lecture Jagannath University Department of agriculture

Lecture

1. Lecture 4

2. Domestication Domestication means bringing wild species under human management. This is the first step in development of cultivated plants. The example of domestication is the kala jeera, a perennial spice was domesticated during 1990 in Himachal Pradesh and is being cultivated as an orchard crop.

3. Selection under Domestication When different genotypes present in a population reproduce at a different rates, it is called selection. Population: It may be defined as the group of individuals, which mate or can mate freely with each other. Selection is of two types: Natural Selection Artificial Selection

4. Natural Selection: Selection due to natural forces like climate, soil, biological factors e.g., diseases, pests, insect etc. and other forces of the environment is called natural selection. It occurs in natural populations i.e. wild species and wild forms. Generally all the genotypes of the population reproduce, the population become more adapted to the prevailing environment and considerably variability is retained. Natural selection may be seen to operate through two mechanisms (a) Environment selection (b) Competition Environment selection acts against all such genotypes that are unable to cope with the environmental stresses and are also able to reproduce. Natural selection through competition occurs in crop populations, where a plant takes up more water, nutrients or light than other.

5. Artificial Selection Artificial selection is carried out by humans and is confined to domesticated species. It allows the selected plants to reproduce, makes plants more useful to humans and generally leads to marked decline in genetic variability in the selected progenies/populations.

6. Changes in plant Species under domestication Elimination of or reduction in shattering. Elimination of dormancy. Decrease in toxins. Plant type has been extensively modified. In several crop species, there has been a decrease in plant height e.g., cereals, millets etc. In some species on the other hand, there has been an increase in plant heiht under domestication e.g. jute, sugarcane, forage grasses etc. Life cycle has become shorter.

7. Increase in size of their grains or fruits. Increase in economic yield. Asexual reproduction has been promoted under domestication. Preference for polyploidy. Shift in the sex form: in many dioecious fruit trees, bisexual forms have developed under domestication. Variability within variety has drastically decreased under domestication.

8. Acclimatization The process that leads to adaptation of a variety, line or population to a new environment is known as acclimatization. The acclimatization is the result of natural selection The extent of acclimatization is determined by Mode of pollination The magnitude of genetic variability present in original population The duration of life-cycle of the crop mutation

9. Factors Cross pollination leads to a far greater gene recombination than self pollination. As a result, cross-pollination is more helpful in acclimatization than self pollination. Genetic variability is the pre requisite for acclimatisation , therefore, the greater the amount of genetic variability present in original population, the more is the extent of acclimatization. Life cycle duration is important because an annual crop would produce several generations by the time produces one generation.. Each generation would produce new gene combinations thereby facilitating acclimatization. Mutation plays a role in acclimatization but it becomes imp only when the period of acclimatization is very long.

10. Plant Introduction It consist of taking a genotype of plants into new area or region where they were note being grown before. Plant introduction involve new varieties of a crop already grown in an area, wild relatives of the crop species or totally new crop species. Examples of within country introduction are the popularization of cultivation of grape in Haryana, of wheat in West Bengal and of rice in Punjab.

11. Types of Plant Introduction Primary Introduction: When the introduced variety is well adapted to the new environment, it is released for commercial cultivation without any alteration in its genotype, this constitute primary introduction. Introduction of semidwarf wheat varieties Sonara 64, Lerma Rojo and semidwarf rice TN1, IR8, IR28, IR36 are some examples of primary introduction

12. Secondary Introduction The introduced variety may be subjected to selection or used in a hybridization programme to develop a superior variety, it constitutes secondary introduction. Examples of secondary introduction are Kalyan Sona and Sonalika wheat varieties selected from materials introduced from CIMMYT Mexico.

13. Plant Introduction Agencies in India National Bureau of Plant Genetic Resources (1976)]: This bureau is responsible for introduction and maintenance of germplasms of agricultural and horticultural plants. NBPGR functions as the central agency for the export and introduction Forest Research Institute, Dehradun.

14. Procedure for Plant Introduction Introduction of germplasm consists of the following steps: Procurement Quarantine Cataloguing Multiplication Distribution

15. Procurement of Germplasm: Any individual or institution can introduce germplasm in India, but all the introductions must be routed through NBPGR, New Delhi. The individual/institution concerned may follow any one of the following two routes for this purpose It/He may make direct request to individual or institution abroad, who has desired germplasm to send it to him through NBPGR, New Delhi. Alternatively, whenever the concerned individual/institution is unable to procure the desired germplasm on his/its own, a request for import of the required germplasm is submitted to NBPGR.

16. Gift, Purchase or Collection: Germplasm may be obtained from other countries As gifts from individuals/institution In exchange of germplasm provided by NBPGR, New Delhi to the concerned individual/institution By purchase Through exploration

17. Propagules: The plant part used for propagation of a species is known as propagules. The nature of propagules varies from species to species, they are used for germplasm exchange. The plant parts used for introduction may be seeds, tubers, runners, suckers, stolons , bulbs, rooted cutting, bulbs or seedlings. Seeds are generally obtained by surface mailoften packed and sealed in thick paper envelopes.

18. 2) Quarantine Quarantine means to keep materials in isolation to prevent the spread of diseases etc. present in them to other materials. According to destructive insects and pests act 1914, all plants produce imported in India must be free from diseases, insect pests and weeds. The process of quarantine at NBPGR, New Delhi takes at least three weeks

19. 3) Cataloguing Each germplasm accession is given an accession number. In India, this number is prefixed with either IC (Indigenous collection), EC (exotic collection) or IW (indigenous wild) Information about the species and variety names of accessions, place of origin, adaptation and their various features or descriptors are also recorded.

20. 4) Evaluation It is done by special computer programmes 5) Multiplication and Distribution The germplasm accession requested by breeders/researchers are multiplied and supplied to them, usually without cost. This is the important activity of gene banks since it is the very purpose for which it is established.

21. Purpose of Plant Introduction Entirely New Crops: e.g gobhi sarson , soybean New varieties : e.g. Sonara 64 and Lerma Rojo of wheat and TNI and IR8 in rice Utilization in crop improvement programmes : Often the introduced materials are used for hybridization with local varieties e.g. Pusa Ruby tomato was derived from a cross between Meeruty and Sioux Saving a crop from a disease or pest e.g. coffee was introduced in south America from Africa to prevent losses from leaf rust. Utilization in Scientific studies.

22. Merits of Plant Introduction Provides entirely new crop It provides superior varieties either directly after selection or through hybridization. Quick and economical. Crops may be introduced from new disease free areas to protect them from damage e.g. coffee and rubber

23. Demerits Weeds e.g. Argemone Mexicana , Phylaris minor Diseases e.g Late blight from Europe in 1883 Insect Pests e. g. Potato tuber moth from Italy in 1900 Ornamentals turns into weeds e.g Lantana camara Threats to ecological balance e.g Eucalyptus spp. From AustraliaIn India deplete the subsoila d water reserves