ESTIMATION OF FLOWERING DATE AND TEMPERATURE CHARACTERISTICS OF FRUIT TREES BY DTS METHOD

A theory and a method were developed for obtaining temperature characteristics for the flowering period of deciduous and citrus fruit trees from the number of days transformed to standard temperature (DTS) based on the Arrhenius law. Three temperature characteristics, i.e. (1) starting date of calculation (ST day), (2) temperature sensitivity (Ea) or temperature coefficient of growth rate (K) and (3) DTS from ST day to flowering time, were determined in a total of 186 cultivars from 11 species on the Main Island of Japan (Honshu) based on the daily mean air temperature and flowering date recorded over a period of at least 10 years. These temperature characteristics differed among cultivated species and may enable to estimate the flowering date. Discipline: Horticulture Additional key words: temperature sensitivity, Arrhenius law, deciduous and citrus fruit trees