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Shiro TSUYUZAKI
Plant community ecology / Environmental conservation

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

(Update on May 8, 2004. Last revised on Oct. 6, 2007)

Flotation method to extract buried seeds

Procedures

Principle

Seeds are floated by a high-concentration solution. We use 50% K2CO3 solution with cnetrifugation described below. This method is improved gradually.

Flotation method with centrifugation

Soil samples 1

↓ - add 50% K2CO3 (specific gravity = 1.54)
↓ - agitation by a high-power mechanical stirrer for a few min.2
↓ - centrifugation at > 3000 g for 3-5 min

Supernatant

↓ - filtration using an aspirator 3
Seeds and organic debris are collected on 2-3 layered miracloth
↓ - inspection uder a binocular stereomicroscope

Seed samples


[Remarks]

  1. The volume of soil sample is dependent on the volume and number of centrifugation tubes. I usually use four 200-ml centrifugation tubes at a time. Do not use glass tube.
  2. The power os Mini-stir is not enough to agitate soil sample.
  3. Wash the organic debris well using distilled water to reduce seed damage by salt solution. The side-wall of centrifugation tubes should also be washed wall to remove organic depris on the wall.

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Preparation

For flotation

Portable centrifugator
Centrifugation tubes (> 200-ml is nice)
Floatation solution (see below)
Distilled water
Beakers (size is dependent on the volume of solution)
Bottle with nozzle (to wash organic debris)
Pipette
Balance (for centrifugation)
Miracloth
Tweezers

Stirrer (shaft is better)
Aspirator
Buchner funnel
Suction bottle
Rag (floorcloth), and/or Kim-towel
Rubber gloves (if your skin is sensitive)

Flotation solution

Add 770 g K2CO3 by bits to 1 l H2O in a beaker with stirring by using a mechanical stirrer

For sorting

Binocular stereomicroscope
Tweezzers
Needle
Petri dishes
Off course, notebook and writing tools

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References
  • seedbank
  • seebank estimation
  • Ishikawa-Goto, M. & Tsuyuzaki, S. 2004. Methods of estimating seed banks with reference to long-term seed burial. Journal of Plant Research 117: 245-248
  • Tsuyuzaki, S. 1990. Methods on the researches of buried seed populations - as teaching materials. Biological Materials 25: 9-20 (in Japanese)
  • Tsuyuzaki, S. 1993. Seed viability after immersion in K2CO3 solution. Seed Science and Technology 21: 479-481
  • Tsuyuzaki, S. 1994. Rapid seed extraction from soils by a flotation method. Weed Research 34: 433-436
    • Summary (revised)

    In this study a flotation method is described which enables the rapid extraction of seeds from soil. Essentially, soil is mixed with 5.5 M K2CO3. and thoroughly dispersed by mechanical stirring for 3-6 min. The dispersed soil samples were delivered to plastic tubes, then centrifuged at more than 4,000 g for about 5 min. Buried seeds and lighter organic materials floated in the supernatant and could be removed by filtration, washed and subsequently identified. This method performed reliably using soil samples artificially burdened with white clover and a range of cultivated grass species. In addition, a wide range of weed seeds which differed in their size and densities were also effectively recovered from a range of soil types loam to gravel.

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