Tree-adapted mechanical flower thinning prevents yield loss caused by over-thinning of trees with low flower set in apple

Abstract

yield and fruit quality in the production of apple fruit. thinning. In the years 2011, 2014-2016, commercial orchards of 'Elstar'/M26 and 'Gala'/M9 trained as set were mechanically thinned at balloon stage (BBCH 59) with the Darwin 250 device at constant vehicle speed of 8 km h -1 with varying rotational frequency ranging from 200 revolutions per minute (rpm) to 380 rpm. Rotational frequency of the thinning device was translated to average kinetic energy (E kin [J]) production target of 119 fruit and, therefore, no yield loss by over-thinning without any positive effect of 0.23 J and 0.33 J were adequate settings to reduce crop load in 'Elstar' and 0.33 J in 'Gala' without yield the avoidance of yield loss by over-thinning of trees -1 in 'Elstar' and 2.6-7.6 t ha -1 in 'Gala'. Results indicate the to the tree's yield capacity.

Evaluation of Computer Vision Systems and Applications to Estimate Trunk Cross-Sectional Area, Flower Cluster Number, Thinning Efficacy and Yield of Apple

“…It appears that both systems could be used to manage the flower thinning with precision. For example, Penzel, et al [31] considered estimates of flower intensity as essential to manage mechanical flower thinning. In addition, these systems could be used to estimate the best timing to initiate the pollen tube growth model, developed by Yoder, Peck, Combs and Byers [16], and Peck, Combs, DeLong and Yoder [17].…”

Modeling of Individual Fruit-Bearing Capacity of Trees Is Aimed at Optimizing Fruit Quality of Malus x domestica Borkh. ‘Gala’

“…The estimation of FBC of each individual tree can be applied to develop VRAs of thinning. Mechanical VRA in thinning based on the flower set of the trees avoided over-thinning of each individual tree with a low flower set, which could increase the fruit yield by 1.4–7.6 t ha −1 (Penzel et al, 2021 ). Knowledge on the actual FBC of each individual tree may prevent overestimation and underestimation of thinning intensity and yield as confirmed in two commercial apple orchards earlier.…”

“…In fruit production, the number of apples per tree is negatively correlated to the mean fruit fresh mass (FM), coloration (Palmer et al, 1997), soluble solids content (SSC) (Link, 2000;Serra et al, 2016), and flower set in the following season (Handschack and Schmidt, 1991). Each individual apple tree may initiate up to 2,000 flowers, which significantly exceeds the commercially desired number of fruit at harvest (Penzel et al, 2021). Although a high percentage of flowers and later fruitlets will be naturally shed in flower or fruit abscission, often too many fruit remain on the tree.…”

“…Indeed, vegetative and reproductive growths vary spatially in orchards. Variability in the trunk cross-sectional area (Manfrini et al, 2020 ), number of flower clusters (Vanbrabant et al, 2020 ; Penzel et al, 2021 ), yield, mean FM, and the fruit maturity stage of each individual tree (Manfrini et al, 2020 ) within the same orchard was described. Consequently, both the individual LA (Sanz et al, 2018 ) and the LA index (Poblete-Echeverría et al, 2015 ) and the associated FBC of each individual tree may vary spatially.…”

Annual shoot growth on apple trees with variable canopy leaf area and crop load in response to LiDAR scanned leaf area to fruit ratio

“…Spatial variability in the trunk cross-sectional area, yield (Manfrini et al, 2020), fruit quality, canopy LA (Tsoulias et al, 2022), and the flower set (Penzel et al, 2021c) of individual fruit trees in commercial orchards have been described previously. Among the endogenous growth factors, it may be shown that both the small and large scale spatial variability of soil properties (Umali et al, 2012;Käthner et al, 2017) and terrain features can contribute to the inter-tree variability in yield and fruit quality.…”