APPLE CULTIVAR PERFORMANCE AND RESPONSE TO A CHEMICAL DORMANCY BREAKING SPRAY UNDER “MARGINAL” WINTER-CHILLING CONDITIONS IN ZIMBABWE

Marondera, altitude 1630 m, latitude 18° 11°S has a long-term average of only 417 hours per year at less than or equal to 7.2°C and has been generally regarded as marginal for apple production.

Cultivar trials planted in 1986 have shown that, with appropriate management, the low-chilling-requirement cvs.
Anna, Maayan, Michal and Elah on MM106 rootstock are precocious and heavy-cropping.
They flower so profusely early in spring that there is obviously no need for use of dormancy breaking sprays.

Within the same trials and others planted in 1985 a wide range of other cultivars were tested for their response to 1.5% hydrogen cyanamide.
Some, e.g.
Mutsu, cropped heavily whether treated or untreated.
Others, e.g.
Starking, showed delayed foliation and low yields if untreated but cropped heavily if treated.
Others showed intermediate cropping levels when untreated.
All cvs, were induced to crop heavily by the dormancybreaking treatment, i.e. attained the level of cropping at which fruit thinning would have been desirable to increase fruit size and at which bud-break and fruit set were no longer limiting factors.

The results have important implications both for apple production at "marginal" altitudes in Zimbabwe and for cv. breeding and selection for low-chilling environments.

IV International Symposium on Growing Temperate Zone Fruits in the Tropics and in the Subtropics

M. Bepete, J.E. Jackson

https://doi.org/10.17660/ActaHortic.1995.409.13