Abstract
In this study, the thinner machine with yellow rod equipment was tested in relation to tree branch length and orientation in April 2019, in a narrow-canopied apricot orchard of Emilia Romagna Region, Italy. The trees were mechanically thinned with manual finishing, and comparative tests were carried out simultaneously with the ordinary hand thinning (control). Three groups of two plants were identified as replication for a total of six plants per row. Three rows were checked, considering field uniformity average. The branches were grouped into four classes according to their length: <30 cm, 30–60 cm, 60–90 cm and >90 cm. Branch inclination on the plant, radial or longitudinal with respect to the row, was evaluated. Fruit number before the thinning, after the first and the second machine intervention, after three days of the mechanical thinning and after the hand finishing was recorded. This experience showed satisfactory results in terms of thinning efficiency and reduced damage to both fruits and branches, as a function of the class length and insertion point in the main branch of the plant. Thinning efficiency was always kept above 37% of the left load after hand finishing, and on average between the treatments close to 44%. Fruit damages always remained below the economic thresholds to marketable production or to the plant.
Highlights
Apricot (Prunus armeniaca L.) is an important fruit crop grown worldwide, and is a highly appreciated fruit by consumers [1]
The effect of mechanical thinning was immediately visible in certain parts of the trees, given that the machine’s effects were diversified, depending on branch length, orientation, and position within the canopy
Regarding branch length (Figure 2), the effect of mechanical thinning was greater on the branches 30–60 cm-long (52% of fruit detected)
Summary
Apricot (Prunus armeniaca L.) is an important fruit crop grown worldwide, and is a highly appreciated fruit by consumers [1]. In apricot tree cultivation, thinning is a central cultural practice to regulate the fruit load, to improve fruit size, yield, and quality, and to decrease alternate bearing [2,3,4]. The excess fruits are manually removed around 40–60 days after full blooming (DAFB), to produce large size fruits for market [5,6]. Thinning responses depend on environmental and soil conditions, on timing, and on management practices, such as pruning. Pruning is the earlier method to adjust crop load [5]. In some species/cultivars, reproductive and vegetative performance is related to thinning severity and timing [7,8,9]
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