Cherry fruit growth: monitoring and 'tweeting'

Today the fruit growth monitoring is a relevant topic for smart orchard management. The monitoring of fruit growth provides relevant information to the agronomists to plan operations such as green pruning (including fruit thinning), irrigation, fertilization, pest and physiological disorders control, and to estimate the best harvest time. Smart sensors could be used to setup a decision support system that, starting from fruit monitoring, supports the users to optimize growth. We started a project based on a wide set of Internet of Thing (IoT) sensors such as dendrometers, cameras, soil temperature and volumetric water content as well weather (humidity, temperature, solar radiation) that monitor the growth of cherries at the University botanical garden and experimental farm, in Gallignano, Ancona, Italy. Dendrometers are used to map the intra-day variations of fruit size while cameras are used to map the changes over time also acting as a tool for educational purposes and extension services. Collected data are shared in a social network to inform users about the growing stages. In this case plants will “tweet” their status over the different growing stages (e.g., first swell, pre- and post-bloom, fruit set, growth and veraison, up to ripening stages) sharing media content as time-lapse videos (using cameras) and fruit growing curves. The present work compares the use of dendrometers (two fruits) with the traditional manual measurement of 50 tagged fruits in the fields and 30 sampled fruits in the laboratory. The dendrometers were set to collect data every hour while the field and lab measurements were approximately carried on every 3-5 days. The dendrometers underestimated the fruit diameter enlargement but the timing of inflection points and of linear growth rate and the final fruit growth arrest have been well described according with the other type of measurements. The dendrometers were also able to show the circadian growth of the cherry fruits, evidencing in advance an eventual growth stall which leads to fruit drop. Thus, it is possible to use the dendrometers to show the critical growth phase of cherry fruits as a base for precise application of several agronomic practices.