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ISHS Acta Horticulturae 555: II International Symposium on Edible Alliaceae


Authors:   K. Bradley, M. Rieger, G. Collins
DOI:   10.17660/ActaHortic.2001.555.22
Garlic is a very ancient crop whose cultivation dates back to ancient Asia and the Mediterranean. The ancient Egyptians are said to have given daily rations of garlic to the labourers building the pyramids to maintain their strength and to ward off epidemics. In the twelth to fourteenth centuries, garlic soup was popular to prevent winter coughs and colds. In the 1850s, Louis Pasteur documented that garlic kills bacteria, and it was used to disinfect wounds when penicillin and sulfa drugs were in short supply.

Garlic reproduces by vegetative propagation – there are no known fertile cultivars being cultivated.

Despite the absence of fertile plants, there are many hundreds of named cultivars throughout the world – and they show wide variability in morphology, such as clove colour, clove size, and clove number. There are also wide differences in their capacity to develop a flowering head, for which there are three accepted classifications:

  1. Nonbolting types. These do not form flower stalks, or do so only rarely.
  2. Incomplete bolting types. These usually produce a flower stalk, the terminal of which (the bulbils) often remains enclosed in the pseudostem.
  3. Complete bolting types. These bolt readily producing a scape which terminates in an inflorescence containing sterile flowers and topsets (bulbils).

The fact that there are such wide variations in morphology suggests that intense selection pressure has been imposed during domestication. However, some publications suggest that there were sexually reproducing ancestors which were responsible for the genetic diversity, and that this diversity has been maintained by many years of selection.

In addition to differences in DNA, there is the possibility of phenotypic variability due to infection by viruses and viroids. This is known to occur in grapevines.

Another source of phenotypic variability is the growth response of garlic in different environments, especially the effect of daylength and temperature. It is known that, in some areas, the same cultivar has different names.

In the past, garlic identification has been based on morphological differences. More recently, gene products have been analysed e.g. isozymes. Both of these techniques have limitations, including variation due to environmental effects, and the lack of a sufficient number of differences for adequate identification.

These limitations can be overcome by using DNA to detect polymorphisms.

All garlic has been imported into Australia. Prior to 1990 import and quarantine restrictions made it very difficult to import garlic. Therefore it is likely that some of the cultivars which are grown commercially have been imported illegally. Their origins are obscure, and the names may have been changed.

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