ISHS Acta Horticulturae 121: VII Symposium on Apricot Culture and Decline
CRITICAL TEMPERATURES IN WINTER (AFTER REST PERIOD) AND IN SPRING (AT BLOOMING TIME) FOR FRUIT BUDS AND OPEN FLOWERS OF SOME APRICOT VARIETIES FROM DIFFERENT GROUPS |
| Authors: | I. TAMASSY, M. ZAYAN |
| Abstract:
Because apricots are among the earliest of the fruit to bloom, there are many problems in apricot production. The most important economic problem is the damages occur in spring. Layne (1967) found that data of leaf drop and data of flowering were played a role in cold injury of apricot buds. Recently, Hatch and Walker (1969) reported that the greatest cold hadiness for apricot and peach flower buds was reached December 16 and December 23, respectivelly when 50% of the buds survived - 20 F. As indicated by Sholokhov (1961) in USSR that the end of rest period coincides with meiosis in apricot flower buds. He also indicated that the earliest differentiation was in the varieties of Eastern-Asiatic group, followed by the varieties of European and Irano-Caucasian groups. The same author also found that apricot fruit buds were reached their maximum frost resistance in the period of archesperium tissue development. Mowry (1964) working on 91 peach varieties found that open flowers had a significantly greater mortality than the unopened buds, but no significant differences in mortality were found between the balloon and pink stages of bud development. It is proposed in this study, that there are two of the most sensitive periods at which many losses of flower buds and open flowers occur in apricot orchards and these losses are large enough to limit the yearly apricot production. The first sensitive period is after rest period completation. The second sensitive period is at blooming time. The aim of this study was to determine the critical temperatures at these two periods in 8 apricot varieties belonging to different groups. | |
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