Continuous Monitoring of olive fruit growth by Proximal Sensor: Case study of the Daily Rain Effect

Continuous monitoring of the transversal fruit diameter was conducted using automatic extensimeters to track growth dynamics of deficit irrigated and non-irrigated olive fruit under rainfall conditions. The study examined the daily diameter fluctuation $(\triangle D,\mathrm{~mm})$, cumulative fruit growth (CFG, mm), and fruit relative growth rate ($RGR,\mathrm{~mm}\mathrm{~mm}^{-1}\mathrm{~h}^{-1}$) of two olive cultivars (Ascolana dura and Piantone di Falerone). The regulated deficit irrigation treatment of DI-20 (20% of ETc) was implemented. The evaluation of fruit growth parameters unveiled a cultivar-specific variation in response to rehydration after rainfall. To give an example, after the occurrence of rainfall, the analysis of the lower and upper bounds of RGR demonstrated that the fruit growth dynamic in the cultivar Piantone di Falerone remained unaffected by previous water stress experience, whereas the cultivar Ascolana dura with an increasing maximum amount of RGR in non-irrigated treatment showed a noticeable response. These results can be useful for the development of more precise models for olive fruit growth and any smart olive fruit management.