PB Ch 8. Plant Introduction

1.1  Definition

• Plant introduction is the process of taking a genotype or a group of genotypes into a new place or environment where they were not grown previously. Introduction may involve new varieties of a crop already grown in the area, wild relatives of the crop species, or a totally new crop species for that area.
• Examples:

•  Introduction of IRRI rice varieties into India
• Introduction of sunflower wild species from Russia
•  Introduction of oil palm into Tamil Nadu
• Introduction of wheat into West Bengal (previously not grown in the area)
• Introduction of grape cultivation into Haryana

Within-country movement of varieties from one environment to another also constitutes introduction, even though the material stays within the same country.

1.2  Types of Plant Introduction

A. Primary Introduction

• When the introduced variety or crop is well suited to the new environment, it is released for commercial cultivation without any alteration in the original genotype. The material is used directly as a variety.
• Examples

• IR-8, IR-20, IR-34, IR-50 rice varieties — introduced from IRRI, Philippines; suitable for Indian conditions and released directly
• Sonora 64 and Lerma Rojo — Mexican semi-dwarf wheats introduced directly by M.S. Swaminathan
• Taichung Native 1 (TN-1) — semi-dwarf rice introduced from Taiwan
• Oil palm varieties introduced from Malaysia
• Mashuri rice from Malaysia

B. Secondary Introduction

• The introduced variety is subjected to selection to isolate a superior variety, or it is hybridized with local varieties to transfer useful traits. This is much more common than primary introduction.
• Examples:

• Kalyan Sona and Sonalika wheat — selected from material introduced from CIMMYT, Mexico
• Pusa Ruby tomato — cross between Meeruti (local) and Sioux (introduction from USA)
• In soybean: EC 39821 introduced from Taiwan was subjected to selection and variety CO 1 was developed 
• In rice: ASD 4 crossed with IR-20 to get CO 44 suited for late planting 

1.3  History of Plant Introduction

Crop plants have traveled into new areas from their centres of origin throughout human history. This movement largely occurred with the migration of people. Much of it happened in prehistoric times. The GPBR 211 BAU source provides a useful historical account that is directly relevant to exam answers:

• Prehistoric period: Mung, mustard, pear, apple, and walnut were introduced from the Central Asian Centre of origin into various parts of India. Sesame, jowar, arhar, Asian cotton, and finger millet originated in Africa and traveled to India in prehistoric times.
•  ~1300 AD (Muslim invaders): Introduced cherries and grapes into India from Afghanistan. (Year is approximate — I am not fully certain of this date; please verify from agricultural history texts.)
• 16th century AD (Portuguese): Introduced maize, groundnut, chillies, potato, sweet potato, guava, pineapple, papaya, cashewnut, and tobacco into India. These are all American crops (New World) that the Portuguese encountered after Vasco da Gama's voyages. This is a well-established historical fact.
• East India Company: Brought tea and litchi from China. Also introduced cabbage, cauliflower, and other vegetables from the Mediterranean; annatto and mahogany from the West Indies.
• 19th century (Botanic Gardens): Calcutta Botanic Garden (established 1781) and Kew Botanic Gardens (England) played major roles. The Kew Gardens arranged the introduction of quinine (from Cinchona) and rubber (Hevea brasiliensis) trees from South America into India.

1.4  Plant Introduction Agencies in India

Historical Development of the Central Agency

• A centralized plant introduction agency was initiated in 1946 at IARI, New Delhi. The evolution of the agency:

• 1946: Plant introduction scheme started in the Division of Botany at IARI, funded by ICAR
• 1956 (Second Five Year Plan): Scheme expanded as the Plant Introduction and Exploration Organisation
• 1961: Made an independent division in IARI — Division of Plant Introduction
• 1976: Reorganized as the National Bureau of Plant Genetic Resources (NBPGR). The headquarters remain at IARI campus, Pusa, New Delhi.

Other Agencies Involved

• Forest Research Institute, Dehradun: Looks after introduction, maintenance, and testing of germplasm of forest trees.
• Botanical Survey of India (BSI, established 1890): Originally responsible for introduction and maintenance of botanical and medicinal plant materials. Currently, introduction and improvement of medicinal plants is coordinated by NBPGR.
• Central Research Institutes: Various ICAR central research institutes for specific crops (CRRI for rice, CTRI for tobacco, CPRI for potato, SBI for sugarcane, etc.) introduce, test, and maintain plant materials of their specific crops. Their activities are coordinated by NBPGR.

1.5  ICAR-NBPGR — National Bureau of Plant Genetic Resources

• NBPGR is the nodal agency for plant genetic resources management in India. It was established in 1976. Its headquarters are at IARI campus, Pusa, New Delhi.

Substations

Original substations representing different climatic zones:

• Shimla (Himachal Pradesh): Represents the temperate zone; approximately 2,300 m above sea level.
• Jodhpur (Rajasthan): Represents the arid zone.
• Kanya Kumari (Tamil Nadu): Represents the tropical zone. 
• Akola (Maharashtra): Represents the mixed climatic zone; was recently shifted from Amravati.
• Shillong (Meghalaya): A new substation established for collection of germplasm from North-East India, which has large genetic variability for rice, citrus, maize, and other species.

Functions of NBPGR 

• Introduces the required germplasm from counterpart agencies or institutions in other countries.
• Arranges explorations inside and outside the country to collect valuable germplasm.
• Responsible for inspection and quarantine of all introduced plant materials — all imported plant propagules are thoroughly inspected for weed seeds, diseases, and insect pests.
• Testing, multiplication, and maintenance of germplasm obtained through various sources — done either at the bureau's substations or by the relevant Central Research Institutes.
• Supplies germplasm, on request, to various scientists and institutions.
• Maintains records of plant name, variety name, propagating material, special characteristics, source, date, and other relevant information.
• Supplies germplasm to counterpart agencies in other countries.
• Publishes exchange and collection lists. 
• Sets up natural gene sanctuaries of plants where genetic resources are endangered.
• Improvement of certain plants — particularly medicinal and aromatic plants.

