ISHS Acta Horticulturae 587: International Symposium on Asian Pears, Commemorating the 100th Anniversary of Nijisseiki Pear
ASIAN PEAR GERMPLASM - FUTURE TRENDS AND CURRENT RESEARCH IN THE INDUSTRY |
| Authors: | C.-C. Nee, C.-H. Tsai, D.D. Anstine |
| Keywords: | (High, Medium, Low) chilling requirement, HCR, MCR, LCR, pear, nursemaid culture, germplasm |
| Abstract:
An estimated 72% of all known pear species are native to Asia. The United States houses 1,500 clones, 40 % of these holdings are Asian pear cultivars. Land development throughout Asia poses a serious threat to indigenous Asian pear species. Some of these are facing extinction, i.e. P. koehnei. It is an imperative that Asian countries cooperate in a germplasm protection and preservation research venture for both native species and cultivars in the current Asian pear industry. Asian pear markets are expanding worldwide, necessitating a germplasm repository centrally located in Asia. The quality of Asian pear products is determined by breeding and selection research. A newly developed horticultural practice, we have coined the “Nursemaid” Forcing Technique (NFT), allows the grafting of imported flower buds of Japanese pears, or pear buds grown at high altitudes in Taiwan, onto the stocks of a local ‘Hengshang’ pear cultivar. Fruit is harvested much earlier than noted in traditional cultures. Asian pears are the only clones successfully commercialized in a nursemaid situation. This NFT has opened new possibilities for pear cultivation in subtropical and tropical areas. Species with low to medium-chilling requirements (LCR-MCR), i.e. P. calleryana, P. koehnei and P. pashia have vegetative sinks and growth characteristics, allowing substitution of a vegetative sink for a reproductive sink (flower bud), derived from pears trees grown in temperate zones. Westwood (1978) noted in the Genus Pyrus, there were 22 member species, 16 of which originated in Asia. Pyrus pyrifolia is the major commercial species in China, Japan, Korea and Taiwan areas. P. ussuriensis, P. pashia, P. hondoensis and ‘Kansu’ pears are also grown for local markets. The remaining species are used for rootstock; especially P. betulaefolia and P. calleryana as the rootstock of P. communis in the United States to control the disease of fire blight. Mainland China is the site where most pear species have originated. Many species were not mentioned by Westwood, like P. axmeniacaefolia Yu, P. sinensis (P. bretscheideri), P. phaeocarpa, P. serrulata and P. pseudopashia. They may be hybrid cultivars of P. pyrifolia or similar species. | |
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