WP2 G&H April 2002 1

Garlic life cycle and flowering physiology

Rina KamenetskyThe Volcani Center

ISRAEL

Haim D. RabinowitchThe Hebrew University

ISRAEL

WP2 G&H April 2002 2

- Flowering as the first stage in sexual reproduction of garlic

- Flowering is a complex phenomenon that depends on

developmental stage, temperature, daylength, genetic factors,

nutrients

- Extensive research has been performed on flowering physiology

of onion, while very little is known about garlic and

other Allium crops

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Inflorescence of garlic

Topsets Floral budsGarlic (Allium sativum) is a completely

sterile plant, propagated only

vegetatively

Increase of genetic variation occurs only

via random or induced mutations,

new cultivars are bred by clonal selection

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Garlic clones are classified according to their ability to bolt:

1. Complete bolting: long stalk with many flowers and topsets

2. Incomplete bolting: thin short stalk with a few large topsets

3. Nonbolting plants: producing only cloves inside incomplete

scape

(Takagi, 1990)

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-20C 20C 40C 90C 200C

Floral scape

Bulb

• Low storage temperatures promote leaf elongation after planting • Scape elongation and bulbing were significantly faster after storage

at lower temperatures

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17/90C SD - LD

17/9-20/12-23/150C SD - LD- LD

20/12-23/150C SD-LD

17/9-20/12-23/150C SD

• In bolting type, daylength plays a dominant role in promotion of scape elongation• Interactions between growth temperatures and daylength

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2001 - 2002

Experimental design

20/120C or 20/120C - 23/150CSD 1 week LD SD

SD 2 weeks LD SD

20/120C or 20/120C - 23/150C

SD 3 weeks LD SD 20/120C or 20/120C - 23/150C

SD 4 weeks LD SD 20/120C or 20/120C - 23/150C

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Control treatments:

20/120C

20/120C - 23/150C

20/120C

20/120C - 23/150C

20/120C - 23/150C

SD LD

SD LD

SD

SD

LD

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Floral initiation, differentiation and development

were examined by light and scanning electron microscopy

Flower primordia Developing topsets

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Plants exposed to SD

never bolted and

produced many axillary leaves

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20/12 - 23/150C,

LD

20/12 - 23/150C,

SD - 2 weeks LD - SD

1 cm1 cm

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TreatmentLeaf number prior to floral

initiation

Maximal scape length

Sprouted cloves

Non-sprouted cloves

SD - LD1054.310

SD 13010

LD757.410

SD - 1 w LD - SD1031.510

SD - 2 w LD - SD1354.79

SD - 3 w LD - SD1260.59

SD - 4 w LD - SD1356.09

Growth temperatures 20/12 – 23/150C

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SD - 2 or 3 weeks LD - SD

1 cm 1 cm

SD - 4 weeks LD - SD SD - LD (after 10 weeks)1 cm 1 cm

SD - 1 week LD - SD

1 cm