FRUIT AND SHOOT DEVELOPMENT IN APPLE AS AFFECTED BY TEMPERATURE, LIGHT, HUMIDITY AND A POSSIBLE GREENHOUSE EFFECT IN SIMULATED LATITUDES

Container grown trees of apple cvs Katja (=Katy) and Discovery were placed in climate chambers in the Biotron, Alnarp, from just after petal fall until late autumn 1991. Three climates were simulated: A. Stockholm climate (at about 60°N), B. Modified Stockholm climate with a temperature 2°C higher than normal (a possible greenhouse effect), and C. Frankfurt climate (at about 50°N). Total shoot growth was slightly higher in trees from treatment B. Fruits were harvested according to ground colour development and ease of fruit abscission. ‘Discovery’ had extremely low fruit set in all treatments, due to poor conditions during flowering. ‘Katja’ also had a rather scanty fruit set, but sufficient to allow an evaluation of fruit properties.
Vitamin C and titratable acids contents were highest in fruits from treatment A and lowest in fruits from treatment C. Soluble solids content was also lowest in fruits from treatment C. Towards the end of the growing season the health status of the trees in treatment C was poorer than in the other treatments due to presence of spider mites.
No such differences could be found between treatment A and B. Although not statistically significant, it was a tendency towards a higher number of flowers per tree the year after the climate chamber treatments on the trees from treatment B.

International Symposium on Pre- and Postharvest Physiology of Pome-fruit

G. Redalen, M. Lindhagen, I. Huntrieser

https://doi.org/10.17660/ActaHortic.1993.326.6