ISHS Acta Horticulturae 290: Genetic Resources of Temperate Fruit and Nut Crops
PEARS (PYRUS) |
| Author: | R. L. Bell |
| Abstract:
Pears are a fruit which have been cultivated in Europe since as early as 1000 B. C., when Homer wrote of the garden of Alcinous (Hedrick, 1921). In the Orient, historic records infer that pear cultivation dates to as early as the Tsing and Han dynasties, nearly 2000 years ago (Shen, 1980). Paleontological evidence of pear and related genera have been found in Tertiary deposits, and one can surmise that Stone Age man may have gathered fruit from wild trees. Selection and domestication have proceeded over a period of many centuries, resulting in a fruit which is highly prized today throughout many temperate regions of the world. Pears are usually grown as a compound genetic system, consisting of a scion, or fruit-bearing portion of the tree, grafted upon a rootstock. The particular characteristics which one desires in a rootstock, and therefore the genetic vulnerabilities, are in part distinct from those of the scion cultivar. Lombard and Westwood (1987) have recently given an excellent review of pear rootstocks. Therefore, the present chapter will not deal extensively in genetic vulnerability of current rootstocks, but will deal in a general manner with present and potential genetic resources available for either purpose. This survey will concentrate on the primary and secondary gene pools, defined as germplasm within an economically important species, and cross-compatible species belonging to the genus Pyrus, respectively. The tertiary gene pool of related genera of potential use as rootstocks or rootstock traits will not be covered in detail. | |
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