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Isolation distance IN SEED PRODUCTION

  1. 1. WELCOME
  2. 2. Isolation distance and its importance
  3. 3. 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
  4. 4. Types of isolation Types of Isolation: • 1. Spatial Isolation • 2. Temporal Isolation • 3. Physical barrier
  5. 5. 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. •more the extent of out crossing wider the distance. • 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).
  6. 6. 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.
  7. 7. 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 .
  8. 8. 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.
  9. 9. Factors affecting isolation distance.  Pollination behavior of crop.  Pollinating agent  Pollen trails  Wide pollinator  Designated diseases  Type of seed production  Class of the seed
  10. 10. Pollination behavior of crop. plants that primarily self-pollinate require less isolation distance, while plants that primarily cross- pollinate require greater distances.
  11. 11. Pollination agents 1. pollination. ABIOTIC POLLINATION  Wind Pollination:  Water and Rain Pollination: BIOTIC POLLINATION (INSECT POLLINATION)  Domesticated bees (honeybees):  Bumblebees  Butterflies:  Moths:  Flies  Wasps
  12. 12. Pollen trails  Pollen viability  Pollen production capacity  Pollen mate and  Time of anthesis
  13. 13. Wide pollinator  Inter varietal crossing  Intra generic crossing  Inter generic cossing
  14. 14. Designated diseases Crop Designated disease Causal organism Wheat Loose smut Ustilago tritici Sorghum Grain smut or Kernel smut Sphacelotheca sorghii Mustard Alternaria blight Alternaria sp Pearl millet Grain smut Green ear Ergot Tolyposporium penicillariae Sclerospora graminicola Claviceps microcephala Sesame Leaf spot Alternaria sp Brinjal Little leaf Datura virus 2 Chilies Anthracnose leaf blight Leaf blight Gloesporium piperatum Alternaria solani Cucurbits Mosaic Cucumis virus Cowpea Anthracnose Colletotricum sp Bhendi Yellow vein mosaic Hibiscus virus 1 Potato Brown rot Root knot nematode Pseudomonas solanacearum Meloidogyne incognita Tomato Early blight Leaf spot Alternaria solani Xanthomonas vesicatoria It refers to the diseases specified for the certification of seeds and for which certification standards must be met with.
  15. 15. Class of the seed higher the class of seed wider the distance. that is breeder seed production requires relatively large isolation distance compared to foundation seed production i.e breeder seed> foundation seed> certified seed> elite seed production.
  16. 16. Type of seed production In hybrid seed production wider the distance than that of varietal improvement (inbred pureline).
  17. 17. Importance  Isolation prevents unwanted cross-pollination  It is the primary practice required to keep varieties true to type.  Isolation begins with an understanding of the distance required to limit or eliminate chances of cross-pollination between two varieties of the same species.  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.
  18. 18. Factors affecting isolation distance for different crops. Okra  By the size of the growing area. In large intensively cultivated fields, the amount of cross pollination is smaller than it would be in small fields because the ratio of pollinators to plants is smaller in large plots than in small plots.  In addition, 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.
  19. 19. TOMATO (1) wind movement (2) Variety characteristics such as style length (3) environmental variables affecting style length (4) pollinator pressure (5) isolation distance (6) biodiversity - presence of other pollen-producing plants in the area of the seed crop.
  20. 20. PEPPER such as  Location,  Time of year,  Changes in insect populations, and  Climatic factors.  Several seed saving guides recommend isolation distances ranging from “several feet” to “50 feet”,
  21. 21. TECHNIQUES FOR DECREASING THE MINIMUM ISOLATION DISTANCE Plant in blocks rather than rows:  Planting crops in blocks rather than rows decreases the exposure of crops to foreign pollen.  A block planting has a much smaller periphery than a row planting.
  22. 22. Collect seed from center of block plantings:  This technique is an extension of the previous technique, and takes edge effects into account.  There usually will be a larger percentage of pollinators at the edges of a block than in the center of the block.  Therefore, the plants in the center of the block are more likely to produce pure seed than those at the edges.
  23. 23. Collect seed from fruits produced during peak flowering:  At low planting densities, the ratio of flowers to pollinators remains relatively constant.  As the number of flowers increases toward maximum blooming, a point may be reached in which the ratio of flowers to pollinators increases.
  24. 24. Use barrier crops: Barrier crops serve several functions:  1. They provide a physical barrier for pollinators, disrupting the line of flight and the line of sight.  2. They distract pollinators by providing alternative pollen and nectar sources.
  25. 25. Isolate in time (staggered blooming times): An early variety of crop plant can be planted early in the season, followed three weeks later by a planting a late variety crop.
  26. 26. SITUATIONS REQUIRING INCREASED ISOLATION DISTANCE  Larger population of plants.  Larger number of varieties.  High pollinator pressure.  Variety characteristics (susceptible to out crossing).  Genetically-modified crop nearby
  27. 27. SUMMARY OF ISOLATION DISTANCE FACTORS AND ADJUSTMENTS FACTORS HAVING AN EFFECT ON ISOLATION DISTANCE INCREASE OR DECREASE DISTANCE Plants planted in blocks rather than rows Decrease permissible Seed collection from center of blocks Decrease permissible Seed collected only from peak production Decrease permissible Use of barrier crops Decrease permissible Use of alternate pollen and nectar sources Decrease permissible Time isolation (staggered blooming times) Decrease permissible Large seed crop population size of each variety Increase suggested Larger number of varieties grown for seed Increase suggested High pollinator pressure due to apiculture Increase required High pollinator pressure due to biodiversity Increase required Organic agricultural practices instead of conventional Increase required Variety characteristics which favor outcrossing Increase required Genetically modified crop grown nearby Increase required
  28. 28. Crop Distance for Distance for (m) Foundation seed (m) Certified seed (m) Self pollinated crops Rice, Wheat, Ragi, 3 3 Groundnut, Greengram, Cowpea, Tomato Cross Pollinated Crops Maize, Mustered, 400 200 Pearlmillet, 1000 25 Lucerne, 400 100 Suhemp 200 100 Castor 300 150 Sunflower 1000 500 Carrot 1000 800 Onion 1000 400 Cucumber 800 400 Often Cross Pollinated Crop Pigeonpea 100 50 Cotton 50 30 Sorghum 200 100 Chilli, Brinjal 200 100 Isolation distance for different crops.
  29. 29. Refrences   http:// IsolationDistancesVer_1pt5   content/uploads/2012/05/IsolationDistancesVer_1pt5.pdf
  30. 30. Thank you….. Presented by Mahammed faizan MH2TAG0165 Jr.M.Sc ( hort) in GPB College of horticulture mudigere.