Fruit size and yield efficiency of 'Gala' apples grown in Chile depend on winter temperatures and season length

Abstract

The influences of several management practices, as pruning, girdling, chemical and manual thinning on apple fruit size and yield efficiency, are known. Basically, yield improvement is achieved by a successful management of source-sink relationships. However, scarce information is available today about the behavior of environmental factors. A research work was conducted on 'Gala' apples at different locations in central Chile (between 34 and 38 degrees S) among the years 2012-2016, with the objective to associate the differences detected on yield performance with the growing conditions expressed as the temperature regime during the time elapsed between autumn and flowering. For that, the mean, maximum, and minimum temperatures were used to describe weather during the autumns, winters, and early springs, for to be related with yield performance. Crop load-adjusted yield efficiency ranged between 10.1 and 6.8 kg m(-2) PAR(i), and fruit weight was found to be 134.4 g and 189.5 g among zones. The results showed that the crop load-adjusted yield and fruit size depended primarily on the maximum temperature during winter, and secondly, on season length (from bloom to harvest), with colder areas yielding better performance.