Gamma Gardens for Mutation Breeding and Crop Improvement

Gamma garden or Atomic garden is a concept popularized after the Word War 2 for the peaceful use of atomic energy (atoms for peace) for the crop improvement. They are a type of induced mutation breeding where radioactive sources particularly gamma rays from cobalt -60 or Caesium-137 are used to induce desirable mutations in crop plants. 

Gamma Garden

Ø  Gamma gardens are “area subjected to gamma irradiation of crop plants”.

Ø  They are giant structures, enclosed by thick high wall to protect the plants and animals outside.

atomic garden

Satellite Map of a Gamma Garden at Institute of Radiation Breeding, Hitachiohmiya, Japan

Ø  The purpose of a gamma garden is to irradiate the whole plants during different stages of development and of varying duration.

Ø  The source of radiation used is Cobalt-60.

Ø  Rarely Caesium-137 is also used as the source of radiation.

gamma garden

a small gamma garden with central radiation source

Ø  The strength of 60Co is 200 curies.

Ø  The source of radiation is located at the centre.

Ø  The area is divided into concentric circles with varying intensity of radiation.

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Ø  Plants to be irradiated are arranged as concentric circles around the radiation source.

Ø  The intensity of radiation decrease as one move away from source of the radiation.

Ø  The radially arranged plants in gamma garden can be grouped into three sectors.

Sector – I

o   They are plants nearest to the central radiation source.

o   Plants in the sector I usually die immediately due to the high dose of radiation.

o   They are not used in further experiments.

Sector – II

o   This include plants located next to the sector I.

o   These plants develop severe tumors, malformations and other abnormalities.

o   These plants are also not used in further experiments.

Sector – III

o   They include plants located next to sector III.

o   They are the actual plants of interest in Gamma gardens.

o   They may have random mutations not severe enough to damage the crop plant.

o   The variations obtained in the sector III are used in further breeding experiments.

o   They can be used as a source of variation in hybridization or can be directly released as a variety.

layout of a gamma garden

Ø  The first gamma garden: in Long Island, New York, USA.

Ø  First gamma garden in India: Bose Research institute at Calcutta (1959).

Ø  Second gamma garden in India: Indian Agricultural Research Institute (1960).

Advantages of Gamma Garden

Ø  Gamma gardens can produce large amount of variations within a short time.

Ø  Desirable mutants can be released directly as a new variety.

Ø  Gamma gardens are good examples of the peaceful use of atomic energy for human welfare.

Disadvantages of Gamma Garden

Ø  High initial investment required.

Ø  Other cheapest mutation methods are now available.

Ø  Chances of undesirable mutations are very high.

Ø  Mutations are random; we cannot predict the effects of mutations.

Ø  Loss of many natural good qualities of crops due to recessive mutations.

Ø  Mutated characters may not be stable as they segregate in the next generation.

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@. Mutation Breeding for Crop Improvement

@. Plant Introduction

@. Objectives of Plant Breeding

@. Achievements of Plant Breedin in India


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