S17 - Session O2 - Determination of tomato fruit life stages from long-term extracellular electrophysiology recordings

Authors: Thomas Caloz, Quentin Bernard, Daniel Tran, Cédric Camps, Alja van der Schuren *, Moritz Graeff, Nigel Wallbridge, Carrol Plummer, Andrzej Kurenda

Proper fruit development is an important issue in horticultural production as it determines fruit yield and depends on many factors including cultivars and climate management. For tomatoes, even under controlled conditions, variations between fruit and trusses can be considerable. Currently, the monitoring of tomato fruit development is based on regular size and color measurements. While this aligns well with commercial demands, it is difficult to apply these methods automatically to achieve real-time fruit development monitoring. To verify if plant electrophysiology can be applied for this purpose, we performed extracellular electrophysiology measurements from the peduncle of cherry tomato trusses, covering the full life span of fruits (from early fruit set until harvest). Additionally, development of the fruits was monitored by regular fruit diameter measurements, and visual and photographic documentation. Fruit development was divided into three groups based on fruit size and color: (I) fruit division stage - fruit size < 5 mm, (II) fruit expansion stage - fruit size > 5 mm, before changing color, (III) fruit ripening stage - after changing color. Electrophysiology data sets from these different fruit life stages were subjected to comparative analyses to detect periods when signal features displayed statistically significant differences. We found that normalized daytime electrical potential values can be used to efficiently differentiate fruit division stage (I) from fruit expansion stage (II), but not expansion stage (II) from ripening stage (III). Further analyses can be performed to verify whether other features of electrical signals can be useful in the differentiation of expansion (II) and ripening (III) stages. These results demonstrate that fruit electrophysiology can be applied to monitor initial tomato life stages and that further research and development of feature analyses may enable more precise fruit life stage determination. This can be used in commercial greenhouses for fruit rate development and yield management.