Isolation Distance and it's Importance in seed Production

Seed Technology.

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. Hi gher the class of seed wider the distance. (bs v/s fs). I n hybrid seed production wider the distance than that of variety(inbred/pureline).

5. 2. Temporal Isolation C rop 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 I n surro u nding 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 varietal crossing  Intra generic crossing  Inter generic cossing

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 : I f 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 : wind movement pollinator pressure

14. P epper : Location, Time of year, Changes in insect populations, and Climatic factors.

15. T echniques F or D ecreasing T he M inimum 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:  T he 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 of flowers to pollinators remains relatively constant.

17. S ituation R equiring I ncreased Isolation Distance : Larger population of plants. Larger number of varieties. High pollinator pressure. Variety characteristics (susceptible to out crossing). Genetically-modified crop nearby

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