of section 2 defined variety as “a sub-division of a kind identifiable by growth, yield, plant, fruit, seed or other characteristic”. Both definitions emphasize that variety should be distinguishable from others and capable of retaining its distinguishable features under multiplication. Therefore production of genetically pure and otherwise good quality pedigree seed is an exacting task requiring high technical skills and comparatively more financial investment. During seed production strict attention must be given to the maintenance of genetic purity and other qualities of seeds in order to exploit the full dividends sought to be obtained by introduction of new superior crop plant varieties.

A. Salinity Salinity is a predominant problem affecting crop productivity. Over 800 million hectares of land on earth are saline. This accounts for more than 6% of the total land mass on earth. Salinity is a global problem and is prevalent especially in the arid and semiarid regions, where leaching of salts is poor due to low rainfall or irrigation. Brine-affected soil occurs due to natural causes such as weathering and deposition of oceanic salts (eg. recently tsunami in India). In addition, human interference with the environment such as deforestation and/or desertification has resulted in the rising of water table, thus increasing the salt concentration in the root zone. This excess salinity poses a threat to sustainable crop production.

In general, disease means an impairment of health or a condition of abnormal functioning. Plant disease is an abnormal deviation from the normal physiological functioning of the plants their by it causes quantitative and/or qualitative losses. Disease may caused by biotic agents (infectious) like fungi, bacteria, viruses, viroids, phytoplasma, spiroplasma, fastidious bacteria, protozoa, nematodes and parasitic higher plants or abiotic agents (non-infectious) like extreme environmental factors includes temperature, light, soil moisture, atmospheric humidity, environmental pollutants, carbon-dioxide concentration, soil nutrient deficiency, acid rain, soil pH and herbicides. 

Crop varieties are domesticated since civilization, and their continued cultivation depends on continuous breeding programmes for insect, disease and other stress resistance. World wide, insects and their associated problems cause threat to crop production. Many crops suffer from insects, which may be in the form of direct damage by feeding or indirectly by the transmission of diseases by insects as vectors. Until now, chemical crop protection is seen as the major way to combat these problems. However, insects develop resistance to the insecticides very quickly. Apart from controlling pest insects, insecticides also affect beneficial insects, such as predators and parasitoids of the pest insect, pollinators, and harmless fauna, thus upsetting ecological balance results in many unwanted problems. Hence, the best strategy is to prevent the problems that occur. The most economical and environmental friendly way of controlling the insect pests of crops would be through host-plant resistance (HPR). Resistant plants help farmers to grow crops with minimal use of chemicals. This will lead to a reduction in the cost of production, thereby increasing the profit margin for farmers and thus importance of breeding for pest resistance is manifested.

Horticulture, which includes fruits and vegetables, plantation crops, spices, flowers, and medicinal and aromatic plants, has proved beyond doubt its potentiality for gainful diversification. One of the significant developments is that, horticulture has moved from rural confine to commercial production. Recently horticulture has emerged as one of the best option of diversification for effective land use planning and to achieve inclusive growth. The achievement in the development of horticulture through crop improvement is laudable, as the sector now contributes more than 30 percent to GDP of agriculture and has maintained the growth rate of more than 5 percent during the last two decades.

The forest manager aims at producing maximum forest produce of desired quality from the unit forest area in a shortest possible period at a reasonable cost. There is a wide gap between production and requirement from forests. Increasing population and improved standard of living increases demand for forest products. Achieving this in a natural forest is more arduous job. Actual growing stocks in natural stand are poor in terms of vigour, size and quality. The regeneration from these poor stands will produce inferior quality trees. Hence management of forest is inevitable for its improvement.

Plant breeding is considered as current phase of crop evolution. It is a combination of art and science, which involves designers activity, conventionally, economically important traits dispersed in different parental lines are combined together to develop a new variety or cultivar and to change the genetic constitution of a plant to make it more suitable for human need with available scientific knowledge. Although plant breeding has been existing since time immemorial, modern plant breeding methods are based on scientific principles begins only with the rediscovery of Mendel’s laws of inheritance in 1900 and chromosomal theory of inheritance in 1902. Significant achievements have been made in crop improvement through phenotypic selections for agronomically important traits, considerable difficulties are often encountered during this process, primarily due to genotype-environment interactions.

Tissue culture is the culture and maintenance of plant cells or organs in sterile, nutritionally and environmentally supportive conditions (in vitro). Conventional breeding methods are the most widely used for crop improvement. But in certain situations these methods have to be supplemented with plant tissue culture techniques, either to increase their efficiency or to achieve an objective not possible through conventional methods.

As biotechnology increasingly affects almost all aspects of human life, it is essential that the science behind this technology is explained in simple terms to the public to eliminate the misconceptions that may inhibit its acceptability. The basic question that is often asked is what is a gene, a promoter and a terminator? Genes are the basic units of heredity, composed of DNA sequences, which are transmitted from parents to offspring and which, independently or in combination with other genes, control specific traits in an organism. These traits may be, for example, plant height, flower color, fruit and seed size together with regulatory processes, such as assimilate partitioning and drought resistance. Genes are the basis for both the similarity and differences that exist among organisms, and are transmitted from one generation to another.

Plant genetic resource (PGR) is fundamental to crop improvement programme and key to establish future food and nutritional security. In recent times there is a worldwide awakening about the conservation of natural resources viz., land, water and plant genetic resources for the sustainable development of mankind. With the increasing risk from the events like climatic change, natural resource degradation,habitat destruction and environmental pollution etc, now there is an worldwide  debate asking many questions - where the humanity is heading in the this 21st century? Whether the present form of indiscriminate growth pattern is sustainable over a long run?

Bioinformatics is a new science conceptualizing biology in terms of molecules and then applying informatics techniques derived from disciplines such as computer science, maths and statistics to understand and organize the information associated with these molecules on a large scale (Gerstein and Jansen, 2000). It is often defined as the application of computational techniques to understand and organize the information associated with biological macromolecules (Luscombe et al., 2001). It represents a new field at the interface of the twentieth-century revolutions in molecular biology and computers (Pevsner, 2000)

Two decades after India’s independence, during the 1960s, the formal seed sector in India was dominated by the Public sector. It was in 1961 that the National Seeds Corporation (NSC) was established under the Ministry of Agriculture and was at the centre of seed production of breeders, foundation and certified seeds and their quality control. In furtherance of their control in the seeds sector, the National Seeds Project (NSP) was undertaken by the Indian Government in 1967 along with the assistance of the World Bank. In the sixties, the traditional crop breeding and seed production programmes were significantly transformed and modernized with initiation of hybrid development programme in maize, sorghum and pearl millet and introduction, breeding and release of semi dwarf high yielding varieties of wheat and rice.  Indian Seeds Act was enacted in 1966 ensuring official release of varieties and their quality seed production

Significant transformation took place in the traditional variety improvement and seed production programmes in the sixties and modernized with initiation of hybrid development programme in maize, sorghum and pearl millet, as well as with the introduction, breeding and release of semi dwarf high yielding varieties of wheat and rice. To support the release of varieties and their quality seed production Indian Parliament enacted Indian Seeds Act in 1966. Subsequently, National Seeds Corporation was launched by Government of India for scientific growth of seed industry in the country. All these developments led to the green revolution and country attained self-sufficiency in food crops.