Study of the variability of Red Delicious apple yields in the fields of the Río Negro Upper Valley, Argentina

  The yields of apple crops (Malus domestica) depend on factors involving the crop itself, the environment and the technology applied. A combination of these factors results in variations in fruit quantity and quality both among and within orchards as well as between different years in the same growing region. The objective of this work was to study the nature of yield variability of the Red Delicious apple orchards in the Rio Negro Upper Valley, Argentina. During 4 growing seasons, the amount of fruit produced per hectare in 89 orchards was evaluated in experimental units selected according to their age and training system. The main source of variation was an effect of orchard, this was followed in importance by year, age and training system. A Gamma distribution was fitted to the data and no significant difference was observed for the scale and shape parameters of the analyzed factors. The magnitude of the observed variability between orchards of the same class suggests that the analysis of other factors (technological, social, etc.), which were not considered in this study, may add further information to characterize and explain variability in crop productivity.