X-ray based seed analysis and sorting

Drs. Henry Bruggink

INCOTEC

Outline

• Background – the discovery of X-rays• Visualisation of X-rays• X-rays and seed analysis• Sorting for seed quality• Present and Future

X-Rays

Discovery of X-rays

• 1895: Dr. Wilhelm Conrad Röntgen produced radiation with an experimental electrical discharge tube: X-rays

• made photographs of “invisible” structures• 1st Nobel Prize in Physics, 1901• Father of diagnostic radiology (Medicine)• Nowadays also for Non-Destructive Testing,

airport control, crystallography, etc.

Creating a visible image

X-rays: electromagnetic radiation, 0.01 to 10 nmRöntgen used a screen of barium platinocyanide: X-ray photons are converted into light fluorescenceLater: photographic plates, filmsDisadvantages:

HP Faxitron

− long exposure times− development time− not reuseable− analogue medium

From analogue to digital radiography

Nowadays, most detectors are based on a scintillator: ionizing radiation light (fluorescence)• Image Intensifier (scintillator + photo multiplier) +

digital camera• Scintillator + photodiodes:

– Flat panel detector– Line scan camera– CCD (charge coupled device) based detector

Detectors: Image Intensifier

Input screen

PhotokathodeNa-activated CsI

Aluminum layer

Output screen

Glass window

High resolution digital camera

Digital detectors

• Flat Panel Detector– Indirect: scintillator emits

light that is captured by photodiode and translated into electrical signal

– Direct: compound (e.g. Selenium) that emits electrons when hit by X-ray photon

From Varian: PaxScan Flat panel X-ray Imaging

Digital detectors

• Line scan camera– Single line scans over

object; high energy needed– TDI (Time Delay

Integration): more lines, giving high resolution and high sensitivity

• CCD camera– Scintillator coupled to CCD

chip with fiber optics

From Hamamatsu: X-ray Line Scan Camera C10400

From Hamamatsu: X-ray Camera with Fiber Optics Window

Analysis of seeds using X-ray

The first to use X-rays for seed analysis was Lundström (1903): coniferous tree seeds

Advantages are obvious:– information on structure and condition of embryo– and on presence of insects, diseases or other defects– content of fruits (e.g. multigerm)– much faster than germination test (esp. tree seeds)

X-ray contrast method: contrasting agent dead tissue

Analysis of seeds using X-ray

Many species have been investigated of all kinds: trees, vegetables, agronomic crops, …

Haff & Slaughter (2004)

Stark & Adams (1963)

Kamra (1976)

For sugar beet: routinely used tool for cleaning and upgrading

Tomato seed

Tomato seed (W-Eur): high value, high requirements: Useable Transplants (UT) = normal, uniform size

too small: not Useable

From analysis to sorting

Van der Burg et al. (1994) - X-ray images give information– embryo size and morphology – the amount of endosperm– the area of free space

X-ray analysis can predict seedling performance (% UT) and enable the selection of high-quality seed

This lead to an initiative of Dutch companies, to develop and build an X-ray sorting system for tomato seed

Research at Incotec

Categorization of tomato seeds, imaged on film, using various parameters:

– embryo size – embryo shape– endosperm– free space– tissue density– …..(1994)

The importance of priming

• Without priming, in general poor visibility of internal structures (no free space)

• Not all primings result in good visibility!

• And: priming brings potential of a seed to expression – uniform germination– relieve of dormancy Non-primed Primed

System development

• Economically feasible: minimum capacity• Started in 1996, prototype in 2007 to Production

Some aspects• Detector:

− Flat scan: more seeds in one imageImage Intensifier

• Transport system: tray with several grids• Software:

– image processing– classification

Problem: huge variation

Variation in tomato seed

• Different grey values per seed lot: optimize settings• No consistent correlation between image and seedling

quality over various lots Intake test for each seed lot:

– make images of 800 seeds– determine seedling quality of these seeds– make correlation– make prognosis: expected amount, quality of fractions– input customer– instruct software

Sophisticated analysis software, various options

Results

54

3727

0

20

40

60

80

100

Primed seed

Option 1Option 2Option 3

Perc

enta

ge

Upgrading options

UT in fractiion Q1

Output

0

20

40

60

80

100

Primed seed Q1 Q2 Q3

Use

able

Tra

nspl

ants

(%)

Tomato: effect on Useable Transplants (n=10)

Greenhouse 25 °C, 11d after sowing

Primed seed Q1 Q2 Q3UT1 74%Fraction wht 100%

89%36%

66%45%

41%19%

Limitations of X-ray sorting

• Speed: limited capacity, only for high value seeds

• Note: larger seed size means lower capacity

• Only for flat seeds: always positioned in the same plane

• Only information on morphology, not on physiology

3N WatermelonTomato

X-ray analysis and sorting: present & future

Analysis of seeds• Digital systems are well available• Possibility to enlarge images (more info per seed)• Various developments in analysis software• 3D analysis

Sorting of seeds• Incotec will only provide services, not machines• and will expand to pepper and more crops• Developments at machine builders: systems will become

available for seed companies

Thank you for your attention

Risk of damage by X-ray

For making images of seeds: low energy (“soft”) X-raysSeveral studies: no genetic or physiological effects

0%

20%

40%

60%

80%

100%

original seed Faxitron: 12.5kV,

3.4mA, 3min

Faxitron: 25kV, 3.4mA,

3min

Faxitron: 50kV, 3.4mA,

1min

Faxitron: 50kV, 3.4mA,

3min

Yxlon: 12.3kV, 3.4mA, 10s

Yxlon: 25kV, 6mA, 10s

Effect of various X-ray doses on the GH germination of primed tomato seed

Not

Abn.

UT2

UT1

Upgrading of pepper seed

For pepper: similar results as for tomato

0.0

20.0

40.0

60.0

80.0

100.0

Primed seed Q1 Q2 Q3

Use

able

Tra

nspl

ants

(%)

Pepper: effect on Useable Transplants (n=12)