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
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
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
ex:- paper bags.
8. Factors affecting isolation distance :
Pollination behavior of crop.
Type of seed production
Class of the seed
12. Importance :
You can manage isolation through several methods:
by timing of flowering, or
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
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.
(1) wind movement
(2) pollinator pressure
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
Genetically-modified crop nearby