Blooming charge assessment in apple orchards for automatic thinning activities

Summary This work aims to develop an automatic system capable of providing objective information about the bloom charge in an apple orchard in order to manage flower-thinning activities. The article presents and discusses the use of a mobile lab (ByeLab) equipped with several optical sensors to carry out a site-specific bloom charge assessment in apple trees. The data collected by the sensors were processed by a specific algorithm implemented in MatLab®. Investigations of the flower reflectance signature indicated that the Normalized Difference Vegetation Index (NDVI) is the most suitable parameter to distinguish leaves from flowers. Pure flowers produce NDVI values slightly negative or at least very near to 0. Despite the homogeneous behavior of the NDVI flower response, OptRx™ sensors, which provide an average assessment of an area, were not able to highlight a significant correlation between the number of flowers and the NDVI values. In the future, further studies will be conducted to assess if other techniques based on image analyses can provide better and more sensitive results regarding the bloom charge assessment. Such results could then be used as a reference in automating machines for thinning operations according to a site-specific approach.

Mechanical flower thinning in peach trees

In cultivation of peaches, thinning is conventionally performed on fruits by hand, and needs to be done in a short time and with specialized labor, which increases the operational costs of this practice. Mechanical thinning can be an alternative to manual fruit thinning. Thus, the objective of this study was to evaluate the effect of mechanical flower thinning with different equipment in advanced peach orchard. The experiment was conducted in 2016 and 2017, combining advanced selections of peach trees and thinning methods. The evaluated variables were percentage of flowers thinning, thinning time, fruit number per plant, plant production, estimated yield, average fruit mass and fruit diameter class. Flower mechanic thinning alters the yield index of peach trees. Mechanical thinning on peach trees was efficient in flower thinning and reduced the practice execution time. Therefore, mechanical thinning is an alternative to the manual fruit thinning of peach trees.