1. Isolation distance and its importance

2. INTRODUCTION
Isolation distance:
 Isolation distance is the minimum separation required
between two or more varieties of the same species for the
purpose of keeping seed pure

3. Types of isolation :
 Spatial Isolation
 Temporal Isolation
 Physical barrier

4. 1. Spatial Isolation :
 The spatial separation required between a seed field and
other sources of genetic and mechanical contamination,
especially between varieties of cross pollination.
 Higher the class of seed wider the distance. (bs v/s fs).
 In hybrid seed production wider the distance than that of
variety(inbred/pureline).

5. 2. Temporal Isolation
 Crop of seed production should be sown early or late by a
margin of 15-20 days than neighboring fields of same or
other variety to prevent entry of foreign pollens in the field of
seed production.

6. 3. Physical barrier
 In surrounding of crop of seed
production particularly on bunds
crop of well plant height and
densely planted should be grown to
prevent entry of foreign pollens in
the field of seed production .

7. 4. Physical isolation
 It can be practiced by covering the floral part or whole
plant we can avoid the physical contaminants into seed
field
 ex:- paper bags.

8. Factors affecting isolation distance :
 Pollination behavior of crop.
 Pollinating agent
 Pollen trails
 Wide pollinator
 Designated diseases
 Type of seed production
 Class of the seed

9. Pollination agents :
1. pollination.
ABIOTIC POLLINATION
Wind Pollination:
Water and Rain Pollination:
BIOTIC POLLINATION (INSECT POLLINATION)
Domesticated bees (honeybees):
Bumblebees
Butterflies:
Moths:
Flies
Wasps

10. Pollen trails :
Pollen viability
Pollen production capacity
Pollen mate and
Time of anthesis

11. Wide pollinator :
Inter varietalcrossing
Intra genericcrossing
Inter genericcossing

12. Importance :
 You can manage isolation through several methods:
 by distance,
 by timing of flowering, or
 by containment.
 Isolation by distance is the most reliable method, which involves providing
enough distance between a variety and any sources of contaminating pollen
to ensure that the variety remains true to type.
 Isolation prevents unwanted cross-pollination
 It is the primary practice required to keep varieties true to type.

13. Factors affecting isolation distance for
different crops
Okra :
 If the fields have been sprayed with agro- chemicals, the
pollinator pressure will be even less, and the amount of cross-
pollination will be correspondingly lower.
Tomato :
(1) wind movement
(2) pollinator pressure

14. Pepper:
 Location,
 Time of year,
 Changes in insect populations, and
 Climatic factors.

15. TechniquesFor DecreasingTheMinimum
Isolation Distance :
Plant in blocks rather than rows:
Planting crops in blocks rather than rows decreases the exposure
of crops to foreign pollen.

16. Collect seed from center of block plantings:
The plants in the center of the block are more likely to
produce pure seed than those at the edges.
Collect seed from fruits produced during peak flowering:
At low planting densities, the ratio offlowers to
pollinators remains relatively constant.

17. Situation Requiring IncreasedIsolation Distance:
 Larger population of plants.
 Larger number of varieties.
 High pollinator pressure.
 Variety characteristics (susceptible to out
crossing).
 Genetically-modified crop nearby

18. Thank You