Plant introduction and acclimatization

Plant introduction

Plant introduction is process of taking a plant or its variety to an entirely new locality. In other words, a genotype or group of genotypes is transferred from their growing locality to new locality, where it was not grown previously.
This is the easiest and most common method of crop improvement.
Plant introduction is of two types.

1. Primary introduction, and
2. Secondary introduction

Primary introduction

When agroclimatic conditions of both the localities (original and new place) are almost same, the introduced plant is released for general cultivation without any alteration of genotype. This is primary introduction.
Examples:

• Semi-dwarf varieties of wheat ‘Sonora-64’ and ‘Lerma rojo’ were introduced in India from CIMMYT, Mexico during 1960s.
• Dwarf rice varieties ‘Taichung Native 1’ from Taiwan and ‘IR-8' from Philippines were introduced in India during 1960s.
• Introduction of 'oil palm' in India from Malaysia.

Secondary introduction

In secondary introduced varieties are subjected to change in genotype by selection or through hybridization with local varieties in order to improve the desired traits before releasing for general cultivation.
Secondary introduction is more common than primary introduction
Examples:

• Semi-dwarf wheat varieties ‘Kalyan sona’ and ‘Sonalika introduced from CIMMYT, Mexico in 1963.
• 'EC 39821' variety of soybean introduced from Taiwan was subjected to selection and variety 'Co 1' was developed.

Objectives of introduction

• To introduce high yielding varieties for use as food, fiber, wood or medicinal purposes.
• To enrich the germplasm collection for conservation and maintenance of lines, clones, mutants, cultivars, etc.
• To get new source of resistance against various stress in crops.
• To introduce plant with aesthetic values used for beautification.

Merits

• It provides new plants to a place.
• New varieties can be used directly or after improving with local germplasm.
• This method is easiest and quick.
• Introduction to a new place saves the plant from diseases.

Demerits

• Along with the crops plants certain weed have be introduced in India unknowingly, e.g., Argemone, Eichhornia, Lantana, Parthenium.
• Late blight of potato was introduced from Europe and Bunchy top of banana from Sri Lanka.
• Introduction of Eucalyptus causes ecological imbalance.

Acclimatization

Acclimatization is the process, whereby introduced plants, line or population are subjected to adapt in the existing environmental condition. This step is followed after the introduction. In this process the plant or population are allowed to adjust in the changed agroclimatic conditions for a number of generation. This process is a natural selection, whereby better adapted plants multiply faster and are selected by the nature from the introduced plant population.

Determining factors in acclimatization

Following factors determine the extent of acclimatization.

1. Genetic variability

Genetic variability is the prerequisite for acclimatization. Genetic variability provides source of natural selection.

2. Mode of pollination

Cross pollination promotes the genetic variability among the population. More the genetic variability, greater will be the extent of acclimatization.

3. Duration of life cycle

Crops with short life span have more generation in less time duration. This provides more cycle for natural selection in less time. Hence, annual crops are acclimatized in less time.

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First published on 13-04-2021
Last updated on 06-05-2021