International Counterpart: IBPGR / Bioversity International

• International Board of Plant Genetic Resources (IBPGR) with headquarters at Rome, Italy, as the international agency responsible for plant introduction between countries. 
• It became IPGRI (International Plant Genetic Resources Institute) and later Bioversity International (now part of the CGIAR). 
• The current organisation is called the Alliance of Bioversity International and CIAT. 

1.6  Procedure of Plant Introduction

Introduction consists of six sequential steps

• Step 1 — Procurement: Any individual or institution wishing to introduce germplasm submits a request to NBPGR. Two routes: (1) Direct request from individual to a foreign institution, with material routed through NBPGR; (2) Individual submits requirements to NBPGR, which procures the material from abroad.
• Step 2 — Quarantine: All introduced plant propagules are thoroughly inspected for weed seeds, diseases, and insect pests. Contaminated materials are fumigated or treated. Materials suspected of carrying diseases may be grown in isolation for observation. The entire inspection process is quarantine; the rules governing it are quarantine rules. Post Entry Quarantine (PEQ) may be required for certain materials.
• Step 3 — Cataloguing: Each introduction receives an entry number. Information recorded includes: species name, variety name, place of origin, adaptation, and characteristics. Three prefixes are used:

• EC — Exotic Collections
• IC — Indigenous Collections
• IW — Indigenous Wild Collections

• Step 4 — Evaluation: Performance of new introductions is evaluated at different substations of NBPGR or by the relevant Central Research Institutes. Resistance to diseases and pests is evaluated under environments favouring heavy pathogen/pest attacks.
• Step 5 — Acclimatization: Many introduced varieties perform poorly initially because they are not adapted to the new environment. With successive generations grown in the new environment, performance may improve — this gradual adaptation process is acclimatization. ('the process that leads to the adaptation of a variety to a new environment.') It is brought about by a faster multiplication of those genotypes within the original population that are better adapted to the new environment — essentially natural selection.

• Success of acclimatization depends on: 

• mode of pollination (cross-pollination leads to more gene recombination, helping acclimatization); 
• range of genetic variability in the original population; 
• duration of the life cycle. Land varieties are likely to get acclimatized; pure lines are not (because pure lines have no genetic variability within them for natural selection to act upon).

• Step 6 — Multiplication and Distribution: Promising introductions or selections are increased and released as varieties after necessary trials. Most introductions are characterised for desirable traits, maintained for future use, and supplied by the bureau on request.

1.7  Objectives and Purpose of Plant Introduction

• To obtain an entirely new crop plant: Many important Indian crops are introductions — maize, potato, tomato, tobacco, groundnut, cashewnut, chillies, guava, papaya, pineapple, sweet potato (all introduced by Portuguese). More recent introductions include soybean, gobhi sarson (Brassica napus), and oil palm.
• To serve as new varieties: Some introductions are released directly as commercial varieties without modification. Examples: Mexican semi-dwarf wheats Sonora 64 and Lerma Rojo; rice varieties TN-1, IR-8, and IR-36.
• To be used in crop improvement: Introduced material is used for hybridization with local varieties. All semi-dwarf wheat varieties in India were derived from crosses with Mexican semi-dwarf wheats. All semi-dwarf rice varieties with dwarfing gene (sd1) carry it from Dee-geo-woo-gen through TN-1 or IR-8.
• To save the crop from diseases and pests: A crop may be introduced into a new area to protect it from specific diseases. Coffee was introduced in South America from Africa to protect it from coffee leaf rust. Hevea rubber was brought to Malaya from South America to protect it from a leaf disease. 
• To enrich germplasm collections: NCAC accessions to provide rust resistance sources for groundnut; Dasal rice variety as a saline resistance source.
• For scientific studies: Collections of plants have been used for studies on biosystematics, evolution, and origin of plant species. Vavilov developed the concept of centres of origin and homologous series in variation from the study of his vast germplasm collection.
• For aesthetic value: Ornamentals, shrubs, and lawn grasses are introduced for decoration and social value.

1.8  Merits and Demerits of Plant Introduction

Merits

• Provides entirely new crop plants — many major Indian crops are introductions (potato, maize, tomato, etc.)
• Provides superior varieties either directly (primary introduction) or after selection/hybridization (secondary introduction)
• Quickest and most economical method of crop improvement when introductions can be released directly as varieties
• Only feasible means of collecting germplasm and protecting variability from genetic erosion — exploration and introduction are inseparable
• Plants can be introduced into disease-free areas to protect them from specific diseases (coffee, rubber examples)
• Enriches existing germplasm collections and increases available genetic variability for breeding

Demerits

• Introduction of new weeds: Argemone mexicana (Mexican poppy), Eichhornia crassipes (water hyacinth), Parthenium hysterophorus (congress grass/carrot weed) were accidentally introduced with crop plants. All three are now major invasive weeds in India.
• Introduction of new diseases: Late blight of potato (Phytophthora infestans) was introduced from Europe; bunchy top disease of banana came from Sri Lanka.
• Introduction of new pests: Potato tuber moth (Phthorimaea operculella) came from Italy .
• Ornamentals becoming weeds: Lantana camara — introduced as an ornamental hedge plant — has become one of India's most problematic invasive species.
• Ecological imbalance: Eucalyptus was introduced for timber and pulpwood; it is now criticised for depleting soil moisture and groundwater.