Volume 30 Number 1 Article 2 Pages: 7-7
Year 1976 Month 1
Title: Early and Late Flowering in Pear
Authors: T. van der Zwet and M. Faust
Citation
Abstract:
The time of bloom in fruit trees is extremely important bacause flowers if early blooming types are often killed by frost.
Nearly all fire blight resistant Pyrus species or clonal selections bloom much earlier than the susceptible cultivars of P. communis. During the spring of 1975, we observed 34 days between the earliest and latest blooming of pear clones.
The earliest bloom of pears started 23 days before 'Bartlett' with an unidentified Pyrus species from Manchuria and continued with P. calleryana and several cultivars of the P. ussuriensis(Maxim.) group/
Examination of progenies of verious crosses of P. calleryana indicated that when P. calleryana 'Bradford' was crossed with another P. calleryana selection, full bloom of the enire progeny occurred 16-21 days before 'Bartlett'. However, when P. calleryana was crossed with P. Communis cultivars ('Moonglow', 'Roi Charles de Wurtemberg', 'US 309'), bloom of the progenies varied 5-11 days before 'Bartlett'. When selections from P. calleryana x P. Communis were back crossed to P. communis cultivars, blooming date of the progenies was recorded from 0-5 days before 'Bartlett'. The latter can be considered fully within the range of P. communis bloom.
Regardless of the difference in bloom time between parents, the bloom of the progeny occurred within a 4-5 day period.
In each progeny, no seedling flowered later than the later blooming parent.
The tendency to bloom appeated toward P. communis, and two generations were sufficient to bring the bloom time of P. calleryana to the bloom tome of P. communis.
Because the time of bloom is characteristic for each pear species, this may be used to help identify a species.
The definite transmittance of the time of bloom indicates that it is a distinct physiological phenomenon.
Its further understanding may help us develop means to delay the time of bloom.
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