AUTHOR=Penzel Martin , Herppich Werner B. , Weltzien Cornelia , Tsoulias Nikos , Zude-Sasse Manuela 

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

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.669909

DOI=10.3389/fpls.2021.669909

ISSN=1664-462X

ABSTRACT=The  capacity of apple trees to produce fruit of desired diameters, i.e., the fruit bearing capacity (FBC), was investigated considering the inter-tree variability of leaf area (LA). The LA of 996 trees of a commercial apple orchard was measured with a terrestrial 2D LiDAR laser scanner in two consecutive years. The FBC was simulated by utilising the LiDAR scanned total LA of the trees, seasonal records of fruit and leaf gas exchanges, fruit growth rates, and weather data in a carbon balance model. The FBC was compared to actual fruit size measured in a sorting line on individual trees. The variance of FBC was similar in both years, whereas individual trees showed different FBC in both seasons as indicated in spatially resolved data of FBC. Considering a target mean fruit diameter of 65 mm, FBC ranged from 84 to 168 fruit per tree in 2018 and from 55 to 179 fruit per tree in 2019 depending on the total leaf area of the trees. The simulated FBC to produce the mean harvest fruit diameter of 65 mm and the actual number of harvested fruit > 65 mm per tree were in good agreement. Fruit quality, indicated by fruit’s size and soluble solids content (SSC), showed enhanced percentages of desired fruit quality according to the seasonally total absorbed photosynthetic energy (TAPE) of the tree per fruit. To achieve a target fruit diameter and reduce the variance in SSC at harvest, the FBC should be considered in crop load management practices. For this purpose, however, annual spatial monitoring of the tree-individual FBC is required.