THE INFLUENCE OF AUTUMN TEMPERATURE ON FLOWERING TIME AND CROPPING OFPYRUS-COMMUNIS CV CONFERENCE

The influence of autumn temperatures on flowering and cropping date wa s examined for Pyrus communis cv. Conference, Warming potted trees in both October and November delayed bud development and the date of blos soming, relative to unheated control and field-grown trees. The later the warming treatment was applied in the autumn, the more the flowerin g date was delayed. The delay in flowering date is suggested to be due to an increase in bud dormancy in response to a reduction in winter c hilling. Mean fruit yields and fruit number per tree were greater in t rees warmed during October compared with unheated control trees, but d eclined with heating in November. Some evidence is presented which sug gests that flower number per cluster may decline with warming. Both th e initial and final set increased with warming. Fruit set was also lik ely to have been influenced by treatment differences in fruit number p er tree. The results ofthis work are discussed in relation to attempts to provide a physiological understanding of recently reported effects of temperature on the year-to-year variation in cv. Conference croppi ng.