1 / 22
Télécharger la présentation

Geneflow and persistence

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Geneflow and persistence Geoff Squire Scottish Crop Research Institute

  2. Concerns Ecological • feral populations or hybrids with wild relatives interfere with the habitat Food purity • outcrossing between nearby fields • feral populations contributing to yield

  3. The system • Soil - genesis, resilience • Primary production – crops and weeds • Decomposition – bacteria, fungi, protozoa, nematodes, collembola, etc. • Element cycling • Herbivory – nematodes, insects, cattle/sheep + humans

  4. The scales • Fine soil structure – bacterial, fungal • Field patch – plant populations • Field – management unit • Farm or group of farms • Landscape

  5. Soil is a complex medium

  6. Oilseed rape • Reappeared as a common crop in 1970s • Most Brassica napus, some B. rapa • As a ‘break’ crop in cereals • Oil has a wide range of uses • Outcrossing (contact, wind, insect) • Feral descendents (pod shatter, inducible dormancy)

  7. It has joined joined the seedbank In this small plot of 200 m-2 • 10,000 original OSR crop plants • >100,000 seed shed at harvest • 100 feral plants one year later • >1000 feral seeds still in the seedbank

  8. It has good regional coverage 1 km

  9. 1. Will it disturb the habitat? • Soil structure • Habitat processes • Other organisms

  10. Other arable plants • Seedbank – 1000 to >10,000 individuals in a square metre • 10 target weeds • 30 common, 150 less common species • Non-target species highly valuable to arable food web • From glacial and more recent

  11. Brassica napus Brassica rapa Raphanus raphanistrum Sinapis arvensis Common Cruciferae

  12. Will OSR affect rest of seedbank ? Community-scale properties

  13. Will it affect transmission through food webs ?

  14. Ecological impact - conclusions Ferals and hybrids - • Negligible effect on integrity of soil • Negligible effect on main habitat processes • Mainly fill vacant space – ferals typically 100 m-2 • But might alter seedbank species abundance or species composition • And some transmission of effect to food web

  15. 2. Impurities in yield • Distance and frequency • Persistence over time • Food quality • Perception and preference

  16. Distance and time? 1 km

  17. Gene flow depends on context f d

  18. Analysis in progress (2002) 2 km Green – oilseed rape fields Black – GM oilseed rape fields

  19. Impurities in OSR decay slowly

  20. Impurity in yield - conclusions • Not preventable in oilseed rape under present arable cropping • at low frequency over several km, mediated by a range of insect vectors and wind-borne pollen • regional process depending on the configuration of fields in a locality • cross pollination between nearby fields is 1 in 1000 or less (higher to fields of partial male fertility) • In-field ferals can contribute more (i.e. 1 in a 100) to impurities • Can be limited < 0.1% not practicable < 1% uncertain and only with the most rigorous standards

  21. Conclusions Of ferals and hybrids – • Ecological effects small • Low level of impurity in harvest will be difficult to manage • First conclusion might have to be modified if field practice changes

More Related