OECT-based in-vivo monitoring for plant science and smart agriculture

Abstract

Drought stress imposes a major constraint over a crop yield and can be expected to grow in importance if the climate change predicted comes about. Another of the main impacts of climate change on agricultural production, is the dramatic increase of saline (Na+) soils available for cultivation. Improved tools are needed to facilitate crop management via the prompt detection of the onset of each stress. In this thesis work, we reported the use of an in vivo OECT (Organic Electrochemical Transistor) sensor, named Bioristor, in the context of the drought and salt stress response of plants. For the first time in our knowledge, the device was integrated within the plant’s stem, thereby allowing for the continuous monitoring of the plant physiology during the entire plant life cycle. Bioristor was able to detect changes of ion concentration in the sap under drought, showing high correlation with the stomatal resistance index of an impaired transpiration process. In this thesis, we explored the ability of Bioristor to give a specific signal key species for the Italian agriculture: tomato and kiwi, analyzing several components of the drought stress (environmental and physiological response) and emerging techniques to increase the plant tolerance (use of biostimulants and of new varieties obtained with new techniques). The importance of VPD (Vapour Pressure Deficit) was confirmed to be one of the main drivers of water uptake and to be strongly affected by drought and showed an inverse relation with Bioristor, fostering its use as a sensor in controlled condition growth chamber and greenhouses. The application of biostimulant triggered the onset of defense responses linked to ion accumulation as showed by the strong increases of the R upon biostimulant treatment under drought. To significantly impact on water use efficiency through the optimization of the water use in agriculture, a new tool has to operate in the open field allowing tomato to calculated the percentage of water savings hypothesize with the use of Bioristor and ranging between 30 and 35 %. Thus, here we implemented Bioristor in open field cultivation of tomato and kiwi vines. In both conditions Bioristor worked for the entire season, detecting rains thus leaves wettability and allowing for the early warning of the occurrence of droughts in both species. The relationships between known physiological parameters and comparison with used tools for irrigation settings are here described and discussed. Last, Bioristor was used to monitor the dynamics of giant canes plants to explore their ability to tolerate a great amount of salt in the water and exploring the mechanisms of salt transport during the time.