Variations in natural crop load in 'Golden Delicious' apple under Belgian climatological conditions

W. Verjans, S. Remy, N. Rosa, H. Schoofs, T. Deckers
The natural crop load varies highly from year to year in 'Golden Delicious' apple under Belgian climatological conditions. To study this variation in crop load, the number of fruits tree-1 year-1 was correlated with several parameters in two different orchards for the period 2007 until 2014. Only the data of the untreated trial were used to exclude the effect of hand thinning or of plant growth regulators. Pearson correlation coefficients revealed that there are very strong negative correlations between the number of fruits tree-1 and the day number of different phenological stages at flowering time. Besides the day number at which the phenological stages occur, also the length of the period between two phenological stages had a strong correlation with the number of fruits tree-1. In the case of the period between the end of flowering and the beginning of June drop the correlation was strong and positive with the number of fruits tree-1. A comparable strong correlation was obtained between the length of the period between leaf fall in the previous year and the bud break occurrence. A moderate negative correlation occurred between the number of fruits tree-1 and the yield of the previous year. Finally, the number of fruits tree-1 strongly correlated with low flower clusters situation (less than 150 tree-1), while, when the flower cluster load was high (more than 300 tree-1), no correlation was found.
Verjans, W., Remy, S., Rosa, N., Schoofs, H. and Deckers, T. (2016). Variations in natural crop load in 'Golden Delicious' apple under Belgian climatological conditions. Acta Hortic. 1138, 27-34
DOI: 10.17660/ActaHortic.2016.1138.4
https://doi.org/10.17660/ActaHortic.2016.1138.4
correlation, prediction, phenology, Decision Support System
English