Proper fruit development is an important issue in horticultural production as it determines, together with crop load, the fruit yield. This development depends on many factors including cultivars and crop management based on climate. For tomatoes, even under controlled conditions, variation between fruit and trusses can be considerable. Currently, the monitoring of tomato fruit development is most often based on regular size and color measurements, in some cases combined with automated analyses of these parameters. 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 measurement from the peduncle of cherry tomato trusses. Electrophysiological recordings were performed continuously from early fruit set until the moment of the 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 visual and statistical analyses to detect periods when features were different and 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 statistical analyses may enable more precise fruit life stage determination. In order to explore the potential of electrophysiology even more, future studies may be conducted to investigate a link with fruit nutritional quality. This can then be used in commercial greenhouses for fruit rate development and yield management.